This module describes the typesetting controls of CSS;
that is, the features of CSS that control the translation of
source text to formatted, line-wrapped text.
Various CSS properties provide control over
[[#transforming|case transformation]],
[[#white-space-processing|white space collapsing]],
[[#white-space-property|text wrapping]],
[[#line-breaking|line breaking rules]]
and [[#hyphenation|hyphenation]],
[[#justification|alignment and justification]],
[[#spacing|spacing]],
and [[#edge-effects|indentation]].
See [[#changes-L3]] for additions since [[CSS-TEXT-3|Level 3]].
Note: Font selection is covered in the CSS Fonts Module.
[[CSS-FONTS-3]]
Features for decorating text,
such as [[css-text-decor-3#line-decoration|underlines]],
[[css-text-decor-3#emphasis-marks|emphasis marks]],
and [[css-text-decor-3#text-shadow-property|shadows]],
(previously part of this module)
are covered in the
CSS Text Decoration Module.
[[CSS-TEXT-DECOR-3]]
[[css-writing-modes-4#text-direction|Bidirectional]] and
[[css-writing-modes-4#vertical-intro|vertical]] text
are addressed in the
CSS Writing Modes Module.
[[CSS-WRITING-MODES-4]].
Further information about the typesetting requirements
of various languages and writing systems around the world
can be found in the Internationalization Working Group’s
Language Enablement Index.
[[TYPOGRAPHY]]
removing-collapsible-crash.html
removing-collapsible-spaces-before-float-crash.html
crashtests/line-break-float-crash.html
crashtests/trailing-space-with-cr-crash.html
ellisize-rtl-text-crash.html
altering-dom-crash.html
whitespace-followed-by-cham-symbol-crash.html
white-space/append-whitespace-only-node-crash-001.html
crashtests/rendering-rtl-bidi-override-crash.html
crashtests/rendering-table-caption-with-list-item-and-svg-crash.html
crashtests/rendering-table-caption-with-negative-margins-crash.html
crashtests/white-space-pre-wrap-chash.html
crashtests/word-spacing-large-value.html
crashtests/eol-spaces-bidi-min-content-crash.html
crashtests/overflow-wrap-anywhere-crash.html
crashtests/text-indent-each-line-crash.html
overflow-wrap/crashtests/overflow-wrap-leading-floats-crash.html
text-autospace/crashtests/text-autospace-shape-cache-crash.html
text-indent/text-indent-ruby-crash.html
hyphens/hyphens-auto-wordbreak-breakall-crash.html
This specification follows the [[CSS2/about#property-defs|CSS property definition conventions]] from [[!CSS2]]
using the [[css-values-3#value-defs|value definition syntax]] from [[!CSS-VALUES-3]].
Value types not defined in this specification are defined in CSS Values & Units [[!CSS-VALUES-3]].
Combination with other CSS modules may expand the definitions of these value types.
In addition to the property-specific values listed in their definitions,
all properties defined in this specification
also accept the [=CSS-wide keywords=] as their property value.
For readability they have not been repeated explicitly.
Languages and Typesetting
Authors should accurately language-tag their content
for the best typographic behavior.
Many typographic effects vary by linguistic context.
Language and writing system conventions can affect
line breaking, hyphenation, justification, glyph selection,
and many other typographic effects.
In CSS, language-specific typographic tailorings
are only applied when the [=content language=] is known (declared).
Therefore,
higher quality typography requires authors to communicate to the UA
the correct linguistic context of the text in the document.
The content language of an element is the (human) language
the element is declared to be in, according to the rules of the
[=document language=].
Note that it is possible for the [=content language=] of an element
to be unknown--
e.g. untagged content,
or content in a [=document language=] that does not have a language-tagging facility,
is considered to have an unknown [=content language=].
Note: Authors can declare the [=content language=]
using the global lang attribute in HTML
or the universal xml:lang attribute in XML.
See the rules for determining the content language of an HTML element
in HTML,
and the [[XML#sec-lang-tag|rules for determining the content language of an XML element]] in XML 1.0.
[[HTML]]
[[XML10]]
The [=content language=] an element is declared to be in
also identifies the specific written form of that language used in that element,
known as the content writing system.
Depending on the [=document language=]’s facilities for identifying the [=content language=],
this information can be explicit or implied.
See the normative [[#script-tagging]].
Note: Some languages have more than one writing system tradition;
in other cases a language can be transliterated into a foreign writing system.
Authors should [[#script-tagging|subtag]] such cases
so that the UA can adapt appropriately.
For example, Korean (ko) can be written in
Hangul (-Hang),
Hanja (-Hani),
or a combination (-Kore).
Historical documents written solely in Hanja
do not use word spaces and
are formatted more like modern Chinese than modern Korean.
In other words, for typographic purposes ko-Hani
behaves more like zh-Hant
than ko (ko-Kore).
As another example Japanese (ja) is typically written
in a combination (-Japn) of Hiragana (-Hira),
Katakana (-Kana), and Kanji (-Hani).
However, it can also be “romanized” into Latin (-Latn)
for special purposes like language-learning textbooks,
in which case it should be formatted more like English than Japanese.
As a third example contemporary Mongolian is written in two scripts:
Cyrillic (-Cyrl, officially used in Mongolia)
and Mongolian (-Mong, more common in Inner Mongolia, part of China).
These have very different formatting requirements,
with Cyrillic behaving similar to Latin and Greek,
and Mongolian deriving from both Arabic and Chinese writing conventions.
Characters and Letters
The basic unit of typesetting is the character.
However, because writing systems are not always as simple as the basic English alphabet,
what a [=character=] actually is depends on the context in which the term is used.
For example, in Hangul (the Korean writing system),
each square representation of a syllable
(e.g. 한=Han)
can be considered a character.
However, the square symbol is really composed of multiple letters each representing a phoneme
(e.g. ㅎ=h,
ㅏ=a,
ㄴ=n)
and these also could each be considered a character.
A basic unit of computer text encoding, for any given encoding,
is also called a [=character=],
and depending on the encoding,
a single encoding [=character=] might correspond
to the entire pre-composed syllabic [=character=] (e.g. 한),
to the individual phonemic [=character=] (e.g. ㅎ),
or to smaller units such as
a base letterform (e.g. ㅇ)
and any combining marks that vary it (e.g. extra strokes that represent aspiration).
In turn, a single encoding [=character=] can be represented in the data stream as one or more bytes;
and in programming environments one byte is sometimes also called a [=character=].
Therefore the term [=character=] is fairly ambiguous where technical precision is required.
For text layout, we will refer to the typographic character unit
as the basic unit of text.
Even within the realm of text layout,
the relevant [=character=] unit depends on the operation.
For example, line-breaking and letter-spacing will segment
a sequence of Thai characters that include U+0E33 ำ THAI CHARACTER SARA AM differently;
or the behavior of a conjunct consonant in a script such as Devanagari
may depend on the font in use.
So the [=typographic character=] represents a unit of the writing system--
such as a Latin alphabetic letter (including its diacritics),
Hangul syllable,
Chinese ideographic character,
Myanmar syllable cluster--
that is indivisible with respect to a particular typographic operation
(line-breaking, first-letter effects, tracking, justification, vertical arrangement, etc.).
word-break/word-break-break-all-007.html
word-break/word-break-break-all-008.html
Unicode Standard Annex #29: Text Segmentation
defines a unit called the grapheme cluster
which approximates the [=typographic character=].
[[!UAX29]]
A UA must use the extended grapheme cluster
(not legacy grapheme cluster), as defined in UAX29,
as the basis for its [=typographic character unit=].
However, the UA should tailor the definitions
as required by typographic tradition
since the default rules are not always appropriate or ideal--
and is expected to tailor them differently
depending on the operation as needed.
line-breaking/line-breaking-013.html
line-breaking/line-breaking-014.html
Note: The rules for such tailorings are out of scope for CSS.
The following are some examples of [=typographic character unit=] tailorings
required by standard typesetting practice:
In some scripts such as Myanmar or Devanagari,
the [=typographic character unit=] for both justification and line-breaking
is an entire syllable,
which can include more than one Unicode [=grapheme cluster=].
[[!UAX29]]
In other scripts such as Thai or Lao,
even though for line-breaking the [=typographic character=]
matches Unicode’s default [=grapheme clusters=],
for letter-spacing the relevant unit
is less than a Unicode [=grapheme cluster=],
and may require decomposition or other substitutions
before spacing can be inserted.
[[!UAX29]]
For instance,
to properly letter-space the Thai word คำ (U+0E04 + U+0E33),
the U+0E33 needs to be decomposed into U+0E4D + U+0E32,
and then the extra letter-space inserted before the U+0E32: คํ า.
A slightly more complex example is น้ำ (U+0E19 + U+0E49 + U+0E33).
In this case, normal Thai shaping will first decompose the U+0E33 into U+0E4D + U+0E32
and then swap the U+0E4D with the U+0E49, giving U+0E19 + U+0E4D + U+0E49 + U+0E32.
As before the extra letter-space is then inserted before the U+0E32: นํ้ า.
Vertical typesetting can also require tailoring.
For example, when typesetting ''text-orientation/upright'' text,
Tibetan tsek and shad marks are kept with the preceding grapheme cluster,
rather than treated as an independent [=typographic character unit=].
[[!CSS-WRITING-MODES-4]]
A typographic letter unit
(or letter for the purpose of this specification)
is a [=typographic character unit=] belonging to one of the Letter or Number
[=general categories=].
See [[#character-properties]]
for how to determine the Unicode properties of a [=typographic character unit=].
The rendering characteristics of a [=typographic character unit=] divided
by an element boundary is undefined.
Ideally each component should be rendered
according to the formatting requirements of its respective element’s properties
while maintaining correct shaping and positioning
of the [=typographic character unit=] as a whole.
However, depending on the nature of the formatting differences between its parts
and the capabilities of the font technology in use,
this is not always possible.
Therefore such a [=typographic character unit=]
may be rendered as belonging to either side of the boundary,
or as some approximation of belonging to both.
Authors are forewarned that dividing [=grapheme clusters=]
or ligatures
by element boundaries may give inconsistent or undesired results.
Text Processing
CSS is built on Unicode.
[[UNICODE]]
UAs that support Unicode must adhere to all normative requirements
of the Unicode Core Standard,
except where explicitly overridden by CSS.
UAs implemented on the basis of a non-Unicode text encoding model are still
expected to fulfill the same text handling requirements
by assuming an appropriate mapping and analogous behavior.
text-encoding/shaping-join-001.html
text-encoding/shaping-join-002.html
text-encoding/shaping-join-003.html
text-encoding/shaping-no-join-001.html
text-encoding/shaping-no-join-002.html
text-encoding/shaping-no-join-003.html
text-encoding/shaping-tatweel-001.html
text-encoding/shaping-tatweel-002.html
text-encoding/shaping-tatweel-003.html
shaping/shaping-arabic-diacritics-001.html
shaping/shaping-arabic-diacritics-002.html
white-space/full-width-leading-spaces-005.html
white-space/object-replacement-1.html
white-space/object-replacement-2.html
white-space/white-space-vs-joiners-001.html
white-space/white-space-vs-joiners-002.html
For the purpose of determining adjacency for text processing
(such as white space processing, text transformation, line-breaking, etc.),
and thus in general within this specification,
intervening [=inline box=] boundaries and [=out-of-flow=] elements
must be ignored.
With respect to text shaping, however, see [[#boundary-shaping]].
line-breaking/line-breaking-002.html
line-breaking/line-breaking-003.html
line-breaking/line-breaking-004.html
line-breaking/line-breaking-005.html
line-breaking/line-breaking-006.html
line-breaking/line-breaking-007.html
line-breaking/line-breaking-008.html
word-break/word-break-min-content-002.html
word-break/word-break-min-content-003.html
word-break/word-break-min-content-004.html
word-break/word-break-min-content-005.html
overflow-wrap/overflow-wrap-anywhere-010.html
white-space-processing-048.xht
white-space-processing-049.xht
inheritance.html
parsing/text-transform-valid.html
parsing/text-transform-invalid.html
parsing/text-transform-computed.html
text-transform/text-transform-multiple-001.html
c545-txttrans-000.xht
text-transform-005.xht
text-transform-applies-to-001.xht
text-transform-applies-to-002.xht
text-transform-applies-to-003.xht
text-transform-applies-to-005.xht
text-transform-applies-to-006.xht
text-transform-applies-to-007.xht
text-transform-applies-to-008.xht
text-transform-applies-to-009.xht
text-transform-applies-to-010.xht
text-transform-applies-to-011.xht
text-transform-applies-to-012.xht
text-transform-applies-to-013.xht
text-transform-applies-to-014.xht
text-transform-applies-to-015.xht
This property transforms text for styling purposes.
It has no effect on the underlying content,
and must not affect the content of a plain text copy & paste operation.
text-transform/text-transform-upperlower-105.html
Advisement: Authors must not rely on 'text-transform' for semantic purposes;
rather the correct casing and semantics should be encoded
in the source document text and markup.
text-transform/text-transform-copy-paste-001-manual.html
Values have the following meanings:
none
No effects.
text-transform/text-transform-none-001.xht
text-transform-004.xht
capitalize
Puts the first [=typographic letter unit=] of each word, if lowercase, in titlecase;
other characters are unaffected.
text-transform/text-transform-capitalize-001.html
text-transform/text-transform-capitalize-003.html
text-transform/text-transform-capitalize-005.html
text-transform/text-transform-capitalize-007.html
text-transform/text-transform-capitalize-009.html
text-transform/text-transform-capitalize-010.html
text-transform/text-transform-capitalize-011.html
text-transform/text-transform-capitalize-014.html
text-transform/text-transform-capitalize-016.html
text-transform/text-transform-capitalize-018.html
text-transform/text-transform-capitalize-020.html
text-transform/text-transform-capitalize-022.html
text-transform/text-transform-capitalize-024.html
text-transform/text-transform-capitalize-026.html
text-transform/text-transform-capitalize-028.html
text-transform/text-transform-capitalize-030.html
text-transform/text-transform-capitalize-031.html
text-transform/text-transform-capitalize-032.xht
text-transform/text-transform-capitalize-034.html
text-transform/text-transform-capitalize-035.html
text-transform-001.xht
text-transform-cap-001.xht
text-transform-cap-002.xht
text-transform-cap-003.xht
Puts all [=typographic character units=] in [=full-width=] form.
If a character does not have a corresponding [=full-width=] form,
it is left as is.
This value is typically used to typeset Latin letters and digits
as if they were ideographic characters.
text-transform/text-transform-fullwidth-001.xht
text-transform/text-transform-fullwidth-002.xht
text-transform/text-transform-fullwidth-004.xht
text-transform/text-transform-fullwidth-005.xht
full-size-kana
Converts all [=small Kana=] characters to the equivalent [=full-size Kana=].
This value is typically used for ruby annotation text,
where authors may want all small Kana to be drawn as large Kana
to compensate for legibility issues at the small font sizes typically used in ruby.
text-transform/text-transform-full-size-kana-001.html
text-transform/text-transform-full-size-kana-002.html
text-transform/text-transform-full-size-kana-003.html
text-transform/text-transform-full-size-kana-004.html
text-transform/text-transform-full-size-kana-005.html
text-transform/text-transform-full-size-kana-006.html
text-transform/text-transform-full-size-kana-007.html
text-transform/text-transform-full-size-kana-008.html
math-auto
See [[mathml-core#math-auto-transform]].
text-transform/math/text-transform-math-auto-001.html
text-transform/math/text-transform-math-auto-002.html
text-transform/math/text-transform-math-auto-003.html
The following example converts the ASCII characters
used in abbreviations in Japanese text to their full-width variants
so that they lay out and line break like ideographs:
abbr:lang(ja) { text-transform: full-width; }
Note: The purpose of 'text-transform' is
to allow for presentational casing transformations
without affecting the semantics of the document.
Note in particular that 'text-transform' casing operations are lossy,
and can distort the meaning of a text.
While accessibility interfaces may wish to convey
the apparent casing of the rendered text to the user,
the transformed text cannot be relied on to accurately represent
the underlying meaning of the document.
In this example,
the first line of text is capitalized as a visual effect.
This effect cannot be written into the source document
because the position of the line break depends on layout.
But also, the capitalization is not reflecting a semantic distinction
and is not intended to affect the paragraph’s reading;
therefore it belongs in the presentation layer.
In this example,
the [=ruby=] annotations,
which are half the size of the main paragraph text,
are transformed to use regular-size kana
in place of [=small kana=].
Note that while this makes such letters easier to see at small type sizes,
the transformation distorts the text:
the reader needs to mentally substitute [=small kana=]
in the appropriate places--
not unlike reading a Latin inscription
where all “U”s look like “V”s.
For example, if ''text-transform: full-size-kana'' were applied to the following source,
the annotation would read “じゆう” (jiyū), which means “liberty”,
instead of “じゅう” (jū), which means “ten”,
the correct reading and meaning for the annotated “十”.
<ruby>十<rt>じゅう</ruby>
Mapping Rules
For ''capitalize'', what constitutes a “word“ is UA-dependent;
[[!UAX29]] is suggested (but not required)
for determining such word boundaries.
Out-of-flow elements and inline element boundaries
must not introduce a 'text-transform' word boundary
and must be ignored when determining such word boundaries.
text-transform/text-transform-capitalize-033.html
text-transform/text-transform-capitalize-034.html
text-transform/text-transform-capitalize-035.html
Note: Authors cannot depend on ''capitalize'' to follow
language-specific titlecasing conventions
(such as skipping articles in English).
The UA must use the full case mappings for Unicode characters,
including any conditional casing rules,
as defined in the Default Case Algorithms section of The Unicode Standard.
[[!UNICODE]]
If (and only if) the [=content language=] of the element is,
according to the rules of the [=document language=],
known,
then any appropriate language-specific rules must be applied as well.
These minimally include,
but are not limited to,
the language-specific rules in Unicode’s
SpecialCasing.txt.
writing-system/writing-system-text-transform-001.html
text-transform/text-transform-tailoring-001.html
text-transform/text-transform-tailoring-002.html
text-transform/text-transform-tailoring-002a.html
text-transform/text-transform-tailoring-003.html
text-transform/text-transform-tailoring-004.html
text-transform/text-transform-tailoring-005.html
text-transform/text-transform-upperlower-032.html
text-transform/text-transform-upperlower-033.html
text-transform/text-transform-upperlower-034.html
text-transform/text-transform-upperlower-035.html
text-transform/text-transform-upperlower-038.html
text-transform/text-transform-upperlower-039.html
text-transform/text-transform-upperlower-040.html
text-transform/text-transform-upperlower-041.html
text-transform/text-transform-upperlower-042.html
text-transform/text-transform-upperlower-043.html
For example, in Turkish there are two “i”s,
one with a dot--
“İ” and “i”--
and one without--
“I” and “ı”.
Thus the usual case mappings between “I” and “i”
are replaced with a different set of mappings
to their respective dotless/dotted counterparts,
which do not exist in English.
This mapping must only take effect
if the [=content language=] is Turkish
written in its modern Latin-based [=writing system=]
(or another Turkic language that uses Turkish casing rules);
in other languages,
the usual mapping of “I” and “i” is required.
This rule is thus conditionally defined in Unicode’s SpecialCasing.txt file.
text-transform-bicameral-005.xht
text-transform-bicameral-006.xht
The definition of full-width and half-width forms
can be found in Unicode Standard Annex #11: East Asian Width.
[[!UAX11]]
The mapping to [=full-width=] form is defined
by taking code points with the <wide>
or the <narrow> tag
in their Decomposition_Mapping
in Unicode Standard Annex #44: Unicode Character Database.
[[!UAX44]]
For the <narrow> tag,
the mapping is from the code point to the decomposition
(minus <narrow> tag),
and for the <wide> tag,
the mapping is from the decomposition
(minus the <wide> tag)
back to the original code point.
text-transform/text-transform-fullwidth-001.xht
text-transform/text-transform-fullwidth-002.xht
text-transform/text-transform-fullwidth-004.xht
text-transform/text-transform-fullwidth-005.xht
text-transform/text-transform-fullwidth-006.html
text-transform/text-transform-fullwidth-007.html
The mappings for [=small Kana=] to [=full-size Kana=] are defined in [[#small-kana]].
Expanding Between Words: the 'word-space-transform' property
Name: word-space-transform
Value: none | [ space | ideographic-space ] && auto-phrase?
Initial: none
Applies to: text
Inherited: yes
Percentages: N/A
Computed value: as specified
Animation type: discrete
parsing/word-space-transform-computed.html
parsing/word-space-transform-invalid.html
parsing/word-space-transform-valid.html
word-space-transform/word-space-transform-003.html
word-space-transform/word-space-transform-004.html
word-space-transform/word-space-transform-005.html
word-space-transform/word-space-transform-006.html
Some languages and writing systems have alternative ways
of delimiting words,
either using different separating characters,
or sometimes no visible character at all.
This property allows authors to change the rendering
from one style to another
without needing to change the markup.
none
This property has no effect.
word-space-transform/word-space-transform-004.html
word-space-transform/word-space-transform-005.html
space
[=Expandable separators=]
within the child [=text sequence|text=] of this element
are replaced by U+0020 SPACE.
word-space-transform/word-space-transform-002.html
word-space-transform/word-space-transform-004.html
word-space-transform/word-space-transform-005.html
word-space-transform/word-space-transform-006.html
word-space-transform/word-space-transform-007.html
word-space-transform/word-space-transform-008.html
word-space-transform/word-space-transform-009.html
word-space-transform/word-space-transform-014.html
word-space-transform/word-space-transform-015-manual.html
word-space-transform/word-space-transform-017.html
word-space-transform/word-space-transform-018.html
ideographic-space
[=Expandable separators=]
within the child [=text sequence|text=] of this element
are replaced by U+3000 IDEOGRAPHIC SPACE.
word-space-transform/word-space-transform-001.html
word-space-transform/word-space-transform-003.html
word-space-transform/word-space-transform-010.html
word-space-transform/word-space-transform-011.html
word-space-transform/word-space-transform-012.html
word-space-transform/word-space-transform-013.html
word-space-transform/word-space-transform-016.html
word-space-transform/word-space-transform-019.html
word-space-transform/word-space-transform-020.html
word-space-transform/word-space-transform-021.html
word-space-transform/word-space-transform-022.html
word-space-transform/word-space-transform-023.html
word-space-transform/word-space-transform-024.html
word-space-transform/word-space-transform-025.html
word-space-transform/word-space-transform-026.html
auto-phrase
If the [=content language=] is known
and the user agent supports linguistic analysis for this language,
the user agent must [=detect phrase boundaries=].
If a [=word-separator character=],
[=other space separator=],
or U+200B ZERO WIDTH SPACE character
does not already occur at that boundary,
then the UA must insert a [=virtual expandable separator=].
word-space-transform/word-space-transform-016.html
word-space-transform/word-space-transform-017.html
word-space-transform/word-space-transform-018.html
word-space-transform/word-space-transform-019.html
word-space-transform/word-space-transform-020.html
word-space-transform/word-space-transform-021.html
word-space-transform/word-space-transform-022.html
word-space-transform/word-space-transform-023.html
word-space-transform/word-space-transform-024.html
word-space-transform/word-space-transform-025.html
word-space-transform/word-space-transform-026.html
If this value is omitted,
or if the [=content language=] is unknown,
or if the user agent does not support
[=detecting phrase boundaries=] for that language,
there are no [=virtual expandable separator=].
word-space-transform/word-space-transform-027.html
word-space-transform/word-space-transform-028.html
word-space-transform/word-space-transform-029.html
For the purpose of this property,
expandable separators are any of:
* U+200B ZERO WIDTH SPACE characters
word-space-transform/word-space-transform-001.html
word-space-transform/word-space-transform-002.html
word-space-transform/word-space-transform-003.html
word-space-transform/word-space-transform-004.html
word-space-transform/word-space-transform-005.html
word-space-transform/word-space-transform-006.html
word-space-transform/word-space-transform-007.html
word-space-transform/word-space-transform-008.html
word-space-transform/word-space-transform-009.html
word-space-transform/word-space-transform-010.html
word-space-transform/word-space-transform-011.html
word-space-transform/word-space-transform-012.html
word-space-transform/word-space-transform-015-manual.html
* <{wbr}> elements
word-space-transform/word-space-transform-001.html
word-space-transform/word-space-transform-002.html
word-space-transform/word-space-transform-003.html
word-space-transform/word-space-transform-004.html
word-space-transform/word-space-transform-006.html
word-space-transform/word-space-transform-007.html
word-space-transform/word-space-transform-008.html
word-space-transform/word-space-transform-009.html
word-space-transform/word-space-transform-010.html
word-space-transform/word-space-transform-011.html
word-space-transform/word-space-transform-012.html
word-space-transform/word-space-transform-013.html
word-space-transform/word-space-transform-014.html
word-space-transform/word-space-transform-015-manual.html
* [=virtual expandable separators=]
word-space-transform/word-space-transform-016.html
word-space-transform/word-space-transform-017.html
word-space-transform/word-space-transform-018.html
word-space-transform/word-space-transform-019.html
word-space-transform/word-space-transform-020.html
A virtual expandable separator is
a UA-detected syntactic boundary in the text
that represents an [=expandable separator=]
not otherwise occuring in the source document.
It has no effect other than for this property.
The user agent must not replace
[=expandable separators=]
immediately preceding or following
a [=forced line break=]
(ignoring any intervening inline box boundaries,
and associated 'margin'/'border'/'padding').
word-space-transform/word-space-transform-010.html
word-space-transform/word-space-transform-011.html
word-space-transform/word-space-transform-012.html
Note: Because [=virtual expandable separators=]
are placed in the outermost element that participates in an inline box boundary,
if one would coincide with boundary of an inline box
whose parent box has a [=used value=]
of ''word-space-transform: none'',
that particular [=virtual expandable separator=] is not expanded,
since it would be placed in the parent box.
word-space-transform/word-space-transform-020.html
Like 'text-transform', this property transforms text for styling purposes only.
It has no effect on the underlying content,
and must not affect the content of a plain text copy & paste operation.
word-space-transform/word-space-transform-015-manual.html
Unlike books for adults, Japanese books for young children often feature spaces between sentence segments,
to facilitate reading.
People with dyslexia also tend to find this style easier to read.
Absent any particular styling, the following sentence would be rendered as depicted below.
むかしむかし、あるところに、おじいさんとおばあさんがすんでいました。
Phrase-based spacing can be achieved with the following css:
p {
word-space-transform: ideographic-space;
}
むかしむかし、 あるところに、 おじいさんと おばあさんが すんでいました。
Another common variant additionally restricts the allowable line breaks to these phrase boundaries.
Using the same markup, this is easily achieved with the following css:
p {
word-break: keep-all;
word-space-transform: ideographic-space;
}
In addition to making the source code more readable,
using <{wbr}> rather than U+200B in the markup
also allow authors to classify the delimiters into different groups.
In the following example,
<{wbr}> elements are either
unmarked when they delimit a word,
or marked with class p when they also delimit a phrase.
Using this, it is possible not only to enable the rather common phrase-based spacing,
but also word-by-word spacing
that is likely to be preferred
by people with dyslexia to reduce ambiguities,
or other variants
such as a combination of phrase-based spacing and of word-based wrapping.
Usual rendering
らいしゅうのじゅぎょうにたいことばちをもってきてください。
Phrase spacing
p wbr.p {
word-space-transform: ideographic-space;
}
らいしゅうのじゅぎょうに たいことばちを もってきてください。
Word spacing
p wbr {
word-space-transform: ideographic-space;
}
p {
word-break: keep-all;
}
p wbr.p {
word-space-transform: ideographic-space;
}
らいしゅうのじゅぎょうに たいことばちを もってきてください。
Word spacing and wrapping
p {
word-break: keep-all;
}
p wbr {
word-space-transform: ideographic-space;
}
らいしゅう の じゅぎょう に たいこ と ばち を もって きて ください。
Order of Operations
When multiple transformations need to be applied,
they are applied in the following order:
'word-space-transform'
''capitalize'', ''uppercase'', and ''lowercase''
''full-width''
''full-size-kana''
text-transform/text-transform-multiple-001.html
Word space transformation and
text transformation happen after [[#white-space-phase-1]]
but before [[#white-space-phase-2]].
This means for instance that ''full-width'' only transforms
spaces (U+0020) to U+3000 IDEOGRAPHIC SPACE within [=preserved=] [=white space=].
text-transform/text-transform-fullwidth-006.html
text-transform/text-transform-fullwidth-007.html
text-transform/text-transform-fullwidth-008.html
text-transform/text-transform-fullwidth-009.html
word-space-transform/word-space-transform-007.html
word-space-transform/word-space-transform-008.html
word-space-transform/word-space-transform-009.html
Note: As defined in [[#order]],
transforming affects line-breaking and other formatting operations.
word-space-transform/word-space-transform-030.html
White Space and Wrapping: the 'white-space' property
Name: white-space
Value: normal | pre | pre-wrap | pre-line | <<'white-space-collapse'>> || <<'text-wrap-mode'>> || <<'white-space-trim'>>
Initial: normal
Applies to: text
Inherited: see individual properties
Canonical order: n/a
Computed value: specified keyword
Animation type: discrete
inheritance.html
parsing/white-space-valid.html
parsing/white-space-invalid.html
parsing/white-space-computed.html
parsing/white-space-shorthand.html
white-space/ws-break-spaces-applies-to-001.html
white-space/ws-break-spaces-applies-to-002.html
white-space/ws-break-spaces-applies-to-003.html
white-space/ws-break-spaces-applies-to-005.html
white-space/ws-break-spaces-applies-to-006.html
white-space/ws-break-spaces-applies-to-007.html
white-space/ws-break-spaces-applies-to-008.html
white-space/ws-break-spaces-applies-to-009.html
white-space/ws-break-spaces-applies-to-010.html
white-space/ws-break-spaces-applies-to-011.html
white-space/ws-break-spaces-applies-to-012.html
white-space/ws-break-spaces-applies-to-013.html
white-space/ws-break-spaces-applies-to-014.html
white-space/ws-break-spaces-applies-to-015.html
white-space/white-space-applies-to-text-001.html
white-space/white-space-pre-031.html
white-space/white-space-pre-032.html
white-space/white-space-pre-034.html
white-space/white-space-pre-035.html
c562-white-sp-000.xht
white-space-006.xht
white-space-007.xht
white-space-applies-to-001.xht
white-space-applies-to-002.xht
white-space-applies-to-002.xht
white-space-applies-to-003.xht
white-space-applies-to-005.xht
white-space-applies-to-006.xht
white-space-applies-to-007.xht
white-space-applies-to-008.xht
white-space-applies-to-009.xht
white-space-applies-to-010.xht
white-space-applies-to-011.xht
white-space-applies-to-012.xht
white-space-applies-to-013.xht
white-space-applies-to-014.xht
white-space-applies-to-015.xht
white-space-mixed-001.xht
white-space-mixed-002.xht
white-space-mixed-003.xht
white-space-mixed-004.xht
This property is a shorthand for 'white-space-collapse', 'text-wrap-mode', and 'white-space-trim'.
It specifies two things:
whether and how [=white space=] is collapsed;
see [[#white-space-processing|White Space Processing]]
whether lines may [=wrap=] at unforced [=soft wrap opportunities=];
see [[#text-wrapping]] and [[#line-breaking|Line Breaking]]
Note: This shorthand combines both inheritable and non-inheritable properties.
If this is a problem, please inform the CSSWG.
Unless otherwise specified, any omitted [=longhand=]
is set to its [=initial value=].
The following table gives the normative mapping
of the values of the [=shorthand=]’s special keywords
to their equivalent [=longhand=] values.
'white-space'
'white-space-collapse'
'text-wrap-mode'
'white-space-trim'
normal
''white-space-collapse/collapse''
''text-wrap-mode/wrap''
''white-space-trim/none''
pre
''white-space-collapse/preserve''
''text-wrap-mode/nowrap''
''white-space-trim/none''
pre-wrap
''white-space-collapse/preserve''
''text-wrap-mode/wrap''
''white-space-trim/none''
pre-line
''white-space-collapse/preserve-breaks''
''text-wrap-mode/wrap''
''white-space-trim/none''
Note: In some cases,
[=preserved white space=] and [=other space separators=]
can [=hang=] when at the end of the line;
this can affect whether they are measured for [=intrinsic sizing=].
The following informative table summarizes the behavior
of various 'white-space' values:
New Lines
Spaces and Tabs
Text Wrapping
End-of-line [=spaces=]
End-of-line [=other space separators=]
''white-space/normal''
Collapse
Collapse
Wrap
Remove
Hang
''pre''
Preserve
Preserve
No wrap
Preserve
No wrap
''white-space/nowrap''
Collapse
Collapse
No wrap
Remove
Hang
''pre-wrap''
Preserve
Preserve
Wrap
Hang
Hang
''break-spaces''
Preserve
Preserve
Wrap
Wrap
Wrap
''pre-line''
Preserve
Collapse
Wrap
Remove
Hang
White Space Processing & Control Characters
The source text of a document often contains formatting
that is not relevant to the final rendering:
for example,
breaking the source into segments
(lines) for ease of editing
or adding [=white space characters=] such as [=tabs=] and [=spaces=]
to indent the source code.
CSS white space processing allows the author
to control interpretation of such formatting:
to preserve or collapse it away when rendering the document.
White space processing in CSS
(which is controlled with the 'white-space-collapse' and 'white-space-trim' properties)
interprets [=white space characters=] only for rendering:
it has no effect on the underlying document data.
Note: Depending on the document language,
segments can be separated by a particular newline sequence
(such as a line feed or CRLF pair),
or delimited by some other mechanism,
such as the SGML RECORD-START and RECORD-END tokens.
For CSS processing,
each document language–defined “segment break” or “newline sequence”--
or if none are defined, each line feed (U+000A)--
in the text is treated as a segment break,
which is then interpreted for rendering as specified by the 'white-space' property.
In the case of HTML,
[[html#newlines|newlines]] are [=normalize newlines|normalized=] to line feed characters (U+000A)
for representation in the DOM,
so when an HTML document is represented as a DOM tree
each line feed (U+000A)
is treated as a [=segment break=].
[[HTML]]
[[DOM]]
Note: In most common CSS implementations,
HTML does not get styled directly.
Instead, it is processed into a DOM tree,
which is then styled.
Unlike HTML,
the DOM does not give any particular meaning to carriage returns (U+000D),
so they are not treated as [=segment breaks=].
If carriage returns (U+000D) are inserted into the DOM
by means other than HTML parsing,
they then get treated as defined below.
white-space-processing-005.xht
white-space-processing-006.xht
white-space-processing-007.xht
Note: A document parser might
not only normalize any [=segment breaks=],
but also collapse other space characters or
otherwise process white space according to markup rules.
Because CSS processing occurs after the parsing stage,
it is not possible to restore these characters for styling.
Therefore, some of the behavior specified below
can be affected by these limitations and
may be user agent dependent.
Note: Anonymous blocks consisting entirely of [=collapsible=] [=white space=]
are removed from the rendering tree.
Thus any such [=white space=] surrounding a block-level element is collapsed away.
See [[CSS2/visuren#anonymous]].
[[CSS2]]
Control characters ([=Unicode category=] Cc)--
other than tabs (U+0009),
line feeds (U+000A),
carriage returns (U+000D)
and sequences that form a [=segment break=]--
must be rendered as a visible glyph
which the UA must synthesize if the glyphs found in the font are not visible,
and must be otherwise treated as any other character
of the Other Symbols (So) [=general category=] and Common [=Unicode Script|script=].
The UA may use a glyph provided by a font specifically for the control character,
substitute the glyphs provided for the corresponding symbol in the Control Pictures block,
generate a visual representation of its code point value,
or use some other method to provide an appropriate visible glyph.
As required by Unicode,
unsupported Default_ignorable characters
must be ignored for text rendering.
[[!UNICODE]]
white-space/control-chars-000.html
white-space/control-chars-001.html
white-space/control-chars-002.html
white-space/control-chars-003.html
white-space/control-chars-004.html
white-space/control-chars-005.html
white-space/control-chars-006.html
white-space/control-chars-007.html
white-space/control-chars-008.html
white-space/control-chars-00B.html
white-space/control-chars-00C.html
white-space/control-chars-00D.html
white-space/control-chars-00E.html
white-space/control-chars-00F.html
white-space/control-chars-010.html
white-space/control-chars-011.html
white-space/control-chars-012.html
white-space/control-chars-013.html
white-space/control-chars-014.html
white-space/control-chars-015.html
white-space/control-chars-016.html
white-space/control-chars-017.html
white-space/control-chars-018.html
white-space/control-chars-019.html
white-space/control-chars-01A.html
white-space/control-chars-01B.html
white-space/control-chars-01C.html
white-space/control-chars-01D.html
white-space/control-chars-01E.html
white-space/control-chars-01F.html
white-space/control-chars-07F.html
white-space/control-chars-080.html
white-space/control-chars-081.html
white-space/control-chars-082.html
white-space/control-chars-083.html
white-space/control-chars-084.html
white-space/control-chars-085.html
white-space/control-chars-086.html
white-space/control-chars-087.html
white-space/control-chars-088.html
white-space/control-chars-089.html
white-space/control-chars-08A.html
white-space/control-chars-08B.html
white-space/control-chars-08C.html
white-space/control-chars-08D.html
white-space/control-chars-08E.html
white-space/control-chars-08F.html
white-space/control-chars-090.html
white-space/control-chars-091.html
white-space/control-chars-092.html
white-space/control-chars-093.html
white-space/control-chars-094.html
white-space/control-chars-095.html
white-space/control-chars-096.html
white-space/control-chars-097.html
white-space/control-chars-098.html
white-space/control-chars-099.html
white-space/control-chars-09A.html
white-space/control-chars-09B.html
white-space/control-chars-09C.html
white-space/control-chars-09D.html
white-space/control-chars-09E.html
white-space/control-chars-09F.html
control-characters-001.html
control-characters-002.xht
white-space-control-characters-001.xht
Carriage returns (U+000D) are treated identically to spaces (U+0020) in all respects.
white-space/control-chars-00D.html
white-space-processing-005.xht
white-space-processing-006.xht
white-space-processing-007.xht
Note: For HTML documents,
carriage returns present in the source code
are converted to line feeds at the parsing stage
(see [[HTML#preprocessing-the-input-stream]]
and the definition of [=normalize newlines=] in Infra
and therefore do no appear as U+000D CARRIAGE RETURN to CSS.
[[HTML]]
[[INFRA]])
However, the character is preserved--
and the above rule observable--
when encoded using an escape sequence (
).
White Space Collapsing: the 'white-space-collapse' property
ISSUE: This section is still under discussion and may change in future drafts.
inheritance.html
parsing/white-space-collapse-valid.html
parsing/white-space-collapse-computed.html
parsing/white-space-collapse-invalid.html
This property specifies whether and how
white space
is collapsed.
Values have the following meanings,
which must be interpreted according to
the [[#white-space-rules|White Space Processing Rules]]:
This value prevents user agents
from collapsing sequences of [=white space=],
and converts [=tabs=] and [=segment breaks=] to [=spaces=].
(This value is intended to represent the behavior
of xml:space="preserve" in SVG.)
break-spaces
The behavior is identical to that of ''preserve'',
except that:
Any sequence of [=preserved=] [=white space=]
or [=other space separators=]
always takes up space,
including at the end of the line.
white-space/white-space-intrinsic-size-001.html
white-space/white-space-intrinsic-size-002.html
white-space/white-space-intrinsic-size-021.html
Note: This value does not guarantee
that there will never be any overflow due to white space:
for example, if the line length is so short
that even a single white space character does not fit,
overflow is unavoidable.
discard
This value directs user agents to “discard”
all white space in the element.
white-space/white-space-collapse-discard-001.xht
Issue: Does this preserve line break opportunities or no? Do we need a distinct "hide" value?
If it preserves line break opportunities,
maybe it should be replaced with a 'word-space-transform' value?
[=White space=] that was not removed or collapsed due to white space processing
is called preserved white space.
The following style rules implement MathML's white space processing:
White Space Trimming: the 'white-space-trim' property
Name: white-space-trim
Value: none | discard-before || discard-after || discard-inner
Initial: none
Applies to: [=inline boxes=] and [=block containers=]
Inherited: no
Percentages: n/a
Computed value: specified keyword(s)
Animation type: discrete
This property allows authors to specify trimming behavior
at the beginning and end of a box.
Values have the following meanings:
discard-before
This value directs the UA to collapse all collapsible whitespace
immediately before the start of the element.
discard-after
This value directs the UA to collapse all collapsible whitespace
immediately after the end of the element.
discard-inner
For block containers this value directs UAs to discard
all whitespace at the beginning of the element up to and including
the last segment break before the first non-white-space character in the element
as well as to discard all white space at the end of the element
starting with the first segment break after the last non-white-space character in the element.
For other elements this value directs UAs to discard
all whitespace at the beginning and end of the element.
white-space/white-space-trim-discard-inner-001.xht
Note: Discarding [=document white space=] using 'white-space-trim'
can change where [=soft wrap opportunities=] occur in the text.
The following style rules render DT elements as a comma-separated list,
even if they are coded on separate lines of the source document:
The following style rule removes source-formatting white space
adjacent to the opening/closing tags of a preformatted block,
but not any indentation or interleaved white space
applied to the actual contents of the element:
pre { white-space: pre; white-space-trim: discard-inner; }
This results in the following two source-code snippets:
<pre>
some
preformatted
text
</pre>
<pre> some
preformatted
text</pre>
start[<span>
some
inline
text
</span>]end
start[<span> some
inline
text</span>]end
this directs the UA to discard all of the leading/trailing white space
before the actual contents of the element:
start[some inline text]end
White space processing for 'white-space-trim'
takes place before [[#white-space-phase-1]].
The White Space Processing Rules
Except where specified otherwise,
white space processing in CSS affects only
the document white space characters:
spaces (U+0020), tabs (U+0009), and [[#white-space-processing|segment breaks]].
white-space-normal-003.xht
white-space-normal-004.xht
white-space-normal-005.xht
white-space-normal-006.xht
white-space-normal-007.xht
white-space-normal-008.xht
white-space-nowrap-005.xht
white-space-nowrap-006.xht
white-space-pre-005.xht
white-space-pre-006.xht
white-space-processing-054.xht
white-space-processing-055.xht
white-space-processing-056.xht
white-space/display-contents-remove-whitespace-change.html
white-space/remove-slotted-with-whitespace-sibling.html
Note: The set of characters considered [=document white space=]
(part of the document content)
and those considered syntactic white space
(part of the CSS syntax)
are not necessarily identical.
However, since both include spaces (U+0020), tabs (U+0009), and line feeds (U+000A)
most authors won’t notice any differences.
Besides space (U+0020)
and no-break space (U+00A0),
Unicode defines a number of additional space separator characters.
[[UNICODE]]
In this specification
all characters in the Unicode [=general category=] Zs
except space (U+0020)
and no-break space (U+00A0)
are collectively referred to as
other space separators.
white-space/trailing-other-space-separators-001.html
white-space/trailing-other-space-separators-002.html
white-space/trailing-other-space-separators-003.html
white-space/trailing-other-space-separators-004.html
white-space/trailing-other-space-separators-break-spaces-001.html
white-space/trailing-other-space-separators-break-spaces-002.html
white-space/trailing-other-space-separators-break-spaces-003.html
white-space/trailing-other-space-separators-break-spaces-004.html
white-space/trailing-other-space-separators-break-spaces-005.html
white-space/trailing-other-space-separators-break-spaces-006.html
white-space/trailing-other-space-separators-break-spaces-007.html
white-space/trailing-other-space-separators-break-spaces-008.html
white-space/trailing-other-space-separators-break-spaces-009.html
white-space/trailing-other-space-separators-break-spaces-010.html
white-space/trailing-other-space-separators-break-spaces-011.html
white-space/trailing-other-space-separators-break-spaces-012.html
white-space/trailing-other-space-separators-break-spaces-013.html
white-space/trailing-other-space-separators-break-spaces-014.html
white-space/trailing-other-space-separators-break-spaces-015.html
Phase I: Collapsing and Transformation
Note: 'white-space-trim' is taken into account prior to this phase.
For each inline
(including anonymous inlines;
see [[CSS2/visuren#anonymous]] [[CSS2]])
within an [=inline formatting context=],
[=white space characters=] are processed as follows
prior to [=line breaking=] and [[css-writing-modes-4#text-direction|bidi reordering]],
ignoring bidi formatting characters
(characters with the Bidi_Control property [[!UAX9]])
as if they were not there:
white-space/white-space-collapse-002.html
white-space/white-space-normal-011.html
white-space/white-space-nowrap-011.html
If 'white-space-collapse' is set to ''white-space-collapse/collapse'' or ''preserve-breaks'',
[=white space characters=] are considered collapsible
and are processed by performing the following steps:
Any sequence of collapsible [=spaces=] and [=tabs=]
immediately preceding or following a [=segment break=]
is removed.
white-space/white-space-normal-011.html
white-space/white-space-nowrap-011.html
line-breaking/segment-break-transformation-unremovable-3.html
line-breaking/segment-break-transformation-unremovable-4.html
white-space-processing-002.xht
white-space-processing-003.xht
white-space-processing-004.xht
white-space-processing-008.xht
white-space-processing-009.xht
white-space-processing-010.xht
white-space-processing-005.xht
white-space-processing-006.xht
white-space-processing-007.xht
Collapsible [=segment breaks=] are transformed for rendering
according to the [[#line-break-transform|segment break transformation rules]].
Every [=collapsible=] [=tab=] is converted to a collapsible space (U+0020).
white-space/white-space-collapse-000.html
white-space/white-space-normal-011.html
white-space/white-space-nowrap-011.html
white-space-processing-019.xht
white-space-processing-020.xht
white-space-processing-021.xht
Any [=collapsible=] [=space=] immediately following another [=collapsible=] [=space=]--
even one outside the boundary of the inline containing that [=space=],
provided both [=spaces=] are within the same inline formatting context--
is collapsed to have zero advance width.
(It is invisible,
but retains its [=soft wrap opportunity=],
if any.)
white-space/white-space-collapse-001.html
white-space/white-space-empty-text-sibling.html
white-space/white-space-normal-011.html
white-space/white-space-nowrap-011.html
white-space-001.xht
white-space-003.xht
white-space-005.xht
white-space-collapsing-001.xht
white-space-collapsing-002.xht
white-space-collapsing-004.xht
white-space-collapsing-005.xht
white-space-collapsing-breaks-001.xht
white-space-mixed-001.xht
white-space-mixed-002.xht
white-space-normal-001.xht
white-space-processing-001.xht
white-space-processing-022.xht
white-space-processing-023.xht
white-space-processing-024.xht
white-space-processing-025.xht
white-space-processing-026.xht
white-space-processing-027.xht
white-space-processing-028.xht
white-space-processing-029.xht
white-space-processing-030.xht
white-space-processing-031.xht
white-space-processing-032.xht
white-space-processing-033.xht
white-space-processing-034.xht
white-space-processing-035.xht
white-space-processing-036.xht
white-space-processing-050.xht
white-space-processing-051.xht
white-space-processing-053.xht
If 'white-space-collapse' is set to ''preserve-spaces'',
each [=tab=] and [=segment break=] is converted to a [=space=].
If 'white-space-collapse' is set to ''preserve'' or ''preserve-spaces'',
any sequence of spaces is treated as a sequence of non-breaking spaces
except that
a [=soft wrap opportunity=] exists at the end of each maximal sequence of [=spaces=] and/or [=tabs=].
For ''break-spaces'',
a [=soft wrap opportunity=] exists after every [=space=] and every [=tab=].
white-space/white-space-pre-011.html
overflow-wrap/overflow-wrap-break-word-004.html
overflow-wrap/overflow-wrap-break-word-005.html
overflow-wrap/overflow-wrap-break-word-006.html
overflow-wrap/overflow-wrap-break-word-007.html
overflow-wrap/overflow-wrap-anywhere-004.html
overflow-wrap/overflow-wrap-anywhere-005.html
word-break/word-break-break-all-011.html
word-break/word-break-break-all-012.html
word-break/word-break-break-all-013.html
word-break/word-break-break-all-015.html
white-space/break-spaces-006.html
white-space/break-spaces-007.html
white-space/break-spaces-008.html
white-space/break-spaces-009.html
white-space/break-spaces-010.html
white-space/break-spaces-before-first-char-001.html
white-space/break-spaces-before-first-char-002.html
white-space/break-spaces-before-first-char-003.html
white-space/break-spaces-before-first-char-004.html
white-space/break-spaces-before-first-char-005.html
white-space/break-spaces-before-first-char-006.html
white-space/break-spaces-before-first-char-011.html
white-space/break-spaces-before-first-ideographic-char-001.html
white-space/break-spaces-before-first-ideographic-char-002.html
white-space/break-spaces-before-first-ideographic-char-003.html
white-space/break-spaces-before-first-ideographic-char-004.html
white-space/break-spaces-before-first-ideographic-char-005.html
white-space/break-spaces-before-first-ideographic-char-006.html
white-space/break-spaces-before-first-ideographic-char-011.html
white-space/pre-wrap-008.html
white-space/pre-wrap-015.html
white-space/pre-wrap-016.html
white-space/pre-wrap-leading-spaces-001.html
white-space/pre-wrap-leading-spaces-002.html
white-space/pre-wrap-leading-spaces-003.html
white-space/pre-wrap-leading-spaces-004.html
white-space/pre-wrap-leading-spaces-005.html
white-space/pre-wrap-leading-spaces-006.html
white-space/pre-wrap-leading-spaces-007.html
white-space/pre-wrap-leading-spaces-008.html
white-space/pre-wrap-leading-spaces-009.html
white-space/pre-wrap-leading-spaces-010.html
white-space/pre-wrap-leading-spaces-011.html
white-space/pre-wrap-leading-spaces-012.html
white-space/pre-wrap-leading-spaces-013.html
white-space/pre-wrap-leading-spaces-014.html
white-space/break-spaces-tab-001.html
white-space/break-spaces-tab-002.html
white-space/break-spaces-tab-003.html
white-space/break-spaces-tab-004.html
white-space/pre-wrap-tab-001.html
white-space/pre-wrap-tab-002.html
white-space/pre-wrap-tab-003.html
white-space/pre-wrap-tab-004.html
white-space-002.xht
white-space-004.xht
white-space-processing-011.xht
white-space-processing-012.xht
white-space-processing-013.xht
white-space-processing-052.xht
The following example illustrates
the interaction of white-space collapsing and bidirectionality.
Consider the following markup fragment, taking special note of [=spaces=]
(with varied backgrounds and borders for emphasis and identification):
<ltr>A<rtl>B</rtl>C</ltr>
where the <ltr> element represents a left-to-right embedding
and the <rtl> element represents a right-to-left embedding.
If the 'white-space' property is set to ''white-space/normal'',
the white-space processing model will result in the following:
The [=space=] before the B ()
will collapse with the [=space=] after the A ().
The [=space=] before the C ()
will collapse with the [=space=] after the B ().
This will leave two [=spaces=],
one after the A in the left-to-right embedding level,
and one after the B in the right-to-left embedding level.
The text will then be ordered according to the Unicode bidirectional algorithm,
with the end result being:
ABC
Note that there will be two [=spaces=] between A and B,
and none between B and C.
This is best avoided by putting [=spaces=] outside the element
instead of just inside the opening and closing tags
and, where practical,
by relying on implicit bidirectionality instead of explicit embedding levels.
white-space-bidirectionality-001.xht
Phase II: Trimming and Positioning
Then, the entire block is rendered.
Inlines are laid out,
taking [[css-writing-modes-4#text-direction|bidi reordering]] into account,
and [=wrapping=] as specified by the 'text-wrap-mode' and 'text-wrap-style' property.
As each line is laid out,
A sequence of [=collapsible=] [=spaces=] at the beginning of a line
is removed.
white-space/line-edge-white-space-collapse-002.html
white-space/break-spaces-051.html
white-space/break-spaces-052.html
white-space/pre-line-051.html
white-space/pre-line-052.html
white-space/pre-wrap-051.html
white-space/pre-wrap-052.html
white-space/white-space-pre-051.html
white-space/white-space-pre-052.html
white-space/full-width-leading-spaces-001.html
white-space/full-width-leading-spaces-002.html
white-space/full-width-leading-spaces-003.html
white-space-collapsing-003.xht
white-space-collapsing-bidi-003.xht
white-space-normal-001.xht
white-space-normal-002.xht
white-space-processing-037.xht
white-space-processing-038.xht
white-space-processing-039.xht
white-space-processing-040.xht
white-space-processing-041.xht
If the [=tab size=] is zero,
[=preserved=] [=tabs=] are not rendered.
Otherwise, each [=preserved=] [=tab=] is rendered
as a horizontal shift that lines up
the start edge of the next glyph with the next [=tab stop=].
If this distance is less than ''0.5ch'',
then the subsequent [=tab stop=] is used instead.
Tab stops occur at points
that are multiples of the [=tab size=]
from the starting content edge
of the [=preserved=] [=tab=]’s nearest [=block container=] ancestor.
The [=tab size=] is given by the 'tab-size' property.
white-space/tab-stop-threshold-001.html
white-space/tab-stop-threshold-002.html
white-space/tab-stop-threshold-003.html
white-space/tab-stop-threshold-004.html
white-space/tab-stop-threshold-005.html
white-space/tab-stop-threshold-006.html
white-space/white-space-pre-011.html
tab-size/tab-min-rendered-width-1.html
tab-size/tab-size-integer-003.html
text-indent/text-indent-tab-positions-001.html
tab-size/tab-size-inline-002.html
white-space/white-space-zero-fontsize-002.html
white-space-processing-042.xht
Note: See the Unicode rules on how tabulation (U+0009) interacts with bidi. [[UAX9]]
bidi/bidi-tab-001.html
white-space/tab-bidi-001.html
A sequence of [=collapsible=] [=spaces=]
at the end of a line is removed,
as well as any trailing U+1680 OGHAM SPACE MARK
whose 'white-space-collapse' property is ''white-space-collapse/collapse'' or ''white-space-collapse/preserve-breaks''.
white-space/line-edge-white-space-collapse-001.html
white-space/pre-float-001.html
white-space/pre-wrap-float-001.html
white-space/trailing-space-before-br-001.html
white-space/trailing-ogham-001.html
white-space/trailing-ogham-002.html
white-space/trailing-ogham-003.html
overflow-wrap/overflow-wrap-anywhere-011.html
white-space-collapsing-003.xht
white-space-collapsing-bidi-003.xht
white-space-normal-001.xht
white-space-normal-002.xht
white-space-processing-005.xht
white-space-processing-043.xht
white-space-processing-044.xht
white-space-processing-045.xht
white-space-processing-046.xht
white-space-processing-047.xht
Note: Due to Unicode Bidirectional Algorithm rule L1,
a sequence of [=collapsible=] [=spaces=] located at the end of the line
prior to [[css-writing-modes-4#text-direction|bidi reordering]]
will also be at the end of the line after reordering.
[[UAX9]]
[[CSS-WRITING-MODES-4]]
white-space/eol-spaces-bidi-001.html
white-space/eol-spaces-bidi-003.html
white-space/trailing-space-rtl-001.html
If there remains any sequence of [=white space=],
[=other space separators=],
and/or [=preserved=] [=tabs=]
at the end of a line
(after [[css-writing-modes-4#text-direction|bidi reordering]] [[CSS-WRITING-MODES-4]]):
If 'white-space-collapse' is ''white-space-collapse/collapse'' or ''white-space-collapse/preserve-breaks'',
the UA must [=hang=] this sequence (unconditionally).
white-space/trailing-ideographic-space-001.html
white-space/trailing-ideographic-space-002.html
white-space/trailing-ideographic-space-005.html
white-space/trailing-ideographic-space-006.html
white-space/trailing-ideographic-space-007.html
white-space/trailing-ideographic-space-008.html
white-space/trailing-ideographic-space-009.html
white-space/trailing-ideographic-space-010.html
white-space/trailing-ideographic-space-011.html
white-space/trailing-ideographic-space-012.html
white-space/trailing-ideographic-space-013.html
white-space/trailing-ideographic-space-014.html
white-space/trailing-ideographic-space-015.html
white-space/trailing-ideographic-space-016.html
white-space/trailing-ideographic-space-017.html
white-space/trailing-ideographic-space-018.html
white-space/trailing-ideographic-space-019.html
white-space/trailing-ideographic-space-020.html
white-space/trailing-ideographic-space-021.html
white-space/trailing-ideographic-space-022.html
white-space/trailing-ideographic-space-023.html
white-space/trailing-ideographic-space-024.html
white-space/trailing-ideographic-space-025.html
white-space/trailing-other-space-separators-001.html
white-space/trailing-other-space-separators-003.html
white-space/trailing-other-space-separators-004.html
text-transform/text-transform-fullwidth-008.html
white-space/white-space-intrinsic-size-019.html
white-space/white-space-intrinsic-size-020.html
white-space/trailing-space-and-text-alignment-001.html
white-space/trailing-space-and-text-alignment-005.html
white-space/trailing-space-and-text-alignment-rtl-001.html
white-space/trailing-space-and-text-alignment-rtl-005.html
If 'white-space-collapse' is ''white-space-collapse/preserve''
and 'text-wrap-mode' is not ''text-wrap-mode/nowrap'',
the UA must (unconditionally) [=hang=] this sequence,
unless the sequence is followed by a [=forced line break=],
in which case it must [=conditionally hang=] the sequence instead.
It may also visually collapse the character advance widths
of any that would otherwise overflow.
white-space/pre-wrap-001.html
white-space/pre-wrap-002.html
white-space/pre-wrap-003.html
white-space/pre-wrap-004.html
white-space/pre-wrap-005.html
white-space/pre-wrap-006.html
white-space/pre-wrap-007.html
white-space/pre-wrap-011.html
white-space/pre-wrap-012.html
white-space/pre-wrap-013.html
white-space/pre-wrap-014.html
white-space/pre-wrap-017.html
white-space/pre-wrap-018.html
white-space/pre-wrap-019.html
white-space/pre-wrap-020.html
white-space/textarea-pre-wrap-001.html
white-space/textarea-pre-wrap-002.html
white-space/textarea-pre-wrap-003.html
white-space/textarea-pre-wrap-004.html
white-space/textarea-pre-wrap-005.html
white-space/textarea-pre-wrap-006.html
white-space/textarea-pre-wrap-007.html
white-space/textarea-pre-wrap-011.html
white-space/textarea-pre-wrap-012.html
white-space/textarea-pre-wrap-013.html
white-space/textarea-pre-wrap-014.html
white-space/trailing-ideographic-space-003.html
white-space/trailing-ideographic-space-004.html
white-space/white-space-pre-wrap-trailing-spaces-001.html
white-space/white-space-pre-wrap-trailing-spaces-002.html
white-space/white-space-pre-wrap-trailing-spaces-003.html
white-space/white-space-pre-wrap-trailing-spaces-004.html
white-space/white-space-pre-wrap-trailing-spaces-005.html
white-space/white-space-pre-wrap-trailing-spaces-006.html
white-space/white-space-pre-wrap-trailing-spaces-007.html
white-space/white-space-pre-wrap-trailing-spaces-008.html
white-space/white-space-pre-wrap-trailing-spaces-010.html
white-space/white-space-pre-wrap-trailing-spaces-011.html
white-space/white-space-pre-wrap-trailing-spaces-012.html
white-space/white-space-pre-wrap-trailing-spaces-013.html
white-space/white-space-pre-wrap-trailing-spaces-014.html
white-space/white-space-pre-wrap-trailing-spaces-015.html
white-space/white-space-intrinsic-size-003.html
white-space/white-space-intrinsic-size-004.html
white-space/white-space-intrinsic-size-005.html
white-space/white-space-intrinsic-size-006.html
white-space/pre-wrap-tab-005.html
white-space/pre-wrap-tab-006.html
white-space/trailing-other-space-separators-002.html
text-transform/text-transform-fullwidth-009.html
white-space/trailing-space-position-001.html
line-break/line-break-anywhere-and-white-space-006.html
line-break/line-break-anywhere-and-white-space-007.html
white-space/white-space-intrinsic-size-013.html
white-space/white-space-intrinsic-size-014.html
white-space/white-space-intrinsic-size-017.html
white-space/eol-spaces-bidi-002.html
white-space/trailing-space-in-inline-box.html
white-space/trailing-space-and-text-alignment-003.html
white-space/trailing-space-and-text-alignment-rtl-003.html
white-space/white-space-pre-wrap-trailing-spaces-021.html
white-space/white-space-pre-wrap-trailing-spaces-022.html
white-space/white-space-pre-wrap-trailing-spaces-023.html
overflow-wrap/overflow-wrap-min-content-size-009.html
text-justify/text-justify-and-trailing-spaces-001.html
text-justify/text-justify-and-trailing-spaces-002.html
text-justify/text-justify-and-trailing-spaces-003.html
text-justify/text-justify-and-trailing-spaces-004.html
text-justify/text-justify-and-trailing-spaces-005.html
text-justify/text-justify-and-trailing-spaces-006.html
white-space/pre-wrap-align-center-001.html
white-space/pre-wrap-align-center-002.html
white-space/pre-wrap-align-center-003.html
white-space/pre-wrap-align-end-001.html
white-space/pre-wrap-align-end-002.html
white-space/pre-wrap-align-end-003.html
white-space/pre-wrap-align-left-001.html
white-space/pre-wrap-align-left-002.html
white-space/pre-wrap-align-left-003.html
white-space/pre-wrap-align-right-001.html
white-space/pre-wrap-align-right-002.html
white-space/pre-wrap-align-right-003.html
white-space/pre-wrap-align-start-001.html
white-space/pre-wrap-align-start-002.html
white-space/pre-wrap-align-start-003.html
white-space/white-space-pre-wrap-justify-001.html
white-space/white-space-pre-wrap-justify-002.html
white-space/white-space-pre-wrap-justify-003.html
white-space/white-space-pre-wrap-justify-004.html
white-space/eol-spaces-bidi-004.html
Note: [=Hanging=] the white space rather than collapsing it
allows users to see the space when selecting or editing text.
If 'white-space-collapse' is set to ''break-spaces'',
[=spaces=], [=tabs=], and [=other space separators=]
are treated the same as other visible characters:
they cannot [=hang=] nor have their advance width collapsed.
white-space/break-spaces-001.html
white-space/break-spaces-005.html
white-space/textarea-break-spaces-001.html
white-space/break-spaces-tab-005.html
white-space/break-spaces-tab-006.html
white-space/trailing-other-space-separators-break-spaces-001.html
white-space/trailing-other-space-separators-break-spaces-002.html
white-space/trailing-other-space-separators-break-spaces-003.html
white-space/trailing-other-space-separators-break-spaces-004.html
white-space/trailing-other-space-separators-break-spaces-005.html
white-space/trailing-other-space-separators-break-spaces-006.html
white-space/trailing-other-space-separators-break-spaces-007.html
white-space/trailing-other-space-separators-break-spaces-008.html
white-space/trailing-other-space-separators-break-spaces-009.html
white-space/trailing-other-space-separators-break-spaces-010.html
white-space/trailing-other-space-separators-break-spaces-011.html
white-space/trailing-other-space-separators-break-spaces-012.html
white-space/trailing-other-space-separators-break-spaces-013.html
white-space/trailing-other-space-separators-break-spaces-014.html
white-space/trailing-other-space-separators-break-spaces-015.html
line-break/line-break-anywhere-and-white-space-008.html
line-break/line-break-anywhere-and-white-space-009.html
white-space/break-spaces-with-ideographic-space-001.html
white-space/break-spaces-with-ideographic-space-001.html
white-space/break-spaces-with-ideographic-space-005.html
white-space/break-spaces-with-ideographic-space-007.html
white-space/break-spaces-with-ideographic-space-008.html
white-space/break-spaces-with-ideographic-space-009.html
white-space/break-spaces-with-ideographic-space-010.html
white-space/trailing-ideographic-space-break-spaces-001.html
white-space/trailing-ideographic-space-break-spaces-002.html
white-space/trailing-ideographic-space-break-spaces-003.html
white-space/trailing-ideographic-space-break-spaces-004.html
white-space/trailing-ideographic-space-break-spaces-005.html
white-space/trailing-ideographic-space-break-spaces-006.html
white-space/trailing-ideographic-space-break-spaces-007.html
white-space/trailing-ideographic-space-break-spaces-008.html
white-space/trailing-space-and-text-alignment-004.html
white-space/trailing-space-and-text-alignment-rtl-004.html
Note: Such characters therefore take up space,
and depending on the available space
and applicable line breaking controls
will either overflow or cause the line to wrap.
ISSUE: What should happen here for ''white-space-collapse: preserve-spaces''?
This example shows that [=conditionally hanging=] white space
at the end of lines with forced breaks
provides symmetry with the start of the line.
An underline is added to help visualize the spaces.
<p> 0 </p>
The sample above would be rendered as follows:
0
Since the final [=space=] is before a forced line break
and does not overflow,
it does not hang,
and centering works as expected.
This example illustrates the difference
between [=hanging=] [=spaces=]
at the end of lines without forced breaks,
and [=conditionally hanging=] them at the end of lines with forced breaks.
An underline is added to help visualize the [=spaces=].
<p> 0 0 0 0 </p>
The sample above would be rendered as follows:
0 0 0 0
If p { text-align: right; } was added,
the result would be as follows:
0 0 0 0
As the [=preserved=] [=spaces=] at the end of lines without a forced break must [=hang=],
they are not considered when placing the rest of the line during text alignment.
When aligning towards the end,
this means any such [=spaces=] will overflow,
and will not prevent the rest of the line’s content from being flush with the edge of the line.
On the other hand,
preserved spaces at the end of a line with a forced break
[=conditionally hang=].
Since the space at the end of the last line would not overflow in this example,
it does not [=hang=]
and therefore is considered during text alignment.
In the following example,
there is not enough room on any line to fit the end-of-line spaces,
so they [=hang=] on all lines:
the one on the line without a forced break because it must,
as well as the one on the line with a forced break,
because it [=conditionally hangs=] and overflows.
An underline is added to help visualize the spaces.
The last line is not wrapped before the last 0
because characters that [=conditionally hang=] are not considered
when measuring the line’s contents for fit.
Segment Break Transformation Rules
When 'white-space-collapse' is not ''white-space-collapse/collapse'',
[=segment breaks=] are not [=collapsible=].
For values other than ''white-space-collapse/collapse''
or ''white-space-collapse/preserve-spaces''
(which transforms them into [=spaces=]),
[=segment breaks=] are instead transformed into a preserved line feed (U+000A).
white-space-008.xht
white-space-processing-016.xht
white-space-processing-017.xht
white-space-processing-018.xht
When 'white-space-collapse' is ''white-space-collapse/collapse'',
[=segment breaks=] are [=collapsible=],
and are collapsed as follows:
First, any collapsible [=segment break=]
immediately following another collapsible [=segment break=]
is removed.
line-breaking/segment-break-transformation-unremovable-2.html
line-breaking/segment-break-transformation-unremovable-4.html
Then any remaining [=segment break=]
is either transformed into a space (U+0020)
or removed
depending on the context before and after the break.
The rules for this operation are UA-defined in this level.
line-breaking/segment-break-transformation-unremovable-1.html
line-breaking/segment-break-transformation-unremovable-2.html
line-breaking/segment-break-transformation-unremovable-3.html
line-breaking/segment-break-transformation-unremovable-4.html
ISSUE: Should we define this for Level 4?
white-space/seg-break-transformation-000.tentative.html
white-space/seg-break-transformation-001.tentative.html
white-space/seg-break-transformation-002.tentative.html
white-space/seg-break-transformation-003.tentative.html
white-space/seg-break-transformation-004.tentative.html
white-space/seg-break-transformation-005.tentative.html
white-space/seg-break-transformation-006.tentative.html
white-space/seg-break-transformation-007.tentative.html
white-space/seg-break-transformation-008.tentative.html
white-space/seg-break-transformation-009.tentative.html
white-space/seg-break-transformation-010.tentative.html
white-space/seg-break-transformation-011.tentative.html
white-space/seg-break-transformation-012.tentative.html
white-space/seg-break-transformation-014.tentative.html
white-space/seg-break-transformation-015.tentative.html
white-space/seg-break-transformation-016.tentative.html
white-space/seg-break-transformation-017.tentative.html
white-space/seg-break-transformation-018.tentative.html
white-space/seg-break-transformation-019.tentative.html
line-breaking/segment-break-transformation-removable-1.html
line-breaking/segment-break-transformation-removable-2.html
line-breaking/segment-break-transformation-removable-3.html
line-breaking/segment-break-transformation-removable-4.html
line-breaking/segment-break-transformation-rules-001.html
line-breaking/segment-break-transformation-rules-002.html
line-breaking/segment-break-transformation-rules-003.html
line-breaking/segment-break-transformation-rules-004.html
line-breaking/segment-break-transformation-rules-005.html
line-breaking/segment-break-transformation-rules-006.html
line-breaking/segment-break-transformation-rules-007.html
line-breaking/segment-break-transformation-rules-008.html
line-breaking/segment-break-transformation-rules-009.html
line-breaking/segment-break-transformation-rules-010.html
line-breaking/segment-break-transformation-rules-011.html
line-breaking/segment-break-transformation-rules-012.html
line-breaking/segment-break-transformation-rules-013.html
line-breaking/segment-break-transformation-rules-014.html
line-breaking/segment-break-transformation-rules-015.html
line-breaking/segment-break-transformation-rules-016.html
line-breaking/segment-break-transformation-rules-017.html
line-breaking/segment-break-transformation-rules-018.html
line-breaking/segment-break-transformation-rules-019.html
line-breaking/segment-break-transformation-rules-020.html
line-breaking/segment-break-transformation-rules-021.html
line-breaking/segment-break-transformation-rules-022.html
line-breaking/segment-break-transformation-rules-023.html
line-breaking/segment-break-transformation-rules-024.html
line-breaking/segment-break-transformation-rules-025.html
line-breaking/segment-break-transformation-rules-026.html
line-breaking/segment-break-transformation-rules-027.html
line-breaking/segment-break-transformation-rules-028.html
line-breaking/segment-break-transformation-rules-029.html
line-breaking/segment-break-transformation-rules-030.html
line-breaking/segment-break-transformation-rules-031.html
line-breaking/segment-break-transformation-rules-032.html
line-breaking/segment-break-transformation-rules-033.html
line-breaking/segment-break-transformation-rules-034.html
line-breaking/segment-break-transformation-rules-035.html
line-breaking/segment-break-transformation-rules-036.html
line-breaking/segment-break-transformation-rules-037.html
line-breaking/segment-break-transformation-rules-038.html
line-breaking/segment-break-transformation-rules-039.html
line-breaking/segment-break-transformation-rules-040.html
line-breaking/segment-break-transformation-rules-041.html
line-breaking/segment-break-transformation-rules-042.html
line-breaking/segment-break-transformation-rules-043.html
line-breaking/segment-break-transformation-rules-044.html
line-breaking/segment-break-transformation-rules-045.html
line-breaking/segment-break-transformation-rules-046.html
line-breaking/segment-break-transformation-rules-047.html
line-breaking/segment-break-transformation-rules-048.html
line-breaking/segment-break-transformation-rules-049.html
Note: The white space processing rules have already
removed any [=tabs=] and [=spaces=] around the [=segment break=]
before this context is evaluated.
The purpose of the segment break transformation rules
(and white space collapsing in general)
is to “unbreak” text that has been
[[#white-space-processing|broken into segments]]
to make the document source code easier to work with.
In languages that use word separators, such as English and Korean,
“unbreaking” a line requires joining the two lines with a [=space=].
Here is an English paragraph
that is broken into multiple lines
in the source code so that it can
be more easily read and edited
in a text editor.
Here is an English paragraph that is broken into multiple lines in the source code so that it can be more easily read and edited in a text editor.
Eliminating a line break in English
requires maintaining a [=space=] in its place.
In languages that have no word separators, such as Chinese,
“unbreaking” a line requires joining the two lines with no intervening space.
這個段落是那麼長，
在一行寫不行。最好
用三行寫。
這個段落是那麼長，在一行寫不行。最好用三行寫。
Eliminating a line break in Chinese
requires eliminating any intervening [=white space=].
The segment break transformation rules can use adjacent context
to either transform the segment break into a space
or eliminate it entirely.
Note: Historically, HTML and CSS have unconditionally converted [=segment breaks=] to spaces,
which has prevented content authored in languages such as Chinese
from being able to break lines within the source.
Thus UA heuristics need to be conservative about where they discard [=segment breaks=]
even as they strive to improve support for such languages.
Tab Character Size: the 'tab-size' property
Name: tab-size
Value: <> | <>
Initial: 8
Applies to: text
Inherited: yes
Computed value: the specified number or absolute length
Animation type: by computed value type
Canonical order: n/a
tab-size/tab-size-integer-001.html
tab-size/tab-size.html
tab-size/tab-size-inheritance-001.html
inheritance.html
parsing/tab-size-valid.html
parsing/tab-size-invalid.html
parsing/tab-size-computed.html
tab-size/tab-size-computed-value-001.html
tab-size/tab-size-inline-001.html
animations/tab-size-interpolation.html
This property determines the tab size
used to render [=preserved=] tab characters (U+0009).
A <> represents the measure
as a multiple of the advance width of the space character (U+0020)
of the nearest [=block container=] ancestor of the [=preserved=] [=tab=],
including its associated 'letter-spacing' and 'word-spacing'.
Negative values are not allowed.
tab-size/tab-size-integer-001.html
tab-size/tab-size-integer-002.html
tab-size/tab-size-integer-003.html
tab-size/tab-size-integer-004.html
tab-size/tab-size-integer-005.html
tab-size/tab-size-length-001.html
tab-size/tab-size-length-002.html
tab-size/tab-size-percent-001.html
tab-size/tab-min-rendered-width-1.html
tab-size/tab-size-spacing-001.html
tab-size/tab-size-spacing-002.html
tab-size/tab-size-spacing-003.html
white-space/tab-stop-threshold-001.html
white-space/tab-stop-threshold-002.html
white-space/tab-stop-threshold-003.html
white-space/tab-stop-threshold-004.html
white-space/tab-stop-threshold-005.html
white-space/tab-stop-threshold-006.html
text-indent/text-indent-tab-positions-001.html
tab-size/tab-size-block-ancestor.html
white-space-processing-042.xht
Text Wrapping
When inline-level content is laid out into lines, it is broken across line boxes.
Such a break is called a line break.
When a line is broken due to explicit line-breaking controls
(such as a preserved newline character),
or due to the start or end of a block,
it is a forced line break.
When a line is broken due to content wrapping
(i.e. when the UA creates unforced line breaks
in order to fit the content within the measure),
it is a soft wrap break.
The process of breaking inline-level content into lines is called line breaking.
Wrapping is only performed at an allowed break point,
called a soft wrap opportunity.
When wrapping is enabled (see 'white-space'),
the UA must minimize the amount of content overflowing a line
by wrapping the line at a [=soft wrap opportunity=],
if one exists.
line-breaking/line-breaking-020.html
Where text is allowed to wrap is controlled
by the [[#line-breaking|line-breaking rules and controls]];
whether it is allowed to wrap
and how multiple [=soft wrap opportunities=] within a line are prioritized
is controlled
by the 'text-wrap-mode',
'text-wrap-style',
'wrap-before',
'wrap-after',
and
'wrap-inside' properties.
Deciding Whether to Wrap: the 'text-wrap-mode' property
parsing/text-wrap-mode-computed.html
parsing/text-wrap-mode-invalid.html
parsing/text-wrap-mode-valid.html
Issue: The name of this property is a placeholder,
pending the CSSWG finding a better name.
Note: This property is a [=longhand=]
of both 'white-space' and 'text-wrap'.
This property specifies whether lines may [=wrap=] at unforced [=soft wrap opportunities=].
Possible values:
Regardless of the 'text-wrap-mode' value,
[=preserved=] [=segment breaks=],
and any Unicode character with the BK, CR, LF, and NL line breaking class,
must be treated as [=forced line breaks=].
[[!UAX14]]
line-breaking/line-breaking-022.html
Note: The bidi implications of such [=forced line breaks=]
are defined by the Unicode Bidirectional Algorithm.
[[!UAX9]]
Controlling Breaks Within Boxes: the 'wrap-inside' property
Name: wrap-inside
Value: auto | avoid
Initial: auto
Applies to: inline boxes
Inherited: no
Percentages: n/a
Computed value: specified keyword
Animation type: discrete
auto
Lines may break at allowed break points
within the box,
as determined by the line-breaking rules in effect.
avoid
Line breaking is suppressed within the box:
the UA may only break within the box
if there are no other valid break points in the line.
If the text breaks,
line-breaking restrictions are honored as for
''wrap-inside/auto''.
If boxes with ''wrap-inside/avoid'' are nested
and the UA must break within these boxes,
a break in an outer box must be used
before a break within an inner box may be used.
Example of using 'wrap-inside: avoid' in presenting a footer
The priority of breakpoints can be set
to reflect the intended grouping of text.
Given the rules
footer { wrap-inside: avoid; }
venue { wrap-inside: avoid; }
date { wrap-inside: avoid; }
place { wrap-inside: avoid; }
27th Internationalization and Unicode Conference •
April 7, 2005 • Berlin, Germany
or in a narrower window as
27th Internationalization and Unicode
Conference • April 7, 2005 •
Berlin, Germany
but not as
27th Internationalization and Unicode Conference • April
7, 2005 • Berlin, Germany
Controlling Breaks Between Boxes: the 'wrap-before'/'wrap-after' properties
Name: wrap-before, wrap-after
Value: auto | avoid | avoid-line | avoid-flex | line | flex
Initial: auto
Applies to: inline-level boxes and flex items
Inherited: no
Percentages: n/a
Computed value: specified keyword
Animation type: discrete
These properties specify modifications to break opportunities
in line breaking (and flex line breaking [[CSS3-FLEXBOX]]).
Possible values:
auto
Lines may break at allowed break points
before and after the box,
as determined by the line-breaking rules in effect.
avoid
Line breaking is suppressed immediately before/after the box:
the UA may only break there
if there are no other valid break points
in the line.
If the text breaks,
line-breaking restrictions are honored as for
''wrap-before/auto''.
avoid-line
Same as ''wrap-before/avoid'',
but only for line breaks.
avoid-flex
Same as ''wrap-before/avoid'',
but only for flex line breaks.
line
Force a line break immediately before/after the box
if the box is an inline-level box.
Selecting How to Wrap: the 'text-wrap-style' property
Name: text-wrap-style
Value: auto | balance | stable | pretty | avoid-orphans
Initial: auto
Applies to: [=block containers=] hat establish an [=inline formatting context=]
Inherited: yes
Percentages: n/a
Computed value: specified keyword
Animation type: discrete
Issue: The CSSWG is looking for a better name for ''avoid-orphans''.
parsing/text-wrap-style-computed.html
parsing/text-wrap-style-invalid.html
parsing/text-wrap-style-valid.html
parsing/text-wrap-pretty.html
white-space/text-wrap-balance-before-after-002.html
When wrapping is allowed
(see 'text-wrap-mode'),
this property selects between several approaches for wrapping lines,
trading off between speed, quality and style of layout, or stability.
It does not change which [=soft wrap opportunity=] exist,
but changes how the user agent selects among them.
Possible values:
auto
The exact algorithm for selecting
which [=soft wrap opportunity=] to break at is UA-defined.
The algorithm may consider multiple lines
when making break decisions.
The UA may bias for speed over best layout.
The UA must not attempt to even out all lines
(including the last) as for ''text-wrap-style/balance''.
This value selects the UA’s preferred (or most Web-compatible)
wrapping algorithm.
balance
Line breaks are chosen to balance
the remaining (empty) space in each line box,
if better balance than ''text-wrap-style/auto'' is possible.
This should avoid changing--
and in the case of 5 or fewer lines must not change--
the number of line boxes
the block would contain
if 'text-wrap' were set to ''text-wrap-style/auto''.
Note: The height of the line boxes may nevertheless change,
due to changes in which content appears together on one line.
white-space/text-wrap-balance-001.html
white-space/text-wrap-balance-002.html
white-space/text-wrap-balance-003.html
white-space/text-wrap-balance-align-001.html
white-space/text-wrap-balance-dynamic-001.html
white-space/text-wrap-balance-line-clamp-001.html
white-space/text-wrap-balance-narrow-crash.html
crashtests/text-wrap-balance-float-crash.html
crashtests/text-wrap-balance-nested-blocks-crash.html
white-space/text-wrap-balance-overflow-001.html
white-space/text-wrap-balance-overflow-002.html
white-space/text-wrap-balance-right-to-left.html
white-space/text-wrap-balance-top-to-bottom.html
white-space/text-wrap-balance-before-after-001.html
The remaining space to consider
is that which remains after placing floats and inline content,
but before any adjustments due to text justification.
Line boxes are balanced when the standard deviation
from the average inline-size of the remaining space in each line box
is reduced over the block
(including lines that end in a forced break).
white-space/text-wrap-balance-text-indent-001.html
white-space/text-wrap-balance-float-001.html
white-space/text-wrap-balance-float-002.html
white-space/text-wrap-balance-float-003.html
white-space/text-wrap-balance-float-004.html
white-space/text-wrap-balance-float-005.html
white-space/text-wrap-balance-float-006.html
Groups of lines separated by a [=forced line break=]
are processed separately.
If the element is affected by 'line-clamp',
the clamping effect is applied first,
then the remaining lines are balanced.
white-space/text-wrap-balance-004.html
white-space/text-wrap-balance-005.html
The exact algorithm is UA-defined.
UAs may treat this value as ''text-wrap-style/auto'' if there are more than ten lines to balance.
stable
Specifies that content on subsequent lines
should not be considered when making break decisions
so that when editing text any content before the cursor
remains stable;
otherwise equivalent to ''text-wrap-style/auto'',
pretty
Specifies the UA should bias for better layout over speed,
and is expected to consider multiple lines
when making break decisions.
Otherwise equivalent to ''text-wrap-style/auto''.
The user agent may among other things
attempt to avoid excessively short last lines,
similarly to ''avoid-orphans'',
but it should also improve the layout in additional ways.
The precise set of improvements is user agent dependent,
and may include things such as:
reducing the variation in length between lines;
avoiding typographic rivers;
prioritizing different classes of [=soft wrap opportunities=], [=hyphenation opportunities=], or [=justification opportunities=];
avoiding hyphenation on too many consecutive lines…
The necessary computations may be expensive,
especially when applied to large amounts of text.
Authors are encouraged to assess the impact on performance
when using ''text-wrap-style: pretty'',
and possibly use it selectively where it matters most.
avoid-orphans
Specifies the UA should avoid excessively short last lines,
and is expected to consider more than one line
when making break decisions
(for example, to avoid "fixing" an orphan
by making the previous line too short).
The user agent may decide against improving the last line
when it would make some prior line(s) substantially unbalanced.
The user agent should not attempt to improve other aspects of the layout
beyond what ''text-wrap-style/auto''
if those improvements come at a significant performance cost.
Note: In western typography, an “orphan” can refer to a single word on the last line of a paragraph.
However, not all languages or writing systems wrap lines at word boundaries,
and even in languages that do,
a few very short words on the last line may still be undesirable,
especially if the available inline space is long.
This specification does not therefore strictly define
lines to be too short only when they are composed a single word,
and lets the user agent be the judge of what is excessively short.
Note: See also the 'orphans' property for control over fragmentation
and the other typographic meaning of “orphans”.
For instance, with the given line length, the following test would be wrapped with a single word on the last line,
which could be judged too short.
An attempt to make the last line less short by wrapping the previous line earlier would result in the following:
Circumnavigating
the
Mississippi river
While the last line would indeed no longer be short,
the penultimate line would be unsightly.
In such cases, user agents are expected
to prefer the first rendering
despite ''text-wrap-style: avoid-orphans'' being set.
Note: The ''text-wrap-style/auto'' value will typically map
to Web browsers’ speedy legacy line breaking,
which has so far used first-fit/greedy algorithms
that can often give sub-optimal results.
UAs can experiment with better line breaking algorithms
with this default value,
but as optimal results often take more time,
''text-wrap-style/pretty'' and ''avoid-orphans'' are offered as opt-ins
to take more time for better results.
Both values are intended for body text,
where the last line is expected to be a bit shorter than the average line,
but ''avoid-orphans'' aims to avoid excessively short last lines while staying performant,
while ''pretty'' can sacrifice more speed in pursuit of even better layout;
the ''text-wrap-style/balance'' value is intended for titles and captions,
where equal-length lines of text tend to be preferred;
and the ''text-wrap-style/stable'' is intended for sections that are,
or are likely become toggled as,
editable.
See thread.
Issue is about requiring a minimum length for lines.
Common measures seem to be
At least as long as the text-indent.
At least X characters.
Percentage-based.
Suggestion for value space is ''match-indent | <> | <>''
(with ''Xch'' given as an example to make that use case clear).
Alternately <> could actually count the characters.
It's unclear how this would interact with text balancing (above);
one earlier proposal had them be the same property
(with ''100%'' meaning full balancing).
People have requested word-based limits, but since this is really
dependent on the length of the word, character-based is better.
Joint Wrapping Control: the 'text-wrap' shorthand property
Name: text-wrap
Value: <<'text-wrap-mode'>> || <<'text-wrap-style'>>
Initial: wrap
Applies to: see individual properties
Inherited: see individual properties
Percentages: see individual properties
Computed value: see individual properties
Animation type: see individual properties
parsing/text-wrap-invalid.html
parsing/text-wrap-valid.html
parsing/text-wrap-computed.html
parsing/text-wrap-pretty.html
parsing/white-space-shorthand-text-wrap.html
This property is a shorthand for the 'text-wrap-mode' and 'text-wrap-style' properties.
Any omitted [=longhand=] is set to its [=initial value=].
Line Breaking Details
When determining [=line breaks=]:
The interaction of [=line breaking=] and bidirectional text is defined by
[[css-writing-modes-4#bidi-algo]]
and the Unicode Bidirectional Algorithm
(UAX9§3.4 Reordering Resolved Levels in particular).
[[!CSS-WRITING-MODES-4]]
[[!UAX9]]
bidi-breaking-001.xht
bidi-breaking-002.xht
bidi-breaking-003.xht
Except where explicitly defined otherwise
(e.g. for ''line-break: anywhere'' or ''overflow-wrap: anywhere'')
line breaking behavior defined for
the CM,
and SG,
WJ,
ZW,
GL,
and ZWJ
Unicode line breaking classes
must be honored.
[[!UAX14]]
word-break/word-break-normal-001.html
line-breaking/line-breaking-001.html
line-breaking/line-breaking-002.html
line-breaking/line-breaking-003.html
line-breaking/line-breaking-004.html
line-breaking/line-breaking-005.html
line-breaking/line-breaking-006.html
line-breaking/line-breaking-007.html
line-breaking/line-breaking-008.html
line-breaking/line-breaking-021.html
i18n/css3-text-line-break-baspglwj-001.html
i18n/css3-text-line-break-baspglwj-002.html
i18n/css3-text-line-break-baspglwj-120.html
i18n/css3-text-line-break-baspglwj-121.html
i18n/css3-text-line-break-baspglwj-122.html
i18n/css3-text-line-break-baspglwj-123.html
i18n/css3-text-line-break-baspglwj-124.html
i18n/css3-text-line-break-baspglwj-125.html
i18n/css3-text-line-break-baspglwj-126.html
i18n/css3-text-line-break-baspglwj-127.html
i18n/css3-text-line-break-baspglwj-128.html
i18n/css3-text-line-break-baspglwj-130.html
i18n/css3-text-line-break-baspglwj-131.html
word-break/word-break-break-all-018.html
word-break/word-break-break-all-021.html
word-break/word-break-break-all-022.html
UAs that allow wrapping at punctuation
other than [=word separators=]
in writing systems that use them
should prioritize breakpoints.
(For example, if breaks after slashes are given a lower priority than spaces,
the sequence “check /etc” will never break between the "/" and the "e".)
As long as care is taken to avoid such awkward breaks,
allowing breaks at appropriate punctuation other than [=word separators=]
is recommended,
as it results in more even-looking margins, particularly in narrow measures.
The UA may use the width of the containing block, the text's language,
the 'line-break' value,
and other factors in assigning priorities:
CSS does not define prioritization of [=soft wrap opportunities=].
Prioritization of [=word separators=] is not expected,
however,
if ''word-break: break-all'' is specified
(since this value explicitly requests line breaking behavior
not based on breaking at [=word separators=])--
and is forbidden under ''line-break: anywhere''.
Out-of-flow elements
and inline element boundaries
do not introduce a [=forced line break=]
or [=soft wrap opportunity=] in the flow.
line-breaking/line-breaking-012.html
line-breaking/line-breaking-015.html
line-breaking/line-breaking-016.html
line-breaking/line-breaking-017.html
line-breaking/line-breaking-018.html
line-breaking/line-breaking-019.html
For Web-compatibility
there is a [=soft wrap opportunity=]
before and after each replaced element or other [=atomic inline=],
even when adjacent to a character that would normally suppress them,
including U+00A0 NO-BREAK SPACE.
However,
with the exception of U+00A0 NO-BREAK SPACE,
there must be no [=soft wrap opportunity=]
between [=atomic inlines=] and adjacent characters
belonging to the Unicode GL, WJ, or ZWJ line breaking classes.
[[UAX14]]
line-breaking/line-breaking-atomic-001.html
line-breaking/line-breaking-atomic-002.html
line-breaking/line-breaking-atomic-003.html
line-breaking/line-breaking-atomic-004.html
line-breaking/line-breaking-atomic-005.html
line-breaking/line-breaking-atomic-006.html
line-breaking/line-breaking-atomic-007.html
line-breaking/line-breaking-atomic-008.html
line-breaking/line-breaking-atomic-009.html
line-breaking/line-breaking-atomic-010.html
line-breaking/line-breaking-atomic-011.html
line-breaking/line-breaking-atomic-012.html
line-breaking/line-breaking-atomic-013.html
line-breaking/line-breaking-atomic-014.html
line-breaking/line-breaking-atomic-015.html
line-breaking/line-breaking-atomic-016.html
line-breaking/line-breaking-atomic-017.html
line-breaking/line-breaking-atomic-018.html
line-breaking/line-breaking-atomic-019.html
line-breaking/line-breaking-atomic-020.html
line-breaking/line-breaking-atomic-021.html
line-breaking/line-breaking-atomic-022.html
line-breaking/line-breaking-atomic-023.html
line-breaking/line-breaking-atomic-024.html
line-breaking/line-breaking-atomic-025.html
line-breaking/line-breaking-atomic-026.html
line-breaking/line-breaking-atomic-027.html
line-breaking/line-breaking-replaced-001.html
line-breaking/line-breaking-replaced-002.html
line-breaking/line-breaking-replaced-003.html
line-breaking/line-breaking-replaced-004.html
line-breaking/line-breaking-replaced-005.html
line-breaking/line-breaking-replaced-006.html
line-breaking/line-breaking-atomic-nowrap-001.html
For [=soft wrap opportunities=] created by characters
that disappear at the line break (e.g. U+0020 SPACE),
properties on the box directly containing that character
control the line breaking at that opportunity.
For [=soft wrap opportunities=] defined by the boundary between two characters or [=atomic inlines=],
the 'white-space' property
on the nearest common ancestor of the two characters
controls breaking;
which elements’ 'line-break', 'word-break', and 'overflow-wrap' properties
control the determination of [=soft wrap opportunities=]
at such boundaries
is undefined in this level.
line-breaking/line-breaking-009.html
line-breaking/line-breaking-010.html
line-breaking/line-breaking-011.html
line-breaking/line-breaking-ic-001.html
line-breaking/line-breaking-ic-002.html
line-breaking/line-breaking-ic-003.html
white-space/white-space-wrap-after-nowrap-001.html
word-break/break-boundary-2-chars-001.html
overflow-wrap/overflow-wrap-anywhere-inline-002.tentative.html
overflow-wrap/overflow-wrap-anywhere-inline-003.tentative.html
overflow-wrap/overflow-wrap-anywhere-inline-004.tentative.html
word-break/word-break-break-all-inline-004.tentative.html
word-break/word-break-break-all-inline-007.tentative.html
word-break/word-break-break-all-inline-010.tentative.html
line-breaking/line-breaking-030.html
line-breaking/line-breaking-031.html
line-breaking/line-breaking-032.html
For [=soft wrap opportunities=] before the first
or after the last character of a box,
the break occurs immediately before/after the box
(at its margin edge)
rather than breaking the box
between its content edge and the content.
Line breaking in/around Ruby is defined
in [[css-ruby-1#line-breaks]].
[[!CSS-RUBY-1]]
When shaping scripts such as Arabic
[=wrap=] at unforced [=soft wrap opportunities=] within words
(such as when breaking due to
''word-break: break-all'',
''line-break: anywhere'',
''overflow-wrap: break-word'',
''overflow-wrap: anywhere'',
or when [=hyphenating=])
the characters must still be shaped
(their joining forms chosen)
as if the word were still whole.
hyphens/hyphens-shaping-001.html
hyphens/hyphens-shaping-002.html
line-break/line-break-shaping-001.html
overflow-wrap/overflow-wrap-shaping-001.html
overflow-wrap/overflow-wrap-shaping-002.html
word-break/word-break-break-all-004.html
For example,
if the word “نوشتن” is broken between the “ش” and “ت”,
the “ش” still takes its initial form (“ﺷ”),
and the “ت” its medial form (“ﺘ”)--
forming as in “ﻧﻮﺷ | ﺘﻦ”, not as in “نوش | تن”.
Line Breaking and Word Boundaries
In most writing systems,
in the absence of hyphenation a [=soft wrap opportunity=] occurs only at word boundaries.
Many such systems use [=spaces=] or punctuation to explicitly separate words,
and [=soft wrap opportunities=] can be identified by these characters.
i18n/css3-text-line-break-baspglwj-003.html
i18n/css3-text-line-break-baspglwj-004.html
i18n/css3-text-line-break-baspglwj-005.html
i18n/css3-text-line-break-baspglwj-006.html
i18n/css3-text-line-break-baspglwj-007.html
i18n/css3-text-line-break-baspglwj-008.html
i18n/css3-text-line-break-baspglwj-009.html
i18n/css3-text-line-break-baspglwj-010.html
i18n/css3-text-line-break-baspglwj-011.html
i18n/css3-text-line-break-baspglwj-012.html
i18n/css3-text-line-break-baspglwj-014.html
i18n/css3-text-line-break-baspglwj-015.html
i18n/css3-text-line-break-baspglwj-016.html
i18n/css3-text-line-break-baspglwj-017.html
i18n/css3-text-line-break-baspglwj-018.html
i18n/css3-text-line-break-baspglwj-019.html
i18n/css3-text-line-break-baspglwj-020.html
i18n/css3-text-line-break-baspglwj-021.html
i18n/css3-text-line-break-baspglwj-022.html
i18n/css3-text-line-break-baspglwj-023.html
i18n/css3-text-line-break-baspglwj-024.html
i18n/css3-text-line-break-baspglwj-025.html
i18n/css3-text-line-break-baspglwj-026.html
i18n/css3-text-line-break-baspglwj-030.html
i18n/css3-text-line-break-baspglwj-031.html
i18n/css3-text-line-break-baspglwj-032.html
i18n/css3-text-line-break-baspglwj-033.html
i18n/css3-text-line-break-baspglwj-034.html
i18n/css3-text-line-break-baspglwj-035.html
i18n/css3-text-line-break-baspglwj-036.html
i18n/css3-text-line-break-baspglwj-037.html
i18n/css3-text-line-break-baspglwj-038.html
i18n/css3-text-line-break-baspglwj-039.html
i18n/css3-text-line-break-baspglwj-040.html
i18n/css3-text-line-break-baspglwj-041.html
i18n/css3-text-line-break-baspglwj-042.html
i18n/css3-text-line-break-baspglwj-043.html
i18n/css3-text-line-break-baspglwj-044.html
i18n/css3-text-line-break-baspglwj-045.html
i18n/css3-text-line-break-baspglwj-046.html
i18n/css3-text-line-break-baspglwj-047.html
i18n/css3-text-line-break-baspglwj-048.html
i18n/css3-text-line-break-baspglwj-049.html
i18n/css3-text-line-break-baspglwj-050.html
i18n/css3-text-line-break-baspglwj-051.html
i18n/css3-text-line-break-baspglwj-052.html
i18n/css3-text-line-break-baspglwj-060.html
i18n/css3-text-line-break-baspglwj-061.html
i18n/css3-text-line-break-baspglwj-062.html
i18n/css3-text-line-break-baspglwj-063.html
i18n/css3-text-line-break-baspglwj-064.html
i18n/css3-text-line-break-baspglwj-065.html
i18n/css3-text-line-break-baspglwj-066.html
i18n/css3-text-line-break-baspglwj-067.html
i18n/css3-text-line-break-baspglwj-068.html
i18n/css3-text-line-break-baspglwj-069.html
i18n/css3-text-line-break-baspglwj-070.html
i18n/css3-text-line-break-baspglwj-071.html
i18n/css3-text-line-break-baspglwj-072.html
i18n/css3-text-line-break-baspglwj-073.html
i18n/css3-text-line-break-baspglwj-074.html
i18n/css3-text-line-break-baspglwj-075.html
i18n/css3-text-line-break-baspglwj-076.html
i18n/css3-text-line-break-baspglwj-077.html
i18n/css3-text-line-break-baspglwj-078.html
i18n/css3-text-line-break-baspglwj-080.html
i18n/css3-text-line-break-baspglwj-081.html
i18n/css3-text-line-break-baspglwj-082.html
i18n/css3-text-line-break-baspglwj-083.html
i18n/css3-text-line-break-baspglwj-084.html
i18n/css3-text-line-break-baspglwj-085.html
i18n/css3-text-line-break-baspglwj-086.html
i18n/css3-text-line-break-baspglwj-090.html
i18n/css3-text-line-break-baspglwj-091.html
i18n/css3-text-line-break-baspglwj-092.html
i18n/css3-text-line-break-baspglwj-093.html
i18n/css3-text-line-break-baspglwj-095.html
i18n/css3-text-line-break-baspglwj-096.html
i18n/css3-text-line-break-baspglwj-097.html
i18n/css3-text-line-break-baspglwj-098.html
i18n/css3-text-line-break-baspglwj-099.html
i18n/css3-text-line-break-baspglwj-100.html
i18n/css3-text-line-break-baspglwj-101.html
i18n/css3-text-line-break-baspglwj-102.html
i18n/css3-text-line-break-baspglwj-103.html
i18n/css3-text-line-break-baspglwj-104.html
i18n/css3-text-line-break-baspglwj-105.html
i18n/css3-text-line-break-baspglwj-106.html
i18n/css3-text-line-break-baspglwj-107.html
i18n/css3-text-line-break-baspglwj-108.html
i18n/css3-text-line-break-baspglwj-109.html
i18n/css3-text-line-break-baspglwj-110.html
i18n/css3-text-line-break-baspglwj-111.html
i18n/css3-text-line-break-baspglwj-112.html
i18n/css3-text-line-break-baspglwj-113.html
i18n/css3-text-line-break-baspglwj-114.html
i18n/css3-text-line-break-baspglwj-115.html
i18n/css3-text-line-break-baspglwj-116.html
i18n/css3-text-line-break-baspglwj-117.html
i18n/css3-text-line-break-baspglwj-118.html
word-break/word-break-normal-bo-000.html
word-break/word-break-normal-en-000.html
word-break/word-break-normal-ethiopic.html
word-break/word-break-normal-hi-000.html
word-break/word-break-normal-ko-000.html
Scripts such as Thai, Lao, and Khmer, however,
do not use spaces or punctuation to separate words.
Although the zero width space (U+200B) can be used as an explicit word delimiter
in these scripts,
this practice is not common.
As a result, a lexical resource is needed
to correctly identify [=soft wrap opportunities=] in such texts.
word-break/word-break-normal-002.html
word-break/word-break-normal-003.html
word-break/word-break-normal-th-000.html
word-break/word-break-normal-th-001.html
word-break/word-break-normal-km-000.html
word-break/word-break-normal-lo-000.html
word-break/word-break-normal-my-000.html
word-break/word-break-normal-tdd-000.html
In some other writing systems,
[=soft wrap opportunities=] are based on orthographic syllable boundaries,
not word boundaries.
Some of these systems,
notably Brahmic scripts such as Javanese and Balinese,
require analysis of the text to find breaking opportunities.
Unlike languages that use characters from the SA line breaking class,
this analysis does not depend on the [=content language=]
nor requires (language specific) [=word boundary detection=]
or a lexical resource.
In others such as Chinese (as well as Japanese, Yi, and sometimes also Korean),
each syllable tends to correspond to a single [=typographic letter unit=],
and thus line breaking conventions allow the line to break
anywhere except between certain character combinations.
Additionally the level of strictness in these restrictions
varies with the typesetting style.
word-break/word-break-normal-ja-000.html
word-break/word-break-normal-ja-001.html
word-break/word-break-normal-ja-002.html
word-break/word-break-normal-ja-004.html
word-break/word-break-normal-zh-000.html
i18n/css3-text-line-break-opclns-001.html
i18n/css3-text-line-break-opclns-002.html
i18n/css3-text-line-break-opclns-003.html
i18n/css3-text-line-break-opclns-004.html
i18n/css3-text-line-break-opclns-005.html
i18n/css3-text-line-break-opclns-006.html
i18n/css3-text-line-break-opclns-007.html
i18n/css3-text-line-break-opclns-008.html
i18n/css3-text-line-break-opclns-009.html
i18n/css3-text-line-break-opclns-010.html
i18n/css3-text-line-break-opclns-011.html
i18n/css3-text-line-break-opclns-012.html
i18n/css3-text-line-break-opclns-014.html
i18n/css3-text-line-break-opclns-015.html
i18n/css3-text-line-break-opclns-016.html
i18n/css3-text-line-break-opclns-017.html
i18n/css3-text-line-break-opclns-018.html
i18n/css3-text-line-break-opclns-019.html
i18n/css3-text-line-break-opclns-020.html
i18n/css3-text-line-break-opclns-021.html
i18n/css3-text-line-break-opclns-022.html
i18n/css3-text-line-break-opclns-023.html
i18n/css3-text-line-break-opclns-024.html
i18n/css3-text-line-break-opclns-025.html
i18n/css3-text-line-break-opclns-026.html
i18n/css3-text-line-break-opclns-027.html
i18n/css3-text-line-break-opclns-028.html
i18n/css3-text-line-break-opclns-029.html
i18n/css3-text-line-break-opclns-030.html
i18n/css3-text-line-break-opclns-031.html
i18n/css3-text-line-break-opclns-032.html
i18n/css3-text-line-break-opclns-033.html
i18n/css3-text-line-break-opclns-034.html
i18n/css3-text-line-break-opclns-035.html
i18n/css3-text-line-break-opclns-036.html
i18n/css3-text-line-break-opclns-037.html
i18n/css3-text-line-break-opclns-038.html
i18n/css3-text-line-break-opclns-039.html
i18n/css3-text-line-break-opclns-040.html
i18n/css3-text-line-break-opclns-041.html
i18n/css3-text-line-break-opclns-042.html
i18n/css3-text-line-break-opclns-043.html
i18n/css3-text-line-break-opclns-044.html
i18n/css3-text-line-break-opclns-045.html
i18n/css3-text-line-break-opclns-046.html
i18n/css3-text-line-break-opclns-047.html
i18n/css3-text-line-break-opclns-049.html
i18n/css3-text-line-break-opclns-050.html
i18n/css3-text-line-break-opclns-051.html
i18n/css3-text-line-break-opclns-052.html
i18n/css3-text-line-break-opclns-053.html
i18n/css3-text-line-break-opclns-054.html
i18n/css3-text-line-break-opclns-055.html
i18n/css3-text-line-break-opclns-056.html
i18n/css3-text-line-break-opclns-057.html
i18n/css3-text-line-break-opclns-058.html
i18n/css3-text-line-break-opclns-059.html
i18n/css3-text-line-break-opclns-060.html
i18n/css3-text-line-break-opclns-061.html
i18n/css3-text-line-break-opclns-062.html
i18n/css3-text-line-break-opclns-063.html
i18n/css3-text-line-break-opclns-064.html
i18n/css3-text-line-break-opclns-065.html
i18n/css3-text-line-break-opclns-100.html
i18n/css3-text-line-break-opclns-101.html
i18n/css3-text-line-break-opclns-102.html
i18n/css3-text-line-break-opclns-103.html
i18n/css3-text-line-break-opclns-104.html
i18n/css3-text-line-break-opclns-105.html
i18n/css3-text-line-break-opclns-106.html
i18n/css3-text-line-break-opclns-107.html
i18n/css3-text-line-break-opclns-108.html
i18n/css3-text-line-break-opclns-109.html
i18n/css3-text-line-break-opclns-110.html
i18n/css3-text-line-break-opclns-111.html
i18n/css3-text-line-break-opclns-112.html
i18n/css3-text-line-break-opclns-113.html
i18n/css3-text-line-break-opclns-114.html
i18n/css3-text-line-break-opclns-115.html
i18n/css3-text-line-break-opclns-116.html
i18n/css3-text-line-break-opclns-117.html
i18n/css3-text-line-break-opclns-119.html
i18n/css3-text-line-break-opclns-120.html
i18n/css3-text-line-break-opclns-121.html
i18n/css3-text-line-break-opclns-122.html
i18n/css3-text-line-break-opclns-123.html
i18n/css3-text-line-break-opclns-124.html
i18n/css3-text-line-break-opclns-125.html
i18n/css3-text-line-break-opclns-126.html
i18n/css3-text-line-break-opclns-127.html
i18n/css3-text-line-break-opclns-128.html
i18n/css3-text-line-break-opclns-129.html
i18n/css3-text-line-break-opclns-130.html
i18n/css3-text-line-break-opclns-131.html
i18n/css3-text-line-break-opclns-132.html
i18n/css3-text-line-break-opclns-133.html
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i18n/css3-text-line-break-opclns-135.html
i18n/css3-text-line-break-opclns-136.html
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i18n/css3-text-line-break-opclns-138.html
i18n/css3-text-line-break-opclns-139.html
i18n/css3-text-line-break-opclns-140.html
i18n/css3-text-line-break-opclns-141.html
i18n/css3-text-line-break-opclns-142.html
i18n/css3-text-line-break-opclns-143.html
i18n/css3-text-line-break-opclns-144.html
i18n/css3-text-line-break-opclns-145.html
i18n/css3-text-line-break-opclns-146.html
i18n/css3-text-line-break-opclns-147.html
i18n/css3-text-line-break-opclns-148.html
i18n/css3-text-line-break-opclns-149.html
i18n/css3-text-line-break-opclns-150.html
i18n/css3-text-line-break-opclns-151.html
i18n/css3-text-line-break-opclns-152.html
i18n/css3-text-line-break-opclns-153.html
i18n/css3-text-line-break-opclns-155.html
i18n/css3-text-line-break-opclns-156.html
i18n/css3-text-line-break-opclns-157.html
i18n/css3-text-line-break-opclns-158.html
i18n/css3-text-line-break-opclns-159.html
i18n/css3-text-line-break-opclns-160.html
i18n/css3-text-line-break-opclns-161.html
i18n/css3-text-line-break-opclns-162.html
i18n/css3-text-line-break-opclns-163.html
i18n/css3-text-line-break-opclns-164.html
i18n/css3-text-line-break-opclns-165.html
i18n/css3-text-line-break-opclns-166.html
i18n/css3-text-line-break-opclns-167.html
i18n/css3-text-line-break-opclns-168.html
i18n/css3-text-line-break-opclns-169.html
i18n/css3-text-line-break-opclns-170.html
i18n/css3-text-line-break-opclns-171.html
i18n/css3-text-line-break-opclns-200.html
i18n/css3-text-line-break-opclns-201.html
i18n/css3-text-line-break-opclns-202.html
i18n/css3-text-line-break-opclns-203.html
i18n/css3-text-line-break-opclns-204.html
i18n/css3-text-line-break-opclns-205.html
i18n/css3-text-line-break-opclns-206.html
i18n/css3-text-line-break-opclns-207.html
i18n/css3-text-line-break-opclns-208.html
i18n/css3-text-line-break-opclns-209.html
i18n/css3-text-line-break-opclns-210.html
i18n/css3-text-line-break-opclns-211.html
i18n/css3-text-line-break-opclns-212.html
i18n/css3-text-line-break-opclns-213.html
i18n/css3-text-line-break-opclns-214.html
i18n/css3-text-line-break-opclns-215.html
i18n/css3-text-line-break-opclns-217.html
i18n/css3-text-line-break-opclns-218.html
i18n/css3-text-line-break-opclns-219.html
i18n/css3-text-line-break-opclns-220.html
i18n/css3-text-line-break-opclns-221.html
i18n/css3-text-line-break-opclns-222.html
i18n/css3-text-line-break-opclns-223.html
i18n/css3-text-line-break-opclns-225.html
i18n/css3-text-line-break-opclns-226.html
While CSS does not fully define where [=soft wrap opportunities=] occur,
some controls are provided to distinguish common variations:
The 'line-break' property allows choosing various levels of “strictness”
for line breaking restrictions.
The 'word-break' property controls what types of letters
are glommed together to form unbreakable “words”,
causing CJK characters to behave like non-CJK text or vice versa,
enabling control over word detection in South East Asian Languages,
or allowing words to be grouped into phrases…
The 'hyphens' property controls whether automatic hyphenation
is allowed to break words in scripts that hyphenate.
The 'overflow-wrap' property allows the UA to take a break anywhere
in otherwise-unbreakable strings that would otherwise overflow.
Note: Unicode Standard Annex #14: Unicode Line Breaking Algorithm
defines a baseline behavior
for line breaking for all scripts in Unicode,
which is expected to be further tailored.
[[UAX14]]
More information on line breaking conventions
can be found in Requirements for Japanese Text Layout [[JLREQ]]
and Formatting Rules for Japanese Documents [[JIS4051]] for Japanese,
Requirements for Chinese Text Layout [[CLREQ]]
and General Rules for Punctuation [[ZHMARK]] for Chinese.
See also the
Internationalization Working Group’s
Language Enablement Index
which includes more information on additional languages.
[[TYPOGRAPHY]]
Any guidance on additional appropriate references
would be much appreciated.
line-breaking/line-breaking-028.html
line-breaking/line-breaking-029.html
shaping/shaping_lig-001.html
Breaking Rules for Letters: the 'word-break' property
Name: word-break
Value: normal | break-all | keep-all | manual | auto-phrase | break-word
Initial: normal
Applies to: text
Inherited: yes
Canonical order: n/a
Computed value: specified keyword
Animation type: discrete
inheritance.html
parsing/word-break-invalid.html
parsing/word-break-valid.html
parsing/word-break-computed.html
word-break/word-break-break-all-inline-001.html
word-break/word-break-break-all-inline-002.html
word-break/word-break-break-all-inline-003.html
word-break/word-break-break-all-inline-004.tentative.html
word-break/word-break-break-all-inline-005.html
word-break/word-break-break-all-inline-006.html
word-break/word-break-break-all-inline-007.tentative.html
word-break/word-break-break-all-inline-009.html
word-break/word-break-break-all-062.html
word-break/word-break-keep-all-063.html
This property specifies [=soft wrap opportunities=] between and within “words”,
i.e. where it is “normal” and permissible to break lines of text.
It focuses on breaks between letters,
and does not define whether and how [=soft wrap opportunities=]
are created by [=white space=] and [=other space separators=]
(though ''word-break/auto-phrase'' may suppress some),
nor around punctuation.
(See 'line-break' for controls affecting punctuation and small kana.)
word-break/word-break-keep-all-005.html
word-break/word-break-keep-all-006.html
word-break/word-break-keep-all-007.html
word-break/word-break-keep-all-008.html
word-break/word-break-min-content-003.html
word-space-transform/word-space-transform-013.html
word-space-transform/word-space-transform-014.html
In particular,
'word-break' controls whether a [=soft wrap opportunity=]
generally exists
between adjacent [=typographic letter units=],
treating non-[=letter=] [=typographic character units=]
belonging to the
NU,
AL,
AI,
or ID
Unicode line breaking classes
as [=typographic letter units=] for this purpose (only).
[[!UAX14]]
For example,
in some styles of CJK typesetting,
English words are allowed to break between any two letters,
rather than only at spaces or hyphenation points;
this can be enabled with ''word-break:break-all''.
An example of English text embedded in Japanese
being broken at an arbitrary point in the word.
As another example, Korean has two styles of line-breaking:
between any two Korean syllables (''word-break: normal'')
or, like English, mainly at spaces (''word-break: keep-all'').
각 줄의 마지막에 한글이 올 때 줄 나눔 기
준을 “글자” 또는 “어절” 단위로 한다.
각 줄의 마지막에 한글이 올 때 줄 나눔
기준을 “글자” 또는 “어절” 단위로 한다.
Ethiopic similarly has two styles of line-breaking,
either only breaking at [=word separators=] (''word-break: normal''),
or also allowing breaks between letters within a word (''word-break: break-all'').
Words break according to their customary rules,
as described [[#line-breaking|above]].
Korean, which commonly exhibits two different behaviors,
allows breaks between any two consecutive Hangul/Hanja.
For Ethiopic, which also exhibits two different behaviors,
such breaks within words are not allowed.
word-break/word-break-normal-001.html
word-break/word-break-normal-002.html
word-break/word-break-normal-003.html
word-break/word-break-normal-ar-000.html
word-break/word-break-normal-bo-000.html
word-break/word-break-normal-en-000.html
word-break/word-break-normal-hi-000.html
word-break/word-break-normal-ja-000.html
word-break/word-break-normal-ja-001.html
word-break/word-break-normal-ja-002.html
word-break/word-break-normal-ja-004.html
word-break/word-break-normal-km-000.html
word-break/word-break-normal-ko-000.html
word-break/word-break-normal-lo-000.html
word-break/word-break-normal-my-000.html
word-break/word-break-normal-tdd-000.html
word-break/word-break-normal-th-000.html
word-break/word-break-normal-th-001.html
word-break/word-break-normal-zh-000.html
word-break/word-break-normal-ethiopic.html
Some writing systems require specific processing
to obtain the customarily expected [=soft wrap opportunities=],
as described in [[#analytical-word-breaking]].
break-all
Breaking is allowed within “words”:
specifically,
in addition to [=soft wrap opportunities=] allowed for ''word-break/normal'',
any [=typographic letter units=]
(and any [=typographic character units=] resolving to the
NU (“numeric”),
AL (“alphabetic”),
or SA (“Southeast Asian”)
line breaking classes [[!UAX14]])
are instead treated as ID
(“ideographic characters”)
for the purpose of line-breaking.
Hyphenation is not applied.
line-break/line-break-loose-hyphens-002.html
line-break/line-break-normal-hyphens-002.html
line-break/line-break-strict-hyphens-002.html
overflow-wrap/overflow-wrap-anywhere-006.html
white-space/break-spaces-006.html
white-space/break-spaces-008.html
white-space/break-spaces-before-first-char-004.html
white-space/break-spaces-before-first-char-005.html
white-space/break-spaces-before-first-char-006.html
white-space/break-spaces-before-first-ideographic-char-004.html
white-space/break-spaces-before-first-ideographic-char-005.html
white-space/break-spaces-before-first-ideographic-char-006.html
word-break/break-boundary-2-chars-002.html
word-break/word-break-break-all-000.html
word-break/word-break-break-all-001.html
word-break/word-break-break-all-002.html
word-break/word-break-break-all-003.html
word-break/word-break-break-all-005.html
word-break/word-break-break-all-006.html
word-break/word-break-break-all-010.html
word-break/word-break-break-all-012.html
word-break/word-break-break-all-013.html
word-break/word-break-break-all-014.html
word-break/word-break-break-all-015.html
word-break/word-break-break-all-016.html
word-break/word-break-break-all-017.html
word-break/word-break-break-all-018.html
word-break/word-break-break-all-019.html
word-break/word-break-break-all-020.html
word-break/word-break-break-all-021.html
word-break/word-break-break-all-022.html
word-break/word-break-break-all-023.html
word-break/word-break-break-all-024.html
word-break/word-break-break-all-025.html
word-break/word-break-break-all-026.html
word-break/word-break-break-all-027.html
word-break/word-break-break-all-028.html
word-break/word-break-break-all-029.html
word-break/word-break-break-all-030.html
word-break/word-break-break-all-031.html
word-break/word-break-break-all-032.html
word-break/word-break-break-all-ethiopic.html
word-break/word-break-break-all-inline-001.html
word-break/word-break-break-all-inline-002.html
word-break/word-break-break-all-inline-003.html
word-break/word-break-break-all-inline-004.tentative.html
word-break/word-break-break-all-inline-005.html
word-break/word-break-break-all-inline-006.html
word-break/word-break-break-all-inline-007.tentative.html
word-break/word-break-break-all-inline-008.html
word-break/word-break-break-all-inline-009.html
word-break/word-break-break-all-inline-010.tentative.html
Note: This value does not affect
whether there are [=soft wrap opportunities=]
around punctuation characters.
To allow breaks anywhere, see ''line-break: anywhere''.
white-space/break-spaces-before-first-char-011.html
white-space/break-spaces-before-first-ideographic-char-011.html
word-break/word-break-break-all-ethiopic.html
Note: This option enables the other common behavior for Ethiopic.
It is also often used in a context where
the text consists predominantly of CJK characters
with only short non-CJK excerpts,
and it is desired that the text be better distributed on each line.
keep-all
Breaking is forbidden within “words”:
implicit [=soft wrap opportunities=] between [=typographic letter units=]
(or other [=typographic character units=]
belonging to the
NU,
AL,
AI,
or ID
Unicode line breaking classes [[!UAX14]])
are suppressed,
i.e. breaks are prohibited between pairs of such characters
(regardless of 'line-break' settings other than ''line-break/anywhere'')
except where opportunities exist due to [[#lexical-breaking]].
Otherwise this option is equivalent to ''word-break/normal''.
In this style, sequences of CJK characters do not break.
word-break/word-break-keep-all-000.html
word-break/word-break-keep-all-001.html
word-break/word-break-keep-all-002.html
word-break/word-break-keep-all-003.html
word-break/word-break-keep-all-009.html
word-break/word-break-keep-all-010.html
white-space/break-spaces-with-word-break-001.html
Note: This is the other common behavior for Korean
(which uses [=spaces=] between words),
and is also useful for mixed-script text where CJK snippets are mixed
into another language that uses [=spaces=] for separation.
manual
Behaves the same as ''word-break/normal'',
except that
[[#lexical-breaking]] must not be performed.
Specifically,
[=typographic character units=] with class SA in [[!UAX14]]
must be treated as if they had class AL
(i.e. assuming a value of 'line-break' other than ''line-break/anywhere'',
there is no [=soft wrap opportunity=]
between pairs of such characters).
word-break/word-break-manual-001.html
Note: This value does not affect
syllable-based [=soft wrap opportunities=] within words
in languages such as Balinese.
(See [[#orthographic-breaking]]
for some discussion of such writing systems.)
Issue: alternatively, this value could be based
on ''keep-all'' rather than ''word-break/normal''.
Yet another variant is to merge this behavior
with ''keep-all''.
Note: Some Southeast Asian languages are commonly misdetected by user agents.
With ''word-break: normal'',
they would then apply inappropriate language-specific logic
to find wrapping opportunities,
and place them inappropriately.
For instance,
many languages other than Thai are written using the Thai script,
and line-breaking them as if they were Thai
will generally produce inadequate--
and possibly confusing--
results.
When this occurs,
this value enables authors to turn off
the word boundary detection
built into user agents for ''word-break: normal'',
so that they can manually mark up the text to indicate wrapping opportunities
and obtain sensible results.
Authors using this value
are expected to manually indicate word boundaries for Southeast Asian languages,
using <{wbr}> or U+200B.
Otherwise, there will be no [=soft wrap opportunity=]
and the text may overflow.
auto-phrase
Behaves the same as ''word-break/normal'',
except that
this value directs the user agent to perform language-specific content analysis
to prioritize keeping natural phrases (of multiple words) together.
If the [=content language=] of the element is unknown,
or if the user agent does not know how to [=detect phrase boundaries=]
for that particular language,
this value must behave as ''word-break/normal''.
Otherwise,
the user agent should [=detect phrase boundaries=]
and suppress [=soft wrap opportunities=]
within each phrase.
word-break/auto-phrase/word-break-auto-phrase-001.html
word-break/auto-phrase/word-break-auto-phrase-002.html
word-break/auto-phrase/word-break-auto-phrase-003.html
word-break/auto-phrase/word-break-auto-phrase-004.html
word-break/auto-phrase/word-break-auto-phrase-005.html
word-break/auto-phrase/word-break-auto-phrase-005.html
word-break/auto-phrase/word-break-auto-phrase-007.html
word-break/auto-phrase/word-break-auto-phrase-009.html
word-break/auto-phrase/word-break-auto-phrase-fallback-001.html
word-break/auto-phrase/word-break-auto-phrase-fallback-002.html
word-break/auto-phrase/word-break-auto-phrase-fallback-003.html
word-break/auto-phrase/word-break-auto-phrase-intrinsic-001.html
word-break/auto-phrase/word-break-auto-phrase-overflow-001.html
word-break/auto-phrase/word-break-auto-phrase-wbr-nobr-001.html
word-break/auto-phrase/word-break-auto-phrase-wbr-nobr-002.html
Regardless of the [=content language=]
and support for [=phrase boundary detection=],
[=hyphenation opportunities=] are suppressed
as if ''hyphens: none'' had been specified.
word-break/auto-phrase/word-break-auto-phrase-006.html
word-break/auto-phrase/word-break-auto-phrase-008.html
Note: Whether a word boundary detection system designed for one language
is suitable for some or all dialects of that language is somewhat subjective,
and this specifications leaves it at the discretion of the user agent.
Even if a detection system is not able to cope
with all nuances of a particular dialect,
it may be reasonable to claim support
if the detection correctly recognizes word boundaries most of the time.
However, the user agent would do a disservice to authors and users
if it claimed support for languages
where it fails to detect most word boundaries
or has a high error rate.
If a user agent has a word-boundary detection system for Cantonese
that is not suitable for the broader set of Chinese languages,
''word-break/auto-phrase'' should have an effect on content marked as
''lang=yue'', ''lang=zh-yue'', or ''lang=zh-HK'',
but not ''lang=zh'' or ''lang=zh-Hant''.
However, if the user agent supports a generic word-boundary detection system
that is suitable for Chinese in general,
''word-break/auto-phrase'' should have an effect on content
marked with the broad ''lang=zh'' characterization,
as well as any more specific ones,
such as ''lang=zh-yue'', ''lang=zh-Hant-HK'', ''lang=zh-Hans-SG'', or ''lang=zh-hak''.
Symbols that line-break the same way as letters of a particular category
are affected the same way as those letters.
User agents must not,
in response to any value of this property,
suppress [=soft wrap opportunities=] which are:
* introduced by the <{wbr}> HTML element or U+200B ZERO WIDTH SPACE
word-break/auto-phrase/word-break-auto-phrase-006.html
word-break/auto-phrase/word-break-auto-phrase-wbr-nobr-001.html
* required by the 'line-break' property
* surrounding atomic inlines
Note: To control additional break opportunities
available only in the case of overflow,
see 'overflow-wrap'.
The effects of 'word-break'
are taken into account when computing [=intrinsic sizes=].
Here’s a mixed-script sample text:
这是一些汉字 and some Latin و کمی خط عربی และตัวอย่างการเขียนภาษาไทย በጽሑፍ፡ማራዘሙን፡አንዳንድ፡
The break-points are determined as follows (indicated by ‘·’):
Japanese is usually typeset allowing line breaks between each syllable.
However, it is sometimes preferred to suppress these wrapping opportunities
and to only allow wrapping at the end of certain sentence fragments.
This is most commonly done in very short pieces of text,
such as headings and table or figure captions.
This can be achieved manually by marking the allowed wrapping points
with <{wbr}> or U+200B ZERO WIDTH SPACE,
and suppressing the other ones using ''word-break: keep-all''.
Alternatively,
in user agents that support detection of phrases boundaries in Japanese,
the same results can be achieved automatically
by using
''word-break: auto-phrase''
(assuming the [=content language=] is specified).
Sample markup and style rule
Expected rendering
Result in your browser
<h1>
窓ぎわの<wbr>トットちゃん
</h1>
h1 {
word-break: normal;
}
窓ぎわのトッ
トちゃん
窓ぎわのトットちゃん
<h1>
窓ぎわの<wbr>トットちゃん
</h1>
h1 {
word-break: keep-all;
}
窓ぎわの
トットちゃん
窓ぎわのトットちゃん
<h1 lang=ja>
窓ぎわのトットちゃん
</h1>
h1 {
word-break: auto-phrase;
}
窓ぎわの
トットちゃん
窓ぎわのトットちゃん
When shaping scripts such as Arabic
are allowed to break within words due to ''word-break/break-all''
the characters must still be shaped
as if the word were not broken.
word-break/word-break-break-all-004.html
For compatibility with legacy content,
the 'word-break' property also supports
a deprecated break-word keyword.
When specified, this has the same effect as
''word-break: normal'' and ''overflow-wrap: anywhere'',
regardless of the actual value of the 'overflow-wrap' property.
white-space/pre-wrap-008.html
white-space/pre-wrap-016.html
word-break/word-break-break-word-overflow-wrap-interactions.html
word-break/word-break-break-word-crash-001.html
white-space/break-spaces-003.html
white-space/break-spaces-004.html
white-space/break-spaces-008.html
white-space/break-spaces-before-first-char-010.html
white-space/break-spaces-before-first-ideographic-char-010.html
word-break/word-break-min-content-001.html
word-break/word-break-min-content-002.html
word-break/word-break-min-content-003.html
word-break/word-break-min-content-004.html
word-break/word-break-min-content-005.html
word-break/word-break-min-content-006.html
white-space/break-spaces-with-ideographic-space-002.html
white-space/break-spaces-with-ideographic-space-004.html
white-space/break-spaces-with-ideographic-space-006.html
white-space/break-spaces-with-ideographic-space-008.html
white-space/break-spaces-with-ideographic-space-009.html
word-break/word-break-min-content-007.html
Analytical Word Breaking
Lexical Word Breaking
To provide the expected ''word-break/normal'' behavior
for Southeast Asian languages,
[=typographic character units=] with line breaking class SA in [[!UAX14]]
must be treated as if they had class AL.
However, the user agent must additionally
analyze the content of a run of such characters
to [=detect word boundaries=]
and treat each boundary as a [=soft wrap opportunities=].
word-break/word-break-normal-002.html
word-break/word-break-normal-003.html
word-break/word-break-normal-km-000.html
word-break/word-break-normal-lo-000.html
word-break/word-break-normal-my-000.html
word-break/word-break-normal-tdd-000.html
word-break/word-break-normal-th-000.html
word-break/word-break-normal-th-001.html
As various languages can be written in scripts
which use the characters with class SA,
if the [=content language=] is known,
the user agent should use this information
to tailor its analysis.
word-break/word-break-normal-tdd-000.html
Orthographic Breaking
For scripts (such as Balinese) that use line breaking based on orthographic syllables,
the UA must analyze the content
to find the correct points to insert [=soft wrap opportunities=].
Note: At the time of writing,
Unicode does not define how to perform this analysis,
and treats all characters in these writing systems
as having line breaking class AL.
However,
[[L2-22-080R inline|a proposal]] has been made to solve that issue.
Even though it is not final,
it can be informative to consult.
[[L2-22-080R]]
Fallback Breaking
In order to avoid unexpected overflow,
if the user agent is unable to perform the requisite lexical
or orthographic analysis
for line breaking any [=content language=] that requires it--
for example due to lacking a dictionary
for languages written in characters with class SA--
it must assume a [=soft wrap opportunity=]
between pairs of [=typographic letter units=] in that writing system.
line-breaking/line-breaking-023.html
line-breaking/line-breaking-024.html
line-breaking/line-breaking-025.html
line-breaking/line-breaking-026.html
line-breaking/line-breaking-027.html
Note: This provision is not triggered merely when
the UA fails to find a word boundary in a particular text run;
the text run may well be a single unbreakable word.
It applies for example
when a text run is composed of Khmer characters (U+1780 to U+17FF)
if the user agent does not know how to determine
word boundaries in Khmer.
Expressing User Preferences for Phrase-based Line Breaking
User agents may activate
language-specific content analysis
described in ''word-break/auto-phrase''
in response to user preferences.
User agents with this behavior must do this
by setting the [=declared value=] of 'word-break' to ''word-break/auto-phrase''
in the [=user origin=].
Note: This allows authors to detect
whether or not this feature is enabled by calling {{getComputedStyle()}},
or to override it in the [=author origin=] where appropriate.
Line Breaking Strictness: the 'line-break' property
Name: line-break
Value: auto | loose | normal | strict | anywhere
Initial: auto
Applies to: text
Inherited: yes
Canonical order: n/a
Computed value: specified keyword
Animation type: discrete
inheritance.html
parsing/line-break-valid.html
parsing/line-break-invalid.html
parsing/line-break-computed.html
animations/line-break-no-interpolation.html
This property specifies the strictness of line-breaking rules applied
within an element:
especially how [=wrapping=] interacts with punctuation and symbols.
Values have the following meanings:
auto
The UA determines the set of line-breaking restrictions to use,
and it may vary the restrictions based on the length of the line;
e.g., use a less restrictive set of line-break rules for short lines.
loose
Breaks text using the least restrictive set of line-breaking
rules. Typically used for short lines, such as in newspapers.
normal
Breaks text using the most common set of line-breaking rules.
strict
Breaks text using the most stringent set of line-breaking rules.
anywhere
There is a [=soft wrap opportunity=] around every [=typographic character unit=],
including around any punctuation character
or [=preserved white spaces=],
or in the middle of words,
disregarding any prohibition against line breaks,
even those introduced by characters with the GL, WJ, or ZWJ line breaking classes
or mandated by the 'word-break' property.
[[UAX14]]
The different wrapping opportunities must not be prioritized.
Hyphenation is not applied.
line-break/line-break-anywhere-001.html
line-break/line-break-anywhere-002.html
line-break/line-break-anywhere-003.html
line-break/line-break-anywhere-004.html
line-break/line-break-anywhere-005.html
line-break/line-break-anywhere-006.html
line-break/line-break-anywhere-007.html
line-break/line-break-anywhere-008.html
line-break/line-break-anywhere-009.html
line-break/line-break-anywhere-010.html
line-break/line-break-anywhere-011.html
line-break/line-break-anywhere-012.html
line-break/line-break-anywhere-013.html
line-break/line-break-anywhere-014.html
line-break/line-break-anywhere-015.html
line-break/line-break-anywhere-016.html
line-break/line-break-anywhere-017.html
line-break/line-break-anywhere-and-white-space-001.html
line-break/line-break-anywhere-and-white-space-002.html
line-break/line-break-anywhere-and-white-space-003.html
line-break/line-break-anywhere-and-white-space-004.html
line-break/line-break-anywhere-and-white-space-005.html
line-break/line-break-anywhere-and-white-space-006.html
line-break/line-break-anywhere-and-white-space-007.html
line-break/line-break-anywhere-and-white-space-008.html
line-break/line-break-anywhere-and-white-space-009.html
line-break/line-break-anywhere-and-white-space-009.html
line-break/line-break-anywhere-overrides-uax-behavior-001.html
line-break/line-break-anywhere-overrides-uax-behavior-002.html
line-break/line-break-anywhere-overrides-uax-behavior-003.html
line-break/line-break-anywhere-overrides-uax-behavior-004.html
line-break/line-break-anywhere-overrides-uax-behavior-005.html
line-break/line-break-anywhere-overrides-uax-behavior-006.html
line-break/line-break-anywhere-overrides-uax-behavior-007.html
line-break/line-break-anywhere-overrides-uax-behavior-008.html
line-break/line-break-anywhere-overrides-uax-behavior-009.html
line-break/line-break-anywhere-overrides-uax-behavior-010.html
line-break/line-break-anywhere-overrides-uax-behavior-011.html
line-break/line-break-anywhere-overrides-uax-behavior-012.html
line-break/line-break-anywhere-overrides-uax-behavior-013.html
line-break/line-break-anywhere-overrides-uax-behavior-014.html
line-break/line-break-anywhere-overrides-uax-behavior-015.html
line-break/line-break-anywhere-overrides-uax-behavior-016.html
line-break/line-break-shaping-001.html
white-space/break-spaces-before-first-char-007.html
white-space/break-spaces-before-first-char-011.html
white-space/break-spaces-before-first-ideographic-char-007.html
white-space/break-spaces-before-first-ideographic-char-011.html
Note: This value triggers the line breaking rules typically seen in terminals.
Note: This values only creates [=soft wrap opportunities=]
between [=typographic character units=],
not within them.
Consequently, the CM and SG
Unicode line breaking classes must be honored.
[[UAX14]]
Note: ''line-break/anywhere'' only allows [=preserved white spaces=]
at the end of the line
to be wrapped to the next line
when 'white-space' is set to ''white-space/break-spaces'',
because in other cases:
[=preserved white space=] at the end/start of the line is discarded
(''white-space/normal'', ''white-space/pre-line'')
wrapping is forbidden altogether (''white-space/nowrap'', ''pre'')
the [=preserved white space=] [=hang=] (''pre-wrap'').
When it does have an effect on [=preserved white space=],
with ''white-space: break-spaces'',
it allows breaking before the first space of a sequence,
which ''break-spaces'' on its own does not.
CSS distinguishes between four levels of strictness
in the rules for text wrapping.
The precise set of rules in effect for each of
''line-break/loose'',
''line-break/normal'',
and ''line-break/strict''
is up to the UA
and should follow language conventions.
However, for these three keywords, this specification does require that:
The following breaks are forbidden in ''strict'' line breaking
and allowed in ''line-break/normal'' and ''loose'':
breaks before Japanese small kana
or the Katakana-Hiragana prolonged sound mark,
i.e. characters
from the Unicode line breaking class CJ.
[[!UAX14]]
line-break/line-break-loose-011.xht
line-break/line-break-loose-012.xht
line-break/line-break-normal-011.xht
line-break/line-break-normal-012.xht
line-break/line-break-strict-011.xht
line-break/line-break-strict-012.xht
i18n/ja/css-text-line-break-ja-cj-loose.html
i18n/ja/css-text-line-break-ja-cj-normal.html
i18n/ja/css-text-line-break-ja-cj-strict.html
i18n/zh/css-text-line-break-zh-cj-loose.html
i18n/zh/css-text-line-break-zh-cj-normal.html
i18n/zh/css-text-line-break-zh-cj-strict.html
i18n/other-lang/css-text-line-break-de-cj-loose.html
i18n/other-lang/css-text-line-break-de-cj-normal.html
i18n/other-lang/css-text-line-break-de-cj-strict.html
i18n/unknown-lang/css-text-line-break-cj-loose.html
i18n/unknown-lang/css-text-line-break-cj-normal.html
i18n/unknown-lang/css-text-line-break-cj-strict.html
The following breaks are allowed for ''line-break/normal''
and ''loose'' line breaking
if the [=writing system=] is Chinese
or Japanese,
and are otherwise forbidden:
The following breaks are allowed for ''loose'' line breaking
if the preceding character
belongs to the Unicode line breaking class ID
[[!UAX14]]
(including when the preceding character
is treated as ID
due to ''word-break: break-all''),
and are otherwise forbidden:
breaks between inseparable characters
(such as ‥ U+2025, … U+2026)
i.e. characters from the Unicode line breaking class IN.
[[!UAX14]]
line-break/line-break-loose-015.xht
line-break/line-break-normal-015a.xht
line-break/line-break-normal-015b.xht
line-break/line-break-strict-015a.xht
line-break/line-break-strict-015b.xht
i18n/ja/css-text-line-break-ja-in-loose.html
i18n/ja/css-text-line-break-ja-in-normal.html
i18n/ja/css-text-line-break-ja-in-strict.html
i18n/zh/css-text-line-break-zh-in-loose.html
i18n/zh/css-text-line-break-zh-in-normal.html
i18n/zh/css-text-line-break-zh-in-strict.html
i18n/other-lang/css-text-line-break-de-in-loose.html
i18n/other-lang/css-text-line-break-de-in-normal.html
i18n/other-lang/css-text-line-break-de-in-strict.html
i18n/unknown-lang/css-text-line-break-in-loose.html
i18n/unknown-lang/css-text-line-break-in-normal.html
i18n/unknown-lang/css-text-line-break-in-strict.html
The following breaks are allowed for ''loose''
if the [=writing system=] is Chinese
or Japanese
and are otherwise forbidden:
breaks before suffixes:
Characters with the Unicode line breaking class PO
[[!UAX14]]
and the [=East Asian Width property=]
[[!UAX11]]
Ambiguous,
Fullwidth,
or Wide.
line-break/line-break-loose-017a.xht
line-break/line-break-loose-017b.xht
line-break/line-break-normal-017a.xht
line-break/line-break-normal-017b.xht
line-break/line-break-strict-017a.xht
line-break/line-break-strict-017b.xht
i18n/ja/css-text-line-break-ja-po-loose.html
i18n/ja/css-text-line-break-ja-po-normal.html
i18n/ja/css-text-line-break-ja-po-strict.html
i18n/zh/css-text-line-break-zh-po-loose.html
i18n/zh/css-text-line-break-zh-po-normal.html
i18n/zh/css-text-line-break-zh-po-strict.html
i18n/other-lang/css-text-line-break-de-po-loose.html
i18n/other-lang/css-text-line-break-de-po-normal.html
i18n/other-lang/css-text-line-break-de-po-strict.html
i18n/unknown-lang/css-text-line-break-po-loose.html
i18n/unknown-lang/css-text-line-break-po-normal.html
i18n/unknown-lang/css-text-line-break-po-strict.html
breaks after prefixes:
Characters with the Unicode line breaking class PR
[[!UAX14]]
and the [=East Asian Width property=]
[[!UAX11]]
Ambiguous,
Fullwidth,
or Wide.
line-break/line-break-loose-018.xht
line-break/line-break-normal-018.xht
line-break/line-break-strict-018.xht
i18n/ja/css-text-line-break-ja-pr-loose.html
i18n/ja/css-text-line-break-ja-pr-normal.html
i18n/ja/css-text-line-break-ja-pr-strict.html
i18n/zh/css-text-line-break-zh-pr-loose.html
i18n/zh/css-text-line-break-zh-pr-normal.html
i18n/zh/css-text-line-break-zh-pr-strict.html
i18n/other-lang/css-text-line-break-de-pr-loose.html
i18n/other-lang/css-text-line-break-de-pr-normal.html
i18n/other-lang/css-text-line-break-de-pr-strict.html
i18n/unknown-lang/css-text-line-break-pr-loose.html
i18n/unknown-lang/css-text-line-break-pr-normal.html
i18n/unknown-lang/css-text-line-break-pr-strict.html
Note: The requirements listed above
only create distinctions in CJK text.
In an implementation that matches only the rules above,
and no additional rules,
'line-break' would only affect CJK code points
unless the writing system is tagged as
Chinese or Japanese.
Future levels may add additional specific rules
for other writing systems and languages
as their requirements become known.
As UAs can add additional distinctions
between ''line-break/strict''/''line-break/normal''/''line-break/loose'' modes,
these values can exhibit differences in other writing systems as well.
For example, a UA with sufficiently-advanced Thai language processing ability
could choose to map different levels of strictness in Thai line-breaking
to these keywords,
e.g. disallowing breaks within compound words in ''line-break/strict'' mode
(e.g. breaking ตัวอย่างการเขียนภาษาไทย as ตัวอย่าง·การเขียน·ภาษาไทย)
while allowing more breaks in ''line-break/loose''
(ตัวอย่าง·การ·เขียน·ภาษา·ไทย).
Note: While user agents can refer to [[!UAX14]] as a starting point
for their line-breaking implementation,
the following deviations could be desirable
for maximum interoperability with existing implementations:
- Not introducing a line break opportunity between
U+0021 (Exclamation Mark, !) and
a letter ([=Unicode general category=] L).
This prevents a break in the string “!important”.
- Not introducing a line break opportunity between
U+002F (Solidus, /) and
a letter ([=Unicode general category=] L).
This prevents a break in dates such as “23/Jan/2024”.
- Not introducing a line break opportunity between
U+007C (Vertical Line, |) and
a letter ([=Unicode general category=] L).
- Not introducing a line break opportunity between
U+002D (Hyphen-Minus `-`) and
a digit ([=Unicode general category=] Nd)
if the codepoint prior to the hyphen was _not_ a letter or digit
([=Unicode general category=] L or Nd).
This prevents breaking after the minus sign before a number
such as in “-13”
whilst allowing breaks after the hyphen in “ABCD-1234” and “1234-5678”
which may appear in long URLs, for example.
Note: The CSSWG recognizes that in a future edition of the specification
finer control over line breaking may be necessary
to satisfy high-end publishing requirements.
Hyphenation: Morphological Breaking Within Words
Hyphenation Control: the 'hyphens' property
Hyphenation
is the controlled splitting of words
where they usually would not be allowed to break
to improve the layout of paragraphs,
typically splitting words at syllabic or morphemic boundaries
and often visually indicating the split
(usually by inserting a hyphen, U+2010).
In some cases, hyphenation may also alter the spelling of a word.
Regardless, hyphenation is a rendering effect only:
it must have no effect on the underlying document content
or on text selection or searching.
hyphens/hyphens-character.html
hyphens/hyphens-vertical-001.html
hyphens/hyphens-vertical-002.html
Hyphenation practices vary across languages,
and can involve not just inserting a hyphen before the line break,
but inserting a hyphen after the break (or both),
inserting a different character than U+2010,
or changing the spelling of the word.
Language
Unbroken
Before
After
English
Unbroken
Un‐
broken
Dutch
cafeetje
café‐
tje
Hungarian
Összeg
Ösz‐
szeg
Mandarin
tú’àn
tú‐
àn
àizēng‐fēnmíng
àizēng‐
‐fēnmíng
Uyghur
Cree
hyphens/i18n/hyphens-i18n-auto-001.html
hyphens/i18n/hyphens-i18n-auto-002.html
hyphens/i18n/hyphens-i18n-auto-003.html
hyphens/i18n/hyphens-i18n-auto-004.html
hyphens/i18n/hyphens-i18n-auto-005.html
hyphens/i18n/hyphens-i18n-auto-006.html
Hyphenation occurs
when the line breaks at a valid hyphenation opportunity,
which is a type of [=soft wrap opportunity=]
that exists within a word where [=hyphenation=] is allowed.
In CSS [=hyphenation opportunities=] are controlled
with the 'hyphens' property.
CSS Text Level 3 does not define the exact rules for [=hyphenation=];
however UAs are strongly encouraged
to optimize their choice of break points
and to chose language-appropriate hyphenation points.
hyphens/hyphens-overflow-001.html
Note: The [=soft wrap opportunity=] introduced by
the U+002D - HYPHEN-MINUS character
or the U+2010 ‐ HYPHEN character
is not a [=hyphenation opportunity=],
as no visual indication of the split is created when wrapping:
these characters are visible whether the line is wrapped at that point or not.
Hyphenation opportunities are considered when calculating
[=min-content size|min-content intrinsic sizes=].
hyphens/hyphens-auto-min-content.html
Note: This allows tables to hyphenate their contents
instead of overflowing their containing block,
which is particularly important in long-word languages like German.
Name: hyphens
Value: none | manual | auto
Initial: manual
Applies to: text
Inherited: yes
Canonical order: n/a
Computed value: specified keyword
Animation type: discrete
inheritance.html
parsing/hyphens-valid.html
parsing/hyphens-invalid.html
parsing/hyphens-computed.html
hyphens/hyphens-auto-inline-010.html
hyphens/hyphens-manual-inline-010.html
hyphens/hyphens-manual-inline-011.html
hyphens/hyphens-manual-inline-012.html
animations/hyphen-no-interpolation.html
This property controls whether [=hyphenation=] is allowed to create more
[=soft wrap opportunities=] within a line of text.
Values have the following meanings:
none
Words are not hyphenated,
even if characters inside the word
explicitly define [=hyphenation opportunities=].
Note: This does not suppress the existing [=soft wrap opportunities=]
introduced by always visible characters such as
U+002D - HYPHEN-MINUS
or U+2010 ‐ HYPHEN.
hyphens/hyphens-none-011.html
hyphens/hyphens-none-012.html
hyphens/hyphens-none-013.html
hyphens/hyphens-none-014.html
hyphens/hyphens-none-015.html
hyphens/hyphens-none-shy-on-2nd-line-001.html
manual
Words are only hyphenated where there are characters inside the word
that explicitly suggest [=hyphenation opportunities=].
The UA must use the appropriate language-specific hyphenation character(s)
and should apply any appropriate spelling changes
just as for automatic hyphenation at the same point.
hyphens/hyphens-overflow-001.html
hyphens/hyphens-manual-010.html
hyphens/hyphens-manual-011.html
hyphens/hyphens-manual-012.html
hyphens/hyphens-manual-013.html
hyphens/hyphens-out-of-flow-001.html
hyphens/hyphens-shaping-001.html
hyphens/hyphens-shaping-002.html
hyphens/hyphens-span-001.html
hyphens/shy-styling-001.html
hyphens/i18n/hyphens-i18n-manual-001.html
hyphens/i18n/hyphens-i18n-manual-002.html
hyphens/i18n/hyphens-i18n-manual-003.html
hyphens/i18n/hyphens-i18n-manual-004.html
hyphens/i18n/hyphens-i18n-manual-005.html
hyphens/hyphens-vertical-001.html
hyphens/hyphens-vertical-002.html
hyphens/hyphens-vertical-003.html
hyphens/hyphens-vertical-004.html
hyphens/hyphens-vs-float-clearance-002.html
In Unicode, U+00AD is a conditional "soft hyphen"
and U+2010 is an unconditional hyphen.
Unicode Standard Annex #14
describes the role of soft hyphens in
Unicode line breaking.
[[!UAX14]]
In HTML,
­ represents the soft hyphen character,
which suggests a hyphenation opportunity.
ex­ample
auto
Words may be broken at [=hyphenation opportunities=]
determined automatically by a language-appropriate hyphenation resource
in addition to those indicated explicitly by a conditional hyphen.
Automatic [=hyphenation opportunities=] elsewhere within a word must be ignored
if the word contains a conditional hyphen
(­ or U+00AD SOFT HYPHEN),
in favor of the conditional hyphen(s).
However, if, even after breaking at such opportunities,
a portion of that word is still too long to fit on one line,
an automatic hyphenation opportunity may be used.
hyphens/hyphens-auto-control.html
hyphens/hyphens-auto-001.html
hyphens/hyphens-auto-002.html
hyphens/hyphens-auto-003.html
hyphens/hyphens-auto-004.html
hyphens/hyphens-auto-005.html
hyphens/hyphens-auto-010.html
hyphens/hyphens-out-of-flow-002.html
hyphens/hyphens-span-002.html
hyphens/hyphens-auto-and-contenteditable-crash.html
hyphens/hyphens-auto-last-word-001.html
hyphens/hyphens-punctuation-001.html
hyphens/hyphens-vs-float-clearance-001.html
Correct automatic hyphenation requires a hyphenation resource
appropriate to the language of the text being broken.
The UA must therefore only automatically hyphenate text
for which the content language is known
and for which it has an appropriate hyphenation resource.
hyphens/hyphens-auto-001.html
Authors should correctly tag their content’s [=content language|language=]
(e.g. using the HTML lang attribute
or XML xml:lang attribute)
in order to obtain correct automatic hyphenation.
The UA may use language-tailored heuristics
to exclude certain words
from automatic hyphenation.
For example, a UA might try to avoid hyphenation in proper nouns
by excluding words matching certain capitalization and punctuation patterns.
Such heuristics are not defined by this specification.
(Note that such heuristics will need to vary by language:
English and German, for example, have very different capitalization conventions.)
For the purpose of the 'hyphens' property,
what constitutes a “word” is UA-dependent.
However, inline element boundaries
and out-of-flow elements
must be ignored when determining word boundaries.
hyphens/hyphens-span-001.html
hyphens/hyphens-span-002.html
hyphens/hyphens-out-of-flow-001.html
hyphens/hyphens-out-of-flow-002.html
Any glyphs shown due to hyphenation
at a [=hyphenation opportunity=]
created by a conditional hyphen character
(such as U+00AD SOFT HYPHEN)
are represented by that character
and are styled according to the properties applied to it.
hyphens/shy-styling-001.html
When shaping scripts such as Arabic are allowed to break within words
due to hyphenation,
the characters must still be shaped
as if the word were not broken.
hyphens/hyphens-shaping-001.html
hyphens/hyphens-shaping-002.html
For example, if the Uyghur word “داميدى”
were hyphenated, it would appear as
not as
.
Hyphens: the 'hyphenate-character' property
Name: hyphenate-character
Value: auto | <>
Initial: auto
Applies to: text
Inherited: yes
Percentages: n/a
Computed value: specified keyword
Animation type: discrete
animations/hyphen-no-interpolation.html
parsing/hyphenate-character-computed.html
parsing/hyphenate-character-invalid.html
parsing/hyphenate-character-valid.html
This property specifies the string that is shown
between parts of hyphenated words.
Values have the following meanings:
auto
Specifies that the user agent should find an appropriate string
based on the content language’s typographic conventions,
possibly from the same source as the hyphenation dictionary.
<>
Specifies the string that appears
at the hyphenation break when hyphenating.
(The position of this string is not affected:
the UA must insert the string
according to the typographic conventions of the [=content language=],
defaulting to immediately before the hyphenation break.)
The UA may truncate the used value
to a limited number of typographic character units;
it must not truncate only part of a typographic character unit.
hyphens/hyphenate-character-003.html
hyphens/hyphenate-character-004.html
hyphens/hyphenate-character-005.html
hyphens/hyphenate-limit-chars-001.html
hyphens/hyphens-vertical-003.html
hyphens/hyphens-vertical-004.html
Note: Specifying the empty string ''""'' is valid,
and causes the UA to break at [=hyphenation opportunities=]
without inserting a visible hyphenation character.
hyphens/hyphenate-character-001.html
hyphens/hyphenate-character-002.html
The hyphen character (U+2010) is most typically used
to indicate that a word has been split.
However, 'hyphenate-character' can be used
to specify a different type of hyphen when necessary.
Note: Both hyphens triggered by automatic hyphenation
and hyphens triggered by soft hyphens
are rendered according to 'hyphenate-character'.
Hyphenation Size Limit: the 'hyphenate-limit-zone' property
Name: hyphenate-limit-zone
Value: <>
Initial: 0
Applies to: [=block containers=]
Inherited: yes
Percentages: refers to length of the line box
Computed value: computed <> value
Animation type: by computed value type
Is 'hyphenate-limit-zone' a good name? Comments/suggestions?
This property specifies the maximum amount of unfilled space
(before justification)
that may be left in the line box before hyphenation is triggered
to pull part of a word from the next line back up into the current line.
Hyphenation Character Limits: the 'hyphenate-limit-chars' property
Name: hyphenate-limit-chars
Value: [ auto | <> ]{1,3}
Initial: auto
Applies to: text
Inherited: yes
Percentages: n/a
Computed value: three values, each either the ''hyphenate-limit-chars/auto'' keyword or an integer
Animation type: by computed value type
animations/hyphen-no-interpolation.html
animations/hyphen-limit-chars-interpolation.html
parsing/hyphenate-limit-chars-computed.html
parsing/hyphenate-limit-chars-invalid.html
parsing/hyphenate-limit-chars-valid.html
This property specifies the minimum number of characters
in a hyphenated word.
If the word does not meet the required minimum number of characters
in the word / before the hyphen / after the hyphen,
then the word must not be hyphenated.
Nonspacing combining marks (Unicode General Category Mn)
and intra-word punctuation (Unicode General Category P*)
do not count towards the minimum.
If three values are specified,
the first value is the required minimum for the total characters in a word,
the second value is the minimum for characters before the hyphenation point,
and the third value is the minimum for characters after the hyphenation point.
If the third value is missing, it is the same as the second.
If the second value is missing, then it is ''hyphenate-limit-chars/auto''.
The auto value means that
the UA chooses a value that adapts to the current layout.
hyphens/hyphenate-limit-chars-001.html
Note: Unless the UA is able to calculate a better value,
it is suggested that ''hyphenate-limit-chars/auto'' means
2 for before and after, and 5 for the word total.
In the example below,
the minimum size of a hyphenated word is left to the UA
(which means it may vary depending on the language,
the length of the line, or other factors),
but the minimum number of characters
before and after the hyphenation point
is set to 3.
p { hyphenate-limit-chars: auto 3; }
Hyphenation Line Limits: the 'hyphenate-limit-lines' and 'hyphenate-limit-last' properties
Name: hyphenate-limit-lines
Value: no-limit | <>
Initial: no-limit
Applies to: block containers
Inherited: yes
Percentages: n/a
Computed value: specified keyword or integer
Animation type: by computed value type
This property indicates the maximum number of
successive hyphenated lines in an element.
The ''no-limit'' value means that there is no limit.
In some cases, user agents may not be able to honor the specified value.
(See overflow-wrap.)
It is not defined whether hyphenation introduced by such emergency breaking
influences nearby hyphenation points.
This property indicates hyphenation behavior at the end
of elements, column, pages, and spreads.
A spread is a set of two pages
that are visible to the reader at the same time.
Values have the following meanings:
none
No restrictions imposed.
always
The last full line of the element,
or the last line before any column, page, or spread break inside the element
should not be hyphenated.
column
The last line before any column, page, or spread break inside the element
should not be hyphenated.
page
The last line before page or spread break inside the element
should not be hyphenated.
spread
The last line before any spread break inside the element
should not be hyphenated.
p { hyphenate-limit-last: always }
div.chapter { hyphenate-limit-last: spread }
A paragraph may be formatted like this
when ''hyphenate-limit-last: none'' is set:
This is just a
simple example
to show Antarc-
tica.
With 'hyphenate-limit-last: always' one would get:
This is just a
simple example
to show
Antarctica.
Overflow Wrapping: the 'overflow-wrap'/'word-wrap' property
Name: overflow-wrap, word-wrap
Value: normal | break-word | anywhere
Initial: normal
Applies to: text
Inherited: yes
Canonical order: n/a
Computed value: specified keyword
Animation type: discrete
inheritance.html
parsing/overflow-wrap-invalid.html
parsing/overflow-wrap-valid.html
parsing/overflow-wrap-computed.html
parsing/word-wrap-invalid.html
parsing/word-wrap-valid.html
parsing/word-wrap-computed.html
overflow-wrap/overflow-wrap-anywhere-span-001.html
overflow-wrap/overflow-wrap-anywhere-span-002.html
overflow-wrap/overflow-wrap-break-word-span-001.html
overflow-wrap/overflow-wrap-break-word-span-002.html
overflow-wrap/overflow-wrap-break-word-long-crash.html
overflow-wrap/overflow-wrap-break-word-white-space-crash.html
overflow-wrap/overflow-wrap-break-word-white-space-crash-002.html
overflow-wrap/overflow-wrap-anywhere-inline-002.tentative.html
This property specifies whether the UA may break
at otherwise disallowed points within a line
to prevent overflow,
when an otherwise-unbreakable string is too long to fit within the line box.
It only has an effect when
'white-space' allows [=wrapping=]. Possible values:
overflow-wrap/overflow-wrap-002.html
normal
Lines may break only at allowed break points.
However,
the restrictions introduced by ''word-break: keep-all'' may be relaxed
to match ''word-break: normal''
if there are no otherwise-acceptable break points in the line.
overflow-wrap/overflow-wrap-004.html
overflow-wrap/overflow-wrap-normal-keep-all-001.html
Also, the restrictions introduced by ''word-break: auto-phrase''
are relaxed
if there are no otherwise-acceptable break points in the line:
If suppressing [=soft wrap opportunities=] within a particular phrase
would cause that phrase to overflow even when placed on an otherwise empty line,
the user agent must fall back
to the same [=soft wrap opportunities=] as ''word-break/normal''
within that phrase.
word-break/auto-phrase/word-break-auto-phrase-009.html
word-break/auto-phrase/word-break-auto-phrase-overflow-001.html
If that is not enough to prevent overflow,
suppression of [=hyphenation opportunities=] must also be abandoned
within each line that would overflow.
word-break/auto-phrase/word-break-auto-phrase-008.html
As an intermediary measure,
user agents may also detect multiple levels of phrases,
choosing to shorter ones
(possibly down to individual words)
when longer ones would lead to overflow.
The [=soft wrap opportunities=] obtained by relaxing the restrictions
introduced by ''word-break: keep-all'' and ''word-break: auto-phrase''
are not considered
when calculating [=min-content size|min-content intrinsic sizes=].
anywhere
An otherwise unbreakable sequence of [=characters=]
may be broken at an arbitrary point
if there are no otherwise-acceptable break points in the line.
Shaping characters are still shaped
as if the word were not broken,
and grapheme clusters must stay together as one unit.
No hyphenation character is inserted at the break point.
[=Soft wrap opportunities=] introduced by ''overflow-wrap/anywhere''
are considered
when calculating [=min-content size|min-content intrinsic sizes=].
overflow-wrap/overflow-wrap-min-content-size-001.html
overflow-wrap/overflow-wrap-min-content-size-002.html
overflow-wrap/overflow-wrap-min-content-size-003.html
overflow-wrap/overflow-wrap-anywhere-001.html
overflow-wrap/overflow-wrap-anywhere-003.html
overflow-wrap/overflow-wrap-anywhere-006.html
overflow-wrap/overflow-wrap-anywhere-007.html
overflow-wrap/overflow-wrap-anywhere-008.html
overflow-wrap/overflow-wrap-anywhere-009.html
overflow-wrap/overflow-wrap-anywhere-010.html
overflow-wrap/overflow-wrap-anywhere-011.html
overflow-wrap/overflow-wrap-anywhere-inline-001.html
overflow-wrap/overflow-wrap-anywhere-inline-002.tentative.html
overflow-wrap/overflow-wrap-anywhere-inline-003.tentative.html
overflow-wrap/overflow-wrap-anywhere-inline-004.tentative.html
overflow-wrap/overflow-wrap-anywhere-fit-content-001.html
overflow-wrap/overflow-wrap-min-content-size-005.html
overflow-wrap/overflow-wrap-min-content-size-007.html
overflow-wrap/overflow-wrap-cluster-002.html
overflow-wrap/overflow-wrap-shaping-002.html
white-space/break-spaces-before-first-char-009.html
white-space/break-spaces-before-first-char-013.html
white-space/break-spaces-before-first-ideographic-char-009.html
white-space/break-spaces-before-first-ideographic-char-013.html
word-break/word-break-min-content-001.html
word-break/word-break-min-content-002.html
word-break/word-break-min-content-003.html
word-break/word-break-min-content-004.html
word-break/word-break-min-content-005.html
word-break/word-break-min-content-006.html
white-space/pre-wrap-009.html
white-space/pre-wrap-010.html
white-space/break-spaces-with-overflow-wrap-002.html
white-space/break-spaces-with-overflow-wrap-004.html
white-space/break-spaces-with-overflow-wrap-006.html
white-space/break-spaces-with-overflow-wrap-008.html
white-space/break-spaces-with-overflow-wrap-010.html
white-space/text-wrap-balance-overflow-002.html
In the case of ''word-break: auto-phrase'',
these additional [=soft wrap opportunities=] are only introduced
if relaxing the restrictions introduced by ''word-break: auto-phrase''
as described in ''overflow-wrap: normal''
is insufficient to prevent overflow.
break-word
As for ''overflow-wrap/anywhere''
except that
soft wrap opportunities introduced by ''overflow-wrap/break-word''
are not considered
when calculating [=min-content size|min-content intrinsic sizes=].
overflow-wrap/overflow-wrap-001.html
overflow-wrap/overflow-wrap-break-word-001.html
overflow-wrap/overflow-wrap-break-word-003.html
overflow-wrap/overflow-wrap-break-word-008.html
overflow-wrap/overflow-wrap-break-word-009.html
overflow-wrap/overflow-wrap-break-word-010.html
overflow-wrap/overflow-wrap-min-content-size-004.html
overflow-wrap/overflow-wrap-min-content-size-006.html
overflow-wrap/overflow-wrap-min-content-size-008.html
overflow-wrap/overflow-wrap-break-word-fit-content-001.html
overflow-wrap/overflow-wrap-cluster-001.html
overflow-wrap/overflow-wrap-shaping-001.html
white-space/break-spaces-before-first-char-008.html
white-space/break-spaces-before-first-char-012.html
white-space/break-spaces-before-first-ideographic-char-008.html
white-space/break-spaces-before-first-ideographic-char-012.html
overflow-wrap/overflow-wrap-break-word-keep-all-001.html
white-space/break-spaces-with-overflow-wrap-001.html
white-space/break-spaces-with-overflow-wrap-003.html
white-space/break-spaces-with-overflow-wrap-005.html
white-space/break-spaces-with-overflow-wrap-007.html
white-space/break-spaces-with-overflow-wrap-009.html
white-space/trailing-ideographic-space-013.html
white-space/trailing-ideographic-space-014.html
white-space/trailing-ideographic-space-015.html
white-space/trailing-ideographic-space-016.html
white-space/text-wrap-balance-overflow-001.html
Issue: Do we need to add a none value to 'overflow-wrap'
to opt out of relaxing the ''keep-all'' and ''word-break/auto-phrase'' restrictions
as allowed by ''overflow-wrap: normal''?
For legacy reasons, UAs must treat 'word-wrap'
as a [=legacy name alias=] of the 'overflow-wrap' property.
overflow-wrap/word-wrap-alias.html
overflow-wrap/word-wrap-001.html
overflow-wrap/word-wrap-002.html
overflow-wrap/word-wrap-004.html
Alignment and Justification
Alignment and justification controls
how inline content is distributed within a line box.
Text Alignment: the 'text-align' shorthand
Name: text-align
Value: start | end | left | right | center | <> | justify | match-parent | justify-all
Initial: start
Applies to: block containers
Inherited: yes
Canonical order: n/a
Animation type: discrete
inheritance.html
parsing/text-align-valid.html
parsing/text-align-invalid.html
parsing/text-align-computed.html
text-align/text-align-webkit-match-parent.html
c546-txt-align-000.xht
text-align-005.xht
text-align-applies-to-001.xht
text-align-applies-to-002.xht
text-align-applies-to-003.xht
text-align-applies-to-005.xht
text-align-applies-to-006.xht
text-align-applies-to-007.xht
text-align-applies-to-008.xht
text-align-applies-to-009.xht
text-align-applies-to-010.xht
text-align-applies-to-011.xht
text-align-applies-to-012.xht
text-align-applies-to-013.xht
text-align-applies-to-014.xht
text-align-applies-to-015.xht
text-align-inherit-001.xht
text-align-bidi-011.xht
This [=shorthand property=]
sets the 'text-align-all' and 'text-align-last' properties
and describes how the inline-level content of a block
is aligned along the inline axis
if the content does not completely fill the line box.
Values other than ''justify-all'' or ''match-parent'' are assigned to 'text-align-all'
and reset 'text-align-last' to ''text-align-last/auto''.
Values have the following meanings:
start
Inline-level content is aligned
to the start edge of the line box.
text-align/text-align-006.html
text-align/text-align-start-001.html
text-align/text-align-start-002.html
text-align/text-align-start-003.html
text-align/text-align-start-004.html
text-align/text-align-start-005.html
text-align/text-align-start-006.html
text-align/text-align-start-007.html
text-align/text-align-start-008.html
text-align/text-align-start-009.html
text-align/text-align-start-010.html
text-align/text-align-start-014.html
text-align/text-align-start-015.html
text-align/text-align-start-016.html
text-align/text-align-start-017.html
text-align/text-align-start-018.html
text-align/text-align-start-019.html
text-align/text-align-start-020.html
text-align/text-align-start-021.html
end
Inline-level content is aligned
to the end edge of the line box.
text-align/text-align-007.html
text-align/text-align-end-001.html
text-align/text-align-end-002.html
text-align/text-align-end-003.html
text-align/text-align-end-004.html
text-align/text-align-end-005.html
text-align/text-align-end-006.html
text-align/text-align-end-007.html
text-align/text-align-end-008.html
text-align/text-align-end-009.html
text-align/text-align-end-010.html
text-align/text-align-end-014.html
text-align/text-align-end-015.html
text-align/text-align-end-016.html
text-align/text-align-end-017.html
text-align/text-align-end-018.html
text-align/text-align-end-019.html
text-align/text-align-end-020.html
text-align/text-align-end-021.html
left
Inline-level content is aligned
to the [=line-left=] edge of the line box.
(In vertical writing modes,
this can be either the physical top or bottom,
depending on 'writing-mode'.)
[[CSS-WRITING-MODES-4]]
text-align-001.xht
text-align-bidi-001.xht
text-align-bidi-006.xht
text-align-bidi-007.xht
right
Inline-level content is aligned
to the [=line-right=]
edge of the line box.
(In vertical writing modes,
this can be either the physical top or bottom,
depending on 'writing-mode'.)
[[CSS-WRITING-MODES-4]]
text-align-002.xht
text-align-bidi-005.xht
center
Inline-level content is centered within the line box.
text-align-003.xht
text-align-bidi-002.xht
text-align-bidi-003.xht
text-align-bidi-004.xht
text-align-inherit-001.xht
text-align/text-align-center-last-center.html
<>
The string must be a single character;
otherwise the declaration is invalid and must be
ignored.
When applied to a table cell, specifies the alignment character
around which the cell's contents will align.
See below for further details
and how this value combines with keywords.
justify
Text is justified
according to the method specified by the 'text-justify' property,
in order to exactly fill the line box.
Unless otherwise specified by 'text-align-last',
the last line before a forced break
or the end of the block
is ''text-align/start''-aligned.
text-align/text-align-justify-001.html
text-align/text-align-justify-002.html
text-align/text-align-justify-003.html
text-align/text-align-justify-004.html
text-align/text-align-justify-005.html
text-align/text-align-justify-006.html
text-align/text-align-justify-shy-001.html
text-align/text-align-justify-bidi-control.html
letter-spacing-justify-001.xht
text-align-004.xht
text-align-bidi-008.xht
text-align-bidi-009.xht
text-align-bidi-010.xht
text-align-bidi-012.xht
text-align-bidi-013.xht
text-align-white-space-002.xht
text-align-white-space-004.xht
text-align-white-space-006.xht
text-align-white-space-008.xht
word-spacing-justify-001.xht
justify-all
Sets both 'text-align-all'
and 'text-align-last'
to ''text-align/justify'',
forcing the last line to justify as well.
text-align/text-align-justifyall-001.html
text-align/text-align-justifyall-002.html
text-align/text-align-justifyall-003.html
text-align/text-align-justifyall-004.html
text-align/text-align-justifyall-005.html
text-align/text-align-justifyall-006.html
letter-spacing/letter-spacing-bidi-003.xht
match-parent
This value behaves the same as ''inherit''
(computes to its parent’s computed value)
except that an [=inherited value=] of
''text-align/start'' or ''text-align/end''
is interpreted against the parent’s
'direction' value
and results in a computed value of either
''text-align/left'' or ''text-align/right''.
Computes to ''text-align/start''
when specified on the [=root element=].
text-align/text-align-match-parent-001.html
text-align/text-align-match-parent-002.html
text-align/text-align-match-parent-01.html
text-align/text-align-match-parent-02.html
text-align/text-align-match-parent-03.html
text-align/text-align-match-parent-04.html
text-align/text-align-match-parent-root-ltr.html
text-align/text-align-match-parent-root-rtl.html
text-align/text-align-match-parent-root-logical.html
When specified on the 'text-align' shorthand,
sets both 'text-align-all' and 'text-align-last' to ''text-align/match-parent''.
text-align/text-align-match-parent-05.html
A block of text
is a stack of [=line boxes=].
This property specifies how the inline-level boxes within each line box
align with respect to the start and end sides of the line box.
Alignment is not with respect to the
[[CSS2/visuren#viewport|viewport]]
or containing block.
In the case of ''justify'',
the UA may stretch or shrink any inline boxes
by [[#text-justify-property|adjusting]] their text.
(See 'text-justify'.)
If an element’s [=white space=] is not [=collapsible=],
then the UA is not required to adjust its text
for the purpose of justification
and may instead treat the text
as having no [=justification opportunities=].
If the UA chooses to adjust the text,
then it must ensure
that tab stops continue to line up as required by the
[[#white-space-rules|white space processing rules]].
text-align-white-space-001.xht
text-align-white-space-005.xht
text-align/text-align-justify-tabs-001.html
text-align/text-align-justify-tabs-002.html
text-align/text-align-justify-tabs-003.html
text-align/text-align-justify-tabs-004.html
If (after justification, if any)
the inline contents of a line box are too long to fit within it,
then the contents are start-aligned:
any content that doesn’t fit
overflows the line box’s end edge.
See [[#bidi-linebox]] for details on how to determine
the start and end edges
of a line box.
Character-based Alignment in a Table Column
When multiple cells in a column have an alignment character specified,
the alignment character of each such cell in the column
is centered along a single column-parallel axis
and the rest of the text in the column shifted accordingly.
(Note that the strings do not have to be the same for each cell,
although they usually are.)
Is this intended to say that it's the centers
of the alignment characters that should be aligned?
It's not clear that's what it says,
but that (or a different behavior) needs to be specified,
to describe what happens
when different occurrences of the alignment character
are in different fonts.
(Further, is that the intended behavior? Probably the most
significant use case to consider is bold vs. non-bold text,
which only varies slightly in width.)
[feedback]
[minutes face-to-face 2016-02-02 10:00 AM]
The following style sheet:
TD { text-align: "." center }
will cause the column of dollar figures in the following HTML table:
A keyword value may be specified in conjunction with the <> value;
if it is not given, it defaults to ''text-align/right''.
This value is used:
when character-based alignment is applied
to boxes that are not table cells.
when the text wraps to multiple lines (at unforced break points).
when a character-aligned cell spans more than one column.
In this case the keyword alignment value is used
to determine which column's axis to align with:
the leftmost column for ''text-align/left'',
the rightmost column for ''text-align/right'' and ''text-align/center'',
the startmost column for ''text-align/start'',
the endmost column for ''text-align/end''.
when the column is wide enough that the character alignment alone
does not determine the positions of its character-aligned contents.
In this case the keyword alignment of the first cell in the column
with a specified alignment character
is used to slide the position of the character-aligned contents
to match the keyword alignment
insofar as possible without changing the width of the column.
For ''text-align/center'',
the UA may center the aligned contents using its extremes,
center the alignment axis itself (insofar as possible),
or optically center the aligned contents some other way
(such as by taking a weighted average
of the extent of the cells' contents to either side of the axis).
Note: Right alignment is used by default for character-based alignment
because numbering systems are almost all left-to-right
even in right-to-left writing systems,
and the primary use case of character-based alignment
is for numerical alignment.
If the alignment character appears more than once in the text,
the first instance is used for alignment.
If the alignment character does not appear in a cell at all,
the string is aligned as if
the alignment character had been inserted at the end of its contents.
This needs to specify what text is searched
for the alignment character.
Is it only in-flow text whose containing block is the cell?
Or is text within any in-flow descendants
in the block formatting context established by the cell considered?
If so, is it considered only as long as its 'text-align' property
is consistent with the cell's?
(Consistent in the alignment character, or fully consistent?)
This behavior of aligning as though the alignment character
had been inserted at the end of the contents of the cell,
combined with center-of-character alignment,
will produce gaps on the end-side of lines
that are alone on a line with <> text-alignment,
when none of the lines of the column has the alignment character,
or, more importantly, when some of the lines
do have the alignment character,
but the column is not laid out at its max-content width.
This is probably undesirable.
When the alignment character is inserted
at the end of the contents,
which font is used?
(In particular, if the alignment character might be within a descendant block,
is it the font of the block or the font of the table cell?
Or if the insertion is at a forced break within an inline,
does it use the font of the inline or the font of the block or cell?)
Character-based alignment occurs before table cell width computation
so that auto width computations can leave enough space for alignment.
Whether column-spanning cells participate in the alignment
prior to or after width computation is undefined.
If width constraints on the cell contents prevent
full alignment throughout the column,
the resulting alignment is undefined.
This should have a formal definition
of how character alignment affects
the min-content and max-content intrinsic widths
(of table columns and all content that can be inside table columns).
Max-content intrinsic widths need to be split
into three numbers (assuming that it's the centers of the
alignment character that are aligned):
one for widths without alignment characters,
one for widths on the inline-start side
of the center of the alignment character,
one for widths on the inline-end side
of the center of the alignment character.
This operates based on all segments of text
between forced breaks for max-content widths.
For min-content widths, segments of text between forced breaks
that contain optional breaks within them should clearly contribute
only to the without-alignment-character width.
However, it's less clear
whether all min-content widths should work this way,
or whether segments between forced breaks
that do not have optional breaks
(and perhaps only those that actually contain the alignment character)
should contribute to start-side-of-alignment-character
and end-side-of-alignment-character min-content widths instead;
this choice is a tradeoff between the meaning of min-content
sizing of a table meaning the narrowest reasonable size versus
honoring alignment characters in more cases.
Another option might be to use whether line-breaking of optional breaks
is allowed as a control for which behavior to use.
Formally defining the intrinsic width contributions
of column-spanning cells with <> values of
'text-align' is a complicated (although straightforward) extension
of the decisions made for intrinsic width contributions
of non-column-spanning cells;
this should also be formally defined.
Contributions end up being made to the split intrinsic widths
of the startmost or endmost column (whichever is used for alignment),
and to the without-alignment-character intrinsic widths
of the other spanned columns.
Default Text Alignment: the 'text-align-all' property
Name: text-align-all
Value: start | end | left | right | center | <> | justify | match-parent
Initial: start
Applies to: block containers
Inherited: yes
Computed value: keyword as specified, except for ''match-parent'' which computes as defined above
Canonical order: n/a
Animation type: discrete
inheritance.html
parsing/text-align-all-valid.html
parsing/text-align-all-invalid.html
This longhand of the 'text-align' [=shorthand property=]
specifies the inline alignment of all lines of inline content in the block container,
except for last lines
overridden by a non-''text-align-last/auto'' value of 'text-align-last'.
See 'text-align' for a full description of values.
Authors should use the 'text-align' shorthand instead of this property.
Last Line Alignment: the 'text-align-last' property
Name: text-align-last
Value: auto | start | end | left | right | center | justify | match-parent
Initial: auto
Applies to: block containers
Inherited: yes
Canonical order: n/a
Computed value: keyword as specified, except for ''match-parent'' which computes as defined above
Animation type: discrete
inheritance.html
parsing/text-align-last-valid.html
parsing/text-align-last-invalid.html
parsing/text-align-last-computed.html
text-align/text-align-last-013.html
text-align/text-align-last-014.html
text-align/text-align-last-justify-br.html
This property describes how the last line of a block or a line
right before a [=forced line break=]
is aligned.
text-align/text-align-last-001.html
text-align/text-align-last-002.html
text-align/text-align-last-003.html
text-align/text-align-last-004.html
text-align/text-align-last-005.html
text-align/text-align-last-006.html
text-align/text-align-last-010.html
text-align/text-align-last-011.html
text-align/text-align-last-012.html
text-align/text-align-last-wins-001.html
If auto is specified,
content on the affected line is aligned per 'text-align-all'
unless 'text-align-all' is set to ''justify'',
in which case it is ''text-align/start''-aligned.
All other values are interpreted as described for 'text-align'.
text-align/text-align-last-007.html
text-align/text-align-last-008.html
text-align/text-align-last-009.html
text-align/text-align-center-last-center.html
text-align/text-align-center-last-default.html
text-align/text-align-center-last-end.html
text-align/text-align-center-last-justify.html
text-align/text-align-center-last-start.html
text-align/text-align-default-last-default.html
text-align/text-align-end-last-center.html
text-align/text-align-end-last-default.html
text-align/text-align-end-last-end.html
text-align/text-align-end-last-justify.html
text-align/text-align-end-last-start.html
text-align/text-align-inline-end-crash.html
text-align/text-align-justify-last-center.html
text-align/text-align-justify-last-default.html
text-align/text-align-justify-last-end.html
text-align/text-align-justify-last-justify.html
text-align/text-align-justify-last-start.html
text-align/text-align-last-center.html
text-align/text-align-last-end.html
text-align/text-align-last-interpolation.html
text-align/text-align-last-justify-rtl.html
text-align/text-align-last-justify.html
text-align/text-align-last-simple.html
text-align/text-align-last-start.html
text-align/text-align-start-last-center.html
text-align/text-align-start-last-default.html
text-align/text-align-start-last-end.html
text-align/text-align-start-last-justify.html
text-align/text-align-start-last-start.html
text-align/text-align-match-parent-05.html
text-align/text-align-last-015.html
Justification Method: the 'text-justify' property
Name: text-justify
Value: [ auto | none | inter-word | inter-character | ruby ] || no-compress
Initial: auto
Applies to: text
Inherited: yes
Canonical order: n/a
Computed value: specified keyword (except for the ''distribute'' legacy value)
Animation type: discrete
inheritance.html
parsing/text-justify-valid.html
parsing/text-justify-invalid.html
parsing/text-justify-computed.html
text-justify/text-justify-006.html
text-justify/text-justify-interpolation.html
This property selects the justification method
used when a line’s alignment is set to ''justify''
(see 'text-align').
The property applies to text,
but is inherited from block containers
to the root inline box containing their inline-level contents.
It takes the following values:
text-justify/text-justify-006.html
auto
The UA determines the justification algorithm to follow,
based on a balance between performance and adequate presentation quality.
Since justification rules vary by [=writing system=]
and [=content language|language=],
UAs should, where possible,
use a justification algorithm appropriate to the text.
text/letter-spacing-justify-001.xht
text/word-spacing-justify-001.xht
For example,
the UA could use by default a justification method
that is a simple universal compromise for all writing systems--
such as primarily expanding [=word separators=]
and between CJK [=typographic letter units=]
along with secondarily expanding
between Southeast Asian [=typographic letter units=].
Then, in cases where the [=content language=] of the paragraph is known,
it could choose a more language-tailored justification behavior
e.g. following the Requirements for Japanese Text Layout for Japanese [[JLREQ]],
using cursive elongation for Arabic,
using ''inter-word'' for German,
etc.
An example of cursively-justified Arabic text,
rendered by Tasmeem.
Like English,
Arabic can be justified by adjusting the spacing between words,
but in most styles
it can also be justified by calligraphically elongating
or compressing the letterforms themselves.
In this example,
the upper text is extended to fill the line
by the use of elongated (kashida) forms and swash forms,
while the bottom line is compressed slightly
by using a stacked combination for the characters between ت and م.
By employing traditional calligraphic techniques,
a typesetter can justify the line while preserving flow and color,
providing a very high quality justification effect.
However, this is by its nature a very script-specific effect.
Mixed-script text with ''text-justify: auto'':
this interpretation uses a universal-compromise justification method,
expanding at spaces as well as between CJK and Southeast Asian letters.
This effectively uses inter-word + inter-ideograph spacing
for lines that have word-separators and/or CJK characters
and falls back to inter-cluster behavior for lines that don’t
or for which the space stretches too far.
none
Justification is disabled:
there are no [=justification opportunities=] within the text.
text-justify/text-justify-001.html
text-justify/text-justify-006.html
text-justify-none-001.html
Mixed-script text with ''text-justify: none''
Note: This value is intended for use in user stylesheets
to improve readability or for accessibility purposes.
inter-word
Justification adjusts spacing at [=word separators=] only
(effectively varying the used 'word-spacing' on the line).
This behavior is typical for languages that separate words using spaces,
like English or Korean.
text-justify-inter-word-001.html
text-justify-word-separators.html
Mixed-script text with ''text-justify: inter-word''
inter-character
Justification adjusts spacing
between each pair of adjacent [=typographic character units=]
(effectively varying the used 'letter-spacing' on the line).
This value is sometimes used in East Asian systems such as Japanese.
text-justify/text-justify-002.html
text-justify-inter-character-001.html
Mixed-script text with ''text-justify: inter-character''
For legacy reasons,
UAs must also support the alternate keyword distribute
which must compute to ''inter-character'',
thus having the exact same meaning and behavior.
UAs may treat this as a [=legacy value alias=].
text-justify/text-justify-003.html
parsing/text-justify-computed-legacy.html
text-justify/text-justify-distribute-001.html
ruby
Justification adjusts spacing as for ''text-justify/auto'' except:
* [=Justification opportunities=] are disabled at [=word separators=].
* [=Justification opportunities=] are disabled between [=Bopomofo characters=]
Note: This value is intended for use in [=ruby annotations=],
providing a reasonable default alignment.
See [[CSS-RUBY-1]].
no-compress
Justification must not compress spacing controlled by
'text-spacing-trim' or 'text-autospace'.
(If this value is not specified,
the justification process may reduce such spacing
except when the spacing is at the start or end of the line.)
Note: An example of compression rules is given for Japanese
in 3.8 Line Adjustment in [[JLREQ]].
Issue(7079): This keyword used to be part of 'text-spacing';
it might need renaming to be more specific now that it's here,
as it implies that e.g. U+0020 cannot be compressed.
Since optimal justification is [=content language|language=]-sensitive,
authors should correctly language-tag their content for the best results.
Note: The guidelines in this level of CSS
do not describe a complete justification algorithm.
They are merely a minimum set of requirements
that a complete algorithm should meet.
Limiting the set of requirements gives UAs some latitude
in choosing a justification algorithm
that meets their needs and desired balance of quality, speed, and complexity.
Expanding and Compressing Text
When justifying text,
the user agent takes the remaining space
between the ends of a line’s contents and the edges of its line box,
and distributes that space throughout its content
so that the contents exactly fill the line box.
The user agent may alternatively distribute negative space,
putting more content on the line
than would otherwise fit under normal spacing conditions.
A justification opportunity is a point
where the justification algorithm may alter spacing within the text.
A justification opportunity can be provided by a single [=typographic character unit=]
(such as a [=word separator=]),
or by the juxtaposition of two [=typographic character units=].
As with controls for [[#line-break-details|soft wrap opportunities]],
whether a [=typographic character unit=] provides a [=justification opportunity=]
is controlled by the 'text-justify' value of its parent;
similarly,
whether a [=justification opportunity=] exists
between two consecutive [=typographic character units=]
is determined by the 'text-justify' value of their nearest common ancestor.
Space distributed by justification is in addition to
the spacing defined by the 'letter-spacing' or 'word-spacing' properties.
When such additional space is distributed
to a [=word separator=] [=justification opportunity=],
it is applied under the same rules as for 'word-spacing'.
Similarly, when space is distributed
to a [=justification opportunity=] between two [=typographic character units=],
should be applied under the same rules as for 'letter-spacing'.
A justification algorithm may divide [=justification opportunities=]
into different priority levels.
All [=justification opportunities=] within a given level
are expanded or compressed at the same priority,
regardless of which [=typographic character units=] created that opportunity.
For example,
if [=justification opportunities=] between two Han characters
and between two Latin letters
are defined to be at the same level
(as they are in the ''inter-character'' justification style),
they are not treated differently
because they originate from different [=typographic character units=].
It is not defined in this level
whether or how other factors
(such as font size, letter-spacing, glyph shape, position within the line, etc.)
may influence the distribution of space to [=justification opportunities=] within the line.
The UA may enable or break optional ligatures
or use other font features
such as alternate glyphs or glyph compression
to help justify the text under any method.
This behavior is not controlled by this level of CSS.
However,
UAs must not break required ligatures
or otherwise disable features required to correctly shape complex scripts.
If a [=justification opportunity=] exists within a line,
and [[#text-align-property|text alignment]] specifies full justification
(''text-align/justify'')
for that line,
it must be justified.
Handling Symbols and Punctuation
When determining [=justification opportunities=],
a [=typographic character unit=]
from the Unicode Symbols (S*) and Punctuation (P*) classes
is generally treated the same as a [=typographic letter unit=] of the same script
(or, if the character’s script property is Common,
then as a [=typographic letter unit=] of the dominant script).
However, by typographic tradition
there may be additional rules controlling the justification of symbols and punctuation.
Therefore, the UA may reassign specific characters
or introduce additional levels of prioritization
to handle [=justification opportunities=] involving symbols and punctuation.
For example, there are traditionally no [=justification opportunities=]
between consecutive
U+2014 — EM DASH,
U+2015 ― HORIZONTAL BAR,
U+2026 … HORIZONTAL ELLIPSIS,
or U+2025 ‥ TWO DOT LEADER
characters [[JLREQ]];
thus a UA might assign these characters to a “never” prioritization level.
As another example, certain full-width punctuation characters
(such as U+301A 〚 LEFT WHITE SQUARE BRACKET)
are considered to contain a [=justification opportunity=] in Japanese.
The UA might therefore assign these characters to a higher prioritization
level than the opportunities between ideographic characters.
Unexpandable Text
If the inline contents of a line cannot be stretched to the full width of the line box,
then they must be aligned as specified by the 'text-align-last' property.
(If 'text-align-last' is ''justify'',
then they must be aligned as for ''text-align/center''.)
text-align/text-align-last-empty-inline.html
Cursive Scripts
Justification must not introduce gaps
between the joined [=typographic letter units=]
of [=cursive scripts=] such as Arabic.
If it is able,
the UA may translate space distributed to [=justification opportunities=]
within a run of such [=typographic letter units=]
into some form of cursive elongation for that run.
It otherwise must assume that no [=justification opportunity=] exists
between any pair of [=typographic letter units=] in [=cursive script=]
(regardless of whether they join).
text-justify/text-justify-004.html
text-justify/text-justify-005.html
The following are examples of unacceptable justification:
Adding gaps between every pair of Arabic letters
Adding gaps between every pair of unjoined Arabic letters
Some font designs allow for the use of the tatweel character for justification.
A UA that performs tatweel-based justification
must properly handle the rules for its use.
Note that correct insertion of tatweel characters depends on context,
including the letter-combinations involved,
location within the word,
and location of the word within the line.
Minimum Requirements for ''text-justify/auto'' Justification
For ''text-justify/auto'' justification,
this specification does not define
what all of the [=justification opportunities=] are,
how they are prioritized,
or when and how multiple levels of [=justification opportunities=] interact.
However, it does require that:
Unless contraindicated by the typographic traditions
of the [=content language=]
or adjacent symbols/punctuation,
each of the following provides a [=justification opportunity=]:
[=Word separators=]
The boundary between a [=typographic character unit=]
of any [=block scripts=]
and any other [=typographic character unit=]
The boundary between a [=typographic character unit=]
of any [=clustered scripts=]
and any other [=typographic character unit=]
All [=letters=] belonging to all [=block scripts=] are treated the same,
and all [=letters=] belonging to all [=clustered scripts=] are treated the same.
For example, no distinction is made
between the justification opportunity
between a Han letter followed by another Han letter,
vs. the justification opportunity
between a Han letter followed by a Hangul letter.
Aligning a block of text within its container: the 'text-group-align' property
Name: text-group-align
Value: none | start | end | left | right | center
Initial: none
Applies to: block containers
Inherited: no
Percentages: N/A
Computed value: specified keyword
Animation type: discrete
parsing/text-group-align-invalid.html
parsing/text-group-align-valid.html
This property aligns the contents of the line boxes as a group
while maintaining their text alignment.
Group alignment
is performed by finding the line box with the shortest remaining space
and adding that amount of space as padding to one or both sides of the line box,
reducing the amount of space available for its contents;
text alignment is then applied
to its contents within the remaining space.
All descendant [=in-flow=] line boxes within the same [=block formatting context=]
are considered
both when searching for the shortest remaining space
and when adding the padding;
the contents of descendants that establish [=independent formatting contexts=]
are skipped.
text-group-align/text-group-align-center-vlr.html
text-group-align/text-group-align-center.html
text-group-align/text-group-align-end-vlr.html
text-group-align/text-group-align-end.html
text-group-align/text-group-align-left-vlr.html
text-group-align/text-group-align-left.html
text-group-align/text-group-align-right-vlr.html
text-group-align/text-group-align-right.html
text-group-align/text-group-align-start-vlr.html
text-group-align/text-group-align-start.html
Issue: A variant of this property is inherited,
and applies on each block container individually,
only affecting the line boxes that are direct children of that block.
This is less useful, but probably easier to implement.
Issue: Somehow also moving the floats that originate in the same block container
by the same amount
would make things line up more nicely,
which would be especially valuable in CJK layout.
Exactly how that works, and how it interacts with intruding floats
from ancestor elements is left as an exercise for the reader.
Values have the following meanings:
none
Text alignment happens normally: [=group alignment=] is not performed.
start
Inline-level content is [=group-aligned=] to the [=inline start=] side,
by padding the [=inline end=] side of each line box.
text-group-align/text-group-align-start-vlr.html
text-group-align/text-group-align-start.html
end
Inline-level content is [=group-aligned=] to the [=inline end=] side,
by padding the [=inline start=] side of each line box.
text-group-align/text-group-align-end-vlr.html
text-group-align/text-group-align-end.html
left
Inline-level content is [=group-aligned=] to the [=line-left=] side,
by padding the [=line-right=] side of each line box.
text-group-align/text-group-align-left-vlr.html
text-group-align/text-group-align-left.html
right
Inline-level content is [=group-aligned=] to the [=line-right=] side,
by padding the [=line-left=] side of each line box.
text-group-align/text-group-align-right-vlr.html
text-group-align/text-group-align-right.html
center
Inline-level content is [=group-aligned=] to the center,
by padding both sides of each line box,
half the spacing to each side.
text-group-align/text-group-align-center-vlr.html
text-group-align/text-group-align-center.html
Spacing
CSS offers control over regular text spacing
via the 'word-spacing', 'letter-spacing', and 'line-padding' properties,
which specify additional space
around [=word separators=]
between [=typographic character units=],
or at the start/end of the line,
respectively.
It also provides contextual control over spacing
via the 'text-spacing-trim' property,
which allows for contextual fullwidth vs halfwidth setting of CJK punctuation;
and the 'text-autospace' property,
which allows automatic insertion of extra space
at script changes or around punctuation.
Word Spacing: the 'word-spacing' property
Name: word-spacing
Value: normal | <>
Initial: normal
Applies to: text
Inherited: yes
Percentages: relative to computed 'font-size', i.e. ''1em''
Computed value: an absolute length and/or a percentage
Animation type: by computed value type
Canonical order: n/a
inheritance.html
parsing/word-spacing-valid.html
parsing/word-spacing-invalid.html
parsing/word-spacing-computed.html
animations/word-spacing-interpolation.html
animations/word-spacing-composition.html
c541-word-sp-000.xht
c541-word-sp-001.xht
word-spacing-101.xht
word-spacing-applies-to-001.xht
word-spacing-applies-to-002.xht
word-spacing-applies-to-003.xht
word-spacing-applies-to-005.xht
word-spacing-applies-to-006.xht
word-spacing-applies-to-007.xht
word-spacing-applies-to-008.xht
word-spacing-applies-to-009.xht
word-spacing-applies-to-010.xht
word-spacing-applies-to-011.xht
word-spacing-applies-to-012.xht
word-spacing-applies-to-013.xht
word-spacing-applies-to-014.xht
word-spacing-applies-to-015.xht
word-spacing-justify-001.xht
This property specifies additional spacing
between “words”.
Values are interpreted as defined below:
normal
No additional spacing is applied.
Computes to zero.
word-spacing-100.xht
word-spacing/word-spacing-computed-001.html
<length-percentage>
Specifies extra spacing
in addition to the intrinsic inter-word spacing
defined by the font.
word-spacing/word-spacing-001.html
word-spacing/word-spacing-002.html
word-spacing/word-spacing-percent-001.html
tab-size/tab-size-spacing-001.html
Note: Percentages inherit intact,
and are resolved against
the computed 'font-size' of the current element
(and thus represent a size relative to
the size of the text to which they apply),
unlike ''em'' units which are resolved against
the computed 'font-size' of the element from which they inherit,
as an absolute length.
word-spacing-004.xht
word-spacing-005.xht
word-spacing-006.xht
word-spacing-007.xht
word-spacing-008.xht
word-spacing-016.xht
word-spacing-017.xht
word-spacing-018.xht
word-spacing-019.xht
word-spacing-020.xht
word-spacing-028.xht
word-spacing-029.xht
word-spacing-030.xht
word-spacing-031.xht
word-spacing-032.xht
word-spacing-040.xht
word-spacing-041.xht
word-spacing-042.xht
word-spacing-043.xht
word-spacing-044.xht
word-spacing-052.xht
word-spacing-053.xht
word-spacing-054.xht
word-spacing-055.xht
word-spacing-056.xht
word-spacing-064.xht
word-spacing-065.xht
word-spacing-066.xht
word-spacing-067.xht
word-spacing-068.xht
word-spacing-076.xht
word-spacing-077.xht
word-spacing-078.xht
word-spacing-079.xht
word-spacing-080.xht
word-spacing-088.xht
word-spacing-089.xht
word-spacing-090.xht
word-spacing-091.xht
word-spacing-092.xht
word-spacing-097.xht
word-spacing-098.xht
word-spacing-099.xht
Additional spacing is applied to each [=word separator=] left in the text
after the [[#white-space-rules|white space processing rules]] have been applied,
and should be applied half on each side of the character
unless otherwise dictated by typographic tradition.
Values may be negative, but there may be implementation-dependent limits.
word-spacing-remove-space-001.xht
word-spacing-remove-space-002.xht
word-spacing-remove-space-003.xht
word-spacing-remove-space-004.xht
word-spacing-remove-space-005.xht
word-spacing-remove-space-006.xht
word-spacing/word-spacing-negative-value-001.html
Word-separator characters
are [=typographic character units=]
whose primary purpose and general usage is to separate words.
In Unicode this includes
(but is not exhaustively defined as)
the space (U+0020),
the no-break space (U+00A0),
the Ethiopic word space (U+1361),
the Aegean word separators (U+10100,U+10101),
the Ugaritic word divider (U+1039F),
and the Phoenician word separator (U+1091F).
[[UNICODE]]
word-spacing-characters-001.xht
Note: Neither punctuation in general,
nor fixed-width spaces (such as U+3000 and U+2000 through U+200A),
are considered [=word-separator characters=],
because even though they frequently happen to separate words,
their primary purpose is not to separate words.
word-spacing-characters-002.xht
If there are no [=word-separator characters=],
or if a word-separating character has a zero advance width
(such as U+200B ZERO WIDTH SPACE)
then the user agent must not create an additional spacing between words.
word-spacing-characters-003.xht
Tracking: the 'letter-spacing' property
Name: letter-spacing
Value: normal | <>
Initial: normal
Applies to: inline boxes and text
Inherited: yes
Percentages: relative to computed 'font-size', i.e. ''1em''
Computed value: an absolute length and/or a percentage
Animation type: by computed value type
Canonical order: n/a
inheritance.html
parsing/letter-spacing-valid.html
parsing/letter-spacing-invalid.html
parsing/letter-spacing-computed.html
animations/letter-spacing-interpolation.html
animations/letter-spacing-composition.html
letter-spacing/letter-spacing-nesting-003.xht
letter-spacing/letter-spacing-bidi-003.xht
letter-spacing/letter-spacing-bidi-004.xht
letter-spacing/letter-spacing-bidi-005.xht
letter-spacing/letter-spacing-200.html
letter-spacing/letter-spacing-201.html
letter-spacing/letter-spacing-203.html
letter-spacing/letter-spacing-206.html
letter-spacing/letter-spacing-end-of-line-002.html
c542-letter-sp-000.xht
c542-letter-sp-001.xht
letter-spacing-applies-to-001.xht
letter-spacing-applies-to-002.xht
letter-spacing-applies-to-003.xht
letter-spacing-applies-to-005.xht
letter-spacing-applies-to-006.xht
letter-spacing-applies-to-007.xht
letter-spacing-applies-to-008.xht
letter-spacing-applies-to-009.xht
letter-spacing-applies-to-010.xht
letter-spacing-applies-to-011.xht
letter-spacing-applies-to-012.xht
letter-spacing-applies-to-013.xht
letter-spacing-applies-to-014.xht
letter-spacing-applies-to-015.xht
This property specifies additional spacing
(commonly called tracking)
between adjacent [=typographic character units=].
Letter-spacing is applied after
[[css-writing-modes-4#text-direction|bidi reordering]]
and is in addition to [[css-fonts-3#font-kerning-prop|kerning]]
and 'word-spacing'.
[[CSS-WRITING-MODES-4]]
[[CSS-FONTS-3]]
Depending on the justification rules in effect,
user agents may further increase or decrease the space
between [=typographic character units=]
in order to [[#text-justify-property|justify text]].
letter-spacing/letter-spacing-bidi-001.html
letter-spacing/letter-spacing-bidi-004.xht
letter-spacing/letter-spacing-nesting-003.xht
letter-spacing/letter-spacing-bidi-003.xht
letter-spacing/letter-spacing-bidi-004.xht
letter-spacing/letter-spacing-bidi-005.xht
letter-spacing/letter-spacing-206.html
letter-spacing/letter-spacing-211.html
letter-spacing/letter-spacing-212.html
letter-spacing/letter-spacing-bengali-yaphala-001.html
bidi-005.xht
bidi-006.xht
bidi-007.xht
bidi-008.xht
bidi-009.xht
bidi-010.xht
bidi-text/bidi-005a.xht
bidi-text/bidi-005b.xht
bidi-text/bidi-006a.xht
bidi-text/bidi-006b.xht
bidi-text/bidi-007b.xht
bidi-text/bidi-008b.xht
bidi-text/bidi-009b.xht
bidi-text/bidi-010b.xht
text/letter-spacing-justify-001.xht
Values have the following meanings:
normal
No additional spacing is applied. Computes to zero.
letter-spacing-100.xht
<length-percentage>
Specifies additional spacing
between [=typographic character units=].
Values may be negative,
but there may be implementation-dependent limits.
tab-size/tab-size-spacing-001.html
Note: Percentages inherit intact,
and are resolved against
the computed 'font-size' of the current element
(and thus represent a size relative to
the size of the text to which they apply),
unlike ''em'' units which are resolved against
the computed 'font-size' of the element from which they inherit,
as an absolute length.
letter-spacing-004.xht
letter-spacing-005.xht
letter-spacing-006.xht
letter-spacing-007.xht
letter-spacing-008.xht
letter-spacing-016.xht
letter-spacing-017.xht
letter-spacing-018.xht
letter-spacing-019.xht
letter-spacing-020.xht
letter-spacing-028.xht
letter-spacing-029.xht
letter-spacing-030.xht
letter-spacing-031.xht
letter-spacing-032.xht
letter-spacing-040.xht
letter-spacing-041.xht
letter-spacing-042.xht
letter-spacing-043.xht
letter-spacing-044.xht
letter-spacing-052.xht
letter-spacing-053.xht
letter-spacing-054.xht
letter-spacing-055.xht
letter-spacing-056.xht
letter-spacing-064.xht
letter-spacing-065.xht
letter-spacing-066.xht
letter-spacing-067.xht
letter-spacing-068.xht
letter-spacing-076.xht
letter-spacing-077.xht
letter-spacing-078.xht
letter-spacing-079.xht
letter-spacing-080.xht
letter-spacing-088.xht
letter-spacing-089.xht
letter-spacing-090.xht
letter-spacing-091.xht
letter-spacing-092.xht
letter-spacing-097.xht
letter-spacing-098.xht
letter-spacing-099.xht
letter-spacing-101.xht
letter-spacing-102.xht
letter-spacing/letter-spacing-percent-001.html
For legacy reasons,
a computed 'letter-spacing' of zero
yields a [=resolved value=]
({{getComputedStyle()}} return value)
of ''letter-spacing/normal''.
For the purpose of 'letter-spacing',
each consecutive run of [=atomic inlines=]
(such as images and inline blocks)
is treated as a single [=typographic character unit=].
letter-spacing/letter-spacing-204.html
Letter-spacing must not be applied at the beginning of a line.
Whether letter-spacing is applied at the end of a line is undefined in this level.
letter-spacing/letter-spacing-trim-start-001.html
letter-spacing/letter-spacing-trim-start-002.html
letter-spacing/letter-spacing-end-of-line-001.html
tab-size/tab-size-spacing-001.html
letter-spacing/letter-spacing-200.html
letter-spacing/letter-spacing-201.html
white-space/white-space-letter-spacing-001.html
When letter-spacing is not applied at the beginning or end of a line,
text always fits flush with the edge of the block.
p { letter-spacing: 1em; }
<p>abc</p>
a b c
a b c
UAs therefore really should not [[RFC6919]]
append letter spacing to the right or trailing edge of a line:
a b c
Letter spacing between two [=typographic character units=]
effectively “belongs” to the innermost element
that contains the two [=typographic character units=]:
the total letter spacing between two adjacent [=typographic character units=]
(after bidi reordering)
is specified by and rendered within the innermost element
that contains the boundary
between the two [=typographic character units=].
However, the UA may instead attach letter-spacing at element boundaries
to one or the other [=typographic character unit=]
using the letter-spacing value pertaining to its containing element.
Note: This secondary behavior is permitted in this level
due to Web-compat concerns.
letter-spacing/letter-spacing-bidi-002.html
letter-spacing/letter-spacing-bidi-004.xht
letter-spacing/letter-spacing-bidi-005.xht
letter-spacing/letter-spacing-nesting-001.html
letter-spacing/letter-spacing-nesting-002.html
letter-spacing/letter-spacing-nesting-003.xht
letter-spacing/letter-spacing-203.html
letter-spacing/letter-spacing-205.html
An inline box is expected to only include
letter spacing between characters completely contained within that element,
thus excluding letter spacing on the right or trailing edge of the element:
p { letter-spacing: 1em; }
<p>a<span>bb</span>c</p>
a b b c
a b b c
Consequently a given value of 'letter-spacing' is expected
to only affect the spacing between characters
completely contained within the element for which it is specified:
p { letter-spacing: 1em; }
span { letter-spacing: 2em; }
<p>a<span>bb</span>c</p>
a b b c
This further implies that applying 'letter-spacing' to
an element containing only a single character
has no effect on the rendered result:
p { letter-spacing: 1em; }
span { letter-spacing: 2em; }
<p>a<span>b</span>c</p>
a b c
Since letter spacing is inserted after RTL reordering,
the letter spacing applied to the inner span below likewise has no effect,
since after reordering the "c" doesn’t end up next to "א":
p { letter-spacing: 1em; }
span { letter-spacing: 2em; }
<!-- abc followed by Hebrew letters alef (א), bet (ב) and gimel (ג) -->
<!-- Reordering will display these in reverse order. -->
<p>ab<span>cא</span>בג</p>
a b cא ב ג
Letter spacing ignores invisible zero-width formatting characters
(such as those from the Unicode Cf category).
Spacing must be added as if those characters did not exist in the document.
letter-spacing/letter-spacing-control-chars-001.html
letter-spacing/letter-spacing-202.html
For example, 'letter-spacing' applied to
A​B is identical to AB,
regardless of where any element boundaries might fall.
When the effective spacing between two characters is not zero
(due to either [[#text-justify-property|justification]]
or a non-zero value of 'letter-spacing'),
user agents should not apply optional ligatures,
i.e. those that are not defined as required
for fundamentally correct glyph shaping.
However, ligatures and other font features
specified via the low-level 'font-feature-settings' property
take precedence over this rule.
See [[css-fonts-3#feature-precedence]].
letter-spacing/letter-spacing-ligatures-001.html
letter-spacing/letter-spacing-ligatures-002.html
letter-spacing/letter-spacing-ligatures-003.html
letter-spacing/letter-spacing-ligatures-004.html
For example, if the word “filial” is letter-spaced,
an “fi” ligature should not be used
as it will prevent even spacing of the text.
filial vs filial
Note: In OpenType, required ligatures are expected
to be associated to the rlig feature.
All other ligatures are therefore considered optional.
In some cases, however, UA or platform heuristics
apply additional ligatures in order to handle broken fonts;
this specification does not define or override such exceptional handling.
Cursive Scripts
If it is able,
the UA may apply letter spacing to [=cursive scripts=]
by translating the total extra space to be distributed to a run of such letters
into some form of cursive elongation
(or compression, for negative tracking values)
for that run
that results in an equivalent total expansion (or compression) of the run.
Otherwise,
if the UA cannot expand text from a [=cursive script=]
without breaking its cursive connections,
it must not apply spacing
between any pair of that script’s [=typographic letter units=] at all
(effectively treating each word as a single [=typographic letter unit=]
for the purpose of letter-spacing).
Both cases will result in an effective spacing of zero between such letters;
however the former will preserve the sense of stretching out the text.
Below are some appropriate and inappropriate examples of spacing out Arabic text.
—
Original text
BAD
Even distribution of space between each letter.
Notice this breaks cursive joins!
OK
Distributing ∑letter-spacing
by typographically-appropriate cursive elongation.
The resulting text is as long as the previous evenly-spaced example.
OK
Suppressing 'letter-spacing' between Arabic letters.
Notice 'letter-spacing' is nonetheless applied
to non-Arabic characters (like [=spaces=]).
BAD
Applying 'letter-spacing' only between non-joined letters.
This distorts typographic color and obfuscates word boundaries.
Note: Proper cursive elongation or compression of a text
can vary depending on the
script,
typeface,
language,
location within a word,
location within a line,
implementation complexity,
font capabilities,
and calligraphic preferences,
and may not be possible in certain cases at all.
It may involve the use of shortening ligatures,
swash variants,
contextual forms,
elongation glyphs such as U+0640 ـ ARABIC TATWEEL,
or other microtypography.
It is outside the scope of CSS to define rules for these effects.
Authors should avoid applying 'letter-spacing' to cursive scripts
unless they are prepared to accept non-interoperable results.
Line Start/End Padding: the 'line-padding' property
Name: line-padding
Value: <>
Initial: 0
Applies to: inline boxes
Inherited: yes
Percentages: N/A
Computed value: absolute length
Animation type: by computed value type
Whereas 'letter-spacing' adjusts spacing
between typographic character units
and does not apply at the start or end of a line,
this property adjusts spacing only at the start/end of a line.
The extra spacing is applied only
by the innermostinline box
at the start/end of the line box,
and is inserted between that inline box’s content edge
and the adjacent inline-level content
([=text sequence|text=] oratomic inline).
This extra space is not a justification opportunity.
Given the following HTML and CSS:
p { line-padding: 0.5em; line-height: 1; text-align: center }
span { background: black; color: white; }
em { background: green; color: white; }
<p><span>Here is <em>some text</em></span>
Line-padding will be inserted such that
an extra 0.5em of inline background will be visible
on each side of each line.
If it renders such that there is a break between “some” and “text”,
the additional padding will be:
on the first line, black on the left and green on the right,
and on the second line, green on both sides.
Here is sometext
Automatic Contextual Spacing: the 'text-autospace' property
Name: text-autospace
Value: normal | <> | auto
Initial: normal
Applies to: text
Inherited: yes
Percentages: N/A
Computed value: specified keyword(s)
Animation type: discrete
parsing/text-autospace-computed.html
parsing/text-autospace-invalid.html
parsing/text-autospace-valid.html
text-autospace/text-autospace-001.html
text-autospace/text-autospace-break-001.html
Controls spacing between adjacent characters
on the same line within the same [=inline formatting context=]
using a set of character-class-based rules,
allowing for automatic control over inter-script spacing
and for spacing around punctuation.
text-autospace/text-autospace-vertical-combine-001.html
text-autospace/text-autospace-vertical-upright-001.html
Values are defined as follows:
Same behavior as ''ideograph-alpha ideograph-numeric''.
text-autospace/text-autospace-break-001.html
text-autospace/text-autospace-dynamic-001.html
text-autospace/text-autospace-dynamic-text-001.html
text-autospace/text-autospace-dynamic-text-002.html
text-autospace/text-autospace-dynamic-text-003.html
text-autospace/text-autospace-dynamic-text-004.html
text-autospace/text-autospace-first-line-001.html
text-autospace/text-autospace-ligature-001.html
text-autospace/text-autospace-mixed-001.html
no-autospace
No automatic space is inserted.
text-autospace/text-autospace-001.html
text-autospace/text-autospace-no-001.html
text-autospace/text-autospace-dynamic-001.html
text-autospace/text-autospace-ligature-001.html
text-autospace/text-autospace-mixed-001.html
insert
The specified spacing is automatically inserted
if there are no space characters of any kind ([=Unicode general category=] Z) already there.
If neither ''text-autospace/insert'' nor ''text-autospace/replace'' are specified,
the behavior is the same as ''text-autospace/insert''.
replace
The specified spacing is automatically inserted
even if there is already a [=space=] (U+0020) at that point;
additionally, the [=space=] (U+0020) is removed.
Other types of space characters ([=Unicode general category=] Z)
suppress automatic spacing, as for ''text-autospace/insert''.
Note: This is for correcting text which is using the easy-to-type U+0020
instead of proper spacing.
ideograph-alpha
Creates extra spacing between runs of
ideographs and non-ideographic letters,
see [[#inter-script-spacing]].
text-autospace/text-autospace-ideogram-alpha-001.html
Creates extra non-breaking spacing around punctuation as required by language-specific typographic conventions.
In this level, if the element's content language is French,
narrow no-break space (U+202F) and no-break space (U+00A0) is inserted
where required by French typographic guidelines.
Otherwise this value has no effect.
However future specifications may add automatic spacing behavior for other languages.
auto
The user agent chooses a set of typographically high quality spacing values.
Different user agents running on different platforms may pick different values.
Note: These spacing values may or may not match OS platform conventions.
This property is additive with the 'word-spacing' and 'letter-spacing' properties.
That is, the amount of spacing contributed by the 'letter-spacing' setting (if any)
is added to the spacing created by 'text-autospace'.
The same applies to 'word-spacing'.
At element boundaries, the amount of extra spacing introduced between characters
is determined by and rendered within the innermost element that contains the boundary.
Inter-script Spacing
The ''ideograph-alpha'' and ''ideograph-numeric'' values
introduce spacing at the boundary between particular classes of characters
when they are directly adjoining on a line,
i.e. without any intervening non-zero [=margin=], [=border=], or [=padding=]
or intervening characters (such as a quotation mark or a space).
The amount of space introduced by these keywords is 1/8 of the CJK advance measure,
i.e ''0.125ic''.
Note: Spacing conventions vary, but values typically range from 1/4ic to as low as 1/8ic,
with 1/4ic being more common in historical contexts due to metal type limitations
and 1/6ic or thinner being more common in proportional typesetting.
Because these spaces are inserted by default
(through the initial value, ''text-spacing/normal''),
CSS uses 1/8ic in order to be conservative in its interference.
A future level of this module may introduce control
over the amount of spacing.
CJK Punctuation Spacing: the 'text-spacing-trim' property
Name: text-spacing-trim
Value: <> | auto
Initial: normal
Applies to: text
Inherited: yes
Percentages: N/A
Computed value: specified keyword(s)
Animation type: discrete
parsing/text-spacing-trim-computed.html
parsing/text-spacing-trim-invalid.html
parsing/text-spacing-trim-valid.html
text-spacing-trim/text-spacing-trim-001.html
text-spacing-trim/text-spacing-trim-colon-001.html
text-spacing-trim/text-spacing-trim-combinations-001.html
text-spacing-trim/text-spacing-trim-dot-001.html
Controls spacing around CJK punctuation characters
on the same line within the same [=inline formatting context=]
using a set of character-class-based rules,
allowing them to be set halfwidth or fullwidth
based on their position and neighbors within the line.
Values are defined as follows:
All fullwidth punctuation characters are set with full-width glyphs (spaced).
text-spacing-trim/text-spacing-trim-space-all-001.html
text-spacing-trim/text-spacing-trim-dynamic-001.html
normal
Set fullwidth opening punctuation with full-width glyphs (spaced)
at the start of each line;
set fullwidth closing punctuation with half-width glyphs (flush)
at the end of each line
if it does not otherwise fit prior to justification,
else set the punctuation with full-width glyphs;
and collapse spacing between punctuation glyphs
as described below.
text-spacing-trim/text-spacing-trim-span-001.html
text-spacing-trim/text-spacing-trim-subset-001.html
Set fullwidth opening punctuation with full-width glyphs (spaced)
on the first line of the [=block container=]
and each line after a [=forced line break=].
Otherwise as ''text-spacing/normal''.
text-spacing-trim/text-spacing-trim-001.html
text-spacing-trim/text-spacing-trim-colon-001.html
text-spacing-trim/text-spacing-trim-combinations-001.html
text-spacing-trim/text-spacing-trim-dot-001.html
text-spacing-trim/text-spacing-trim-quote-001.html
text-spacing-trim/text-spacing-trim-start-001.html
text-spacing-trim/text-spacing-trim-span-001.html
This value exists for compat requirements.
This value exists to manage formatting of some existing Chinese and Japanese content,
for which ''trim-both'' would have been appropriate typographically,
except that they are already written
to expect the first line to be set as for ''space-all''.
Specifically,
due to the lack of reliable 'hanging-punctuation' support across UAs,
existing content (especially ePub content)
uses U+3000 ideographic space in place of 'text-indent',
but omits it when the paragraph begins with punctuation
that is desired to hang in the indent
in order to create the hanging punctuation effect.
Using ''trim-both'' on the first line
would thus trim away the effective indent in such content
and thus obscure that line's distinction
as the first line of a new paragraph.
Note that this typesetting practice
of using ideographic spaces for indentation
(sometimes and not always)
is contrary to the separation of content and style offered by HTML and CSS.
Using 'hanging-punctuation' and 'text-indent'
to control paragraph formatting
rather than tweaking the text content of the document
preserves the text’s true semantics in the document source
and allows the style sheet designer
to freely switch among the various spacing/indentation styles
without needing to alter the content.
See [[#japanese-start-edges]] for examples.
Additionally, the behavior at the end of lines is aligned
with the ''text-spacing-trim/normal'' and ''trim-start'' values
rather than ''text-spacing-trim/trim-both'',
in that it only trims the glyphs
if they do not otherwise fit prior to justification.
While improving the typography in fewer cases,
it is closer to the legacy behavior of ''space-all''
which reduces compatibility concerns.
trim-start
Set fullwidth opening punctuation with half-width glyphs (flush)
at the start of each line.
Otherwise as ''text-spacing-trimm/normal''.
text-spacing-trim/text-spacing-trim-start-001.html
text-spacing-trim/text-spacing-trim-start-002.html
text-spacing-trim/text-spacing-trim-end-001.html
text-spacing-trim/text-spacing-trim-span-001.html
The user agent chooses a set of typographically high quality spacing values.
Different user agents running on different platforms may pick different values.
Note: These spacing values may or may not match OS platform conventions.
ISSUE: Do we need ''text-spacing-trim/auto''? It would be weird for the author to choose platform-dependent behavior at the start of the first line, and it should otherwise use ''text-spacing-trim/trim-both''.
Here is an informal summary of what the various values do:
Value
Trim at line start
Trim at line end
Trim adjacent pairs
Trim everywhere
''space-all''
no
''text-spacing-trim/normal''
no
only if would not fit
yes
no
''space-first''
yes except on the first line
''trim-start''
yes
''trim-both''
yes
''trim-all''
yes
''text-spacing-trim/auto''
user-agent specific / platform dependent
Fullwidth Punctuation Collapsing
Typically, fullwidth characters have glyphs with the same advance width
as a standard Han character (e.g. 水 U+6C34).
However, many fullwidth punctuation glyphs only take up part of the fullwidth design space.
Thus such punctuation are not always set fullwidth.
Several values of 'text-spacing-trim' allow the author to control
when such characters are set half-width (typically half the width of an ideograph)
and when they are set full-width.
In order to set the text as specified, the UA will need to either
trim (kern) the blank half of the glyphs,
if they are given full-width and must be set half-width, or
add space to the glyphs,
if they are given half-width and must be set full-width.
The UA may use the OpenType halt and vhal features
if implemented by a font
in order to perform the requisite trimming of a particular glyph.
The UA must not use the hwid feature
or otherwise substitute halfwidth forms
as switching to halfwidth glyphs can change the glyph shape
which is not acceptable here.
Some fonts use proportional glyphs for fullwidth punctuation characters.
If there is no support in the font for distinguishing
fullwidth vs halfwidth glyph shapes
(e.g. through font features),
then for such proportional glyphs,
the given advance width is considered
simultaneously full-width and half-width:
the UA must not add or remove space to these glyphs.
text-spacing-trim/text-spacing-trim-feature-001.html
Note: The advance width of a standard Han character
can be determined either from font metrics
such as the OpenType ideo and idtp baselines for the opposite writing mode,
or by taking the advance width of a Han character such as 水 U+6C34.
(The opposite writing mode must be used because some fonts are compressed
so that the characters are not square.)
More information on OpenType metrics can be found
in the OpenType spec.
Note that if 水 U+6C34, 卜 U+535C, and 一 U+4E00 do not all have the same advance width,
the font has proportional ideographs
and the fullwidth advance width cannot be reliably determined by measuring glyphs.
Some fonts have fullwidth punctuation characters
whose blank are too small to trim (kern.)
UA may choose not to trim (kern)
when the UA determined the trimming (kerning) may cause
glyph cut-offs, collisions, or excessive kerning
through glyph bounding box, glyph metrics, or font features.
If 'text-spacing-trim' is ''trim-all'',
the UA must collapse the space typically associated with such full width glyphs
regardless of the context in which they appear.
Otherwise, unless 'text-spacing-trim' is set to ''space-all''
(or the font has proportional fullwidth punctuation glyphs),
the UA must collapse the space typically associated with such full width glyphs
when placed adjacently on a line
as follows:
Set fullwidth opening punctuation half-width if the previous character is any of:
* a fullwidth opening punctuation
text-spacing-trim/text-spacing-trim-001.html
text-spacing-trim/text-spacing-trim-colon-001.html
* a fullwidth middle dot punctuation
text-spacing-trim/text-spacing-trim-dot-001.html
* an ideographic space (U+3000)
text-spacing-trim/text-spacing-trim-001.html
* a fullwidth closing punctuation of an equivalent or larger 'font-size'
text-spacing-trim/text-spacing-trim-001.html
* a character belonging to Unicode [=general category=] Ps
text-spacing-trim/text-spacing-trim-quote-001.html
text-spacing-trim/text-spacing-trim-narrow-001.html
Otherwise set it full-width.
Set fullwidth closing punctuation half-width if the next character is any of:
* a fullwidth closing punctuation
text-spacing-trim/text-spacing-trim-001.html
* a fullwidth middle dot punctuation
text-spacing-trim/text-spacing-trim-dot-001.html
* an ideographic space (U+3000)
text-spacing-trim/text-spacing-trim-001.html
* a fullwidth opening punctuation of a larger 'font-size'
* a character belonging to Unicode [=general category=] Pe
text-spacing-trim/text-spacing-trim-narrow-001.html
Otherwise set it full-width.
The following example table lists the punctuation pairs
affected by adjacent-pairs trimming.
It uses halfwidth equivalents to approximate the trimming effect.
Demonstration of adjacent-pairs punctuation trimming
Combination
Sample Pair
Looks Like
Opening—Opening
〔+（
〔(
Middle Dot—Opening
・+（
・(
Closing—Opening
〕+（
〕(
Ideographic Space—Opening
+（
(
Closing—Closing
）+〕
)〕
Closing—Middle Dot
）+・
)・
Closing—Ideographic Space
）+
)
Text Spacing Character Classes
In the context of this property the following definitions apply:
Issue(9503): Classes and Unicode code points are under review,
and at least some changes are needed to accommodate more recent additions to Unicode.
ideographs
Includes all [=typographic character units=] [[CSS-TEXT-3]] whose base character is listed below:
All characters in the range of U+3041 to U+30FF,
except those that belong to Unicode Punctuation [P*] [=general category=].
CJK Strokes (U+31C0 to U+31EF).
Katakana Phonetic Extensions (U+31F0 to U+31FF).
All characters that have the Han [=script property=].
non-ideographic letters
Includes all [=typographic character units=] that
belong to Unicode Letters [L*] and Mark [M*] [=general category=],
except when any of the following conditions are met:
is categorized as East Asian Fullwidth (F) by [[!UAX11]].
is upright in vertical text flow using the 'text-orientation' property
or the 'text-combine-upright' property.
text-autospace/text-autospace-vertical-upright-001.html
text-autospace/text-autospace-vertical-combine-001.html
non-ideographic numerals
Includes all [=typographic character=] units that
belong to the Unicode Decimal Digit Number [Nd] [=general category=],
except when any of the following conditions are met:
is categorized as East Asian Fullwidth (F) by [[!UAX11]].
is upright in vertical text flow using the 'text-orientation' property
or the 'text-combine-upright' property.
fullwidth opening punctuation
Includes any opening punctuation character (Unicode category Ps)
that belongs to the CJK Symbols and Punctuation block (U+3000–U+303F)
or is categorized as East Asian Fullwidth (F) by [[!UAX11]].
Also includes LEFT SINGLE QUOTATION MARK (U+2018) and LEFT DOUBLE QUOTATION MARK (U+201C).
When trimmed, the left (for horizontal text) or top (for vertical text) half is kerned.
fullwidth closing punctuation
Includes any closing punctuation character (Unicode category Pe)
that belongs to the CJK Symbols and Punctuation block (U+3000–U+303F)
or is categorized as East Asian Fullwidth (F) by [[!UAX11]].
Also includes RIGHT SINGLE QUOTATION MARK (U+2019) and RIGHT DOUBLE QUOTATION MARK (U+201D).
May also include [=fullwidth colon punctuation=] and/or [=fullwidth dot punctuation=]
(see below).
When trimmed, the right (for horizontal text) or bottom (for vertical text) half is kerned.
fullwidth middle dot punctuation
Includes MIDDLE DOT (U+00B7), HYPHENATION POINT (U+2027), and KATAKANA MIDDLE DOT (U+30FB).
May also include [=fullwidth colon punctuation=] and/or [=fullwidth dot punctuation=]
(see below).
fullwidth colon punctuation
Includes FULLWIDTH COLON (U+FF1A) and FULLWIDTH SEMICOLON (U+FF1B).
fullwidth dot punctuation
Includes
IDEOGRAPHIC COMMA (U+3001),
IDEOGRAPHIC FULL STOP (U+3002),
FULLWIDTH COMMA (U+FF0C),
FULLWIDTH FULL STOP (U+FF0E).
Whether [=fullwidth colon punctuation=] and [=fullwidth dot punctuation=]
should be considered [=fullwidth closing punctuation=] or [=fullwidth middle dot punctuation=]
depends on where in the glyph's box the punctuation is drawn.
If the punctuation is centered,
then it should be considered middle dot punctuation.
If the punctuation is drawn to one side (left in horizontal text, top in vertical text)
and the other half is therefore blank
then the punctuation should be considered closing punctuation and trimmed accordingly.
The UA must classify [=fullwidth colon punctuation=] and [=fullwidth dot punctuation=]
under either the [=fullwidth closing punctuation=] category or the [=fullwidth middle dot punctuation=] category
as appropriate.
The UA may rely on language conventions and the writing mode (horizontal vs. vertical),
and/or font information to determine this categorization.
The UA may also add additional characters to any category as appropriate.
The following informative table summarizes language conventions
for classifying fullwidth colon and dot punctuation:
colon punctuation
dot punctuation
Simplified Chinese (horizontal)
closing
closing
Simplified Chinese (vertical)
closing
closing
Traditional Chinese
middle dot
middle dot
Korean
middle dot
closing
Japanese
middle dot
closing
Note that for Chinese fonts at least,
the author observes that the standard convention is often not followed.
Japanese Paragraph-start Conventions in CSS
Japanese has three common start-edge typesetting schemes,
which are distinguished by their handling of opening brackets.
Positioning of opening brackets at line head [[JLREQ]]
Assuming a UA style sheet of p { margin: 1em 0; },
CSS can achieve the Japanese typesetting styles with the following rules:
Brackets flush with indent, flush with other lines (first scheme):
Character Class Spacing Shorthand: the 'text-spacing' property
Name: text-spacing
Value: none | auto | <> || <>
Initial: see individual properties
Applies to: text
Inherited: yes
Percentages: N/A
Computed value: specified keyword(s)
Animation type: discrete
parsing/text-spacing-computed.html
parsing/text-spacing-invalid.html
parsing/text-spacing-valid.html
This property is a shorthand
for setting 'text-spacing-trim' and 'text-autospace' in a single declaration.
Values are defined as follows:
none
Turns off all text-spacing features:
sets 'text-spacing-trim' to ''space-all''
and 'text-autospace' to ''no-autospace''.
auto
Sets both 'text-spacing-trim' and 'text-autospace' to ''text-autospace/auto''.
<>
Sets 'text-spacing-trim' to the specified value.
If no <> value is given,
'text-autospace' is set to its [=initial value=].
<>
Sets 'text-autospace' to the specified value.
If no <> value is given,
'text-spacing-trim' is set to its [=initial value=].
Note: As ''text-spacing-trim/normal'' is the initial value of both 'text-spacing-trim' and 'text-autospace',
''text-spacing: normal'' resets both to their initial values.
Shaping Across Element Boundaries
Text shaping must be broken at inline box boundaries
when any of the following are true
for any box whose boundary separates the two [=typographic character units=]:
Any of 'margin'/'border'/'padding'
separating the two [=typographic character units=] in the inline axis
is non-zero.
shaping/shaping-009.html
shaping/reference/shaping-009-ref.html
shaping/shaping-010.html
shaping/reference/shaping-010-ref.html
shaping/shaping-011.html
shaping/reference/shaping-011-ref.html
boundary-shaping/boundary-shaping-003.html
boundary-shaping/boundary-shaping-004.html
boundary-shaping/boundary-shaping-005.html
boundary-shaping/boundary-shaping-007.html
boundary-shaping/boundary-shaping-009.html
'vertical-align' is not ''vertical-align/baseline''.
boundary-shaping/boundary-shaping-002.html
boundary-shaping/boundary-shaping-006.html
The boundary is a [=bidi-isolates|bidi isolation boundary=].
shaping/shaping-012.html
shaping/reference/shaping-012-ref.html
shaping/shaping-013.html
boundary-shaping/boundary-shaping-008.html
Text shaping must not be broken across inline box boundaries
when there is no effective change in formatting,
or if the only formatting changes do not affect the glyphs
(as in applying text decoration).
text-transform/text-transform-shaping-001.html
text-transform/text-transform-shaping-002.html
text-transform/text-transform-shaping-003.html
shaping/shaping-000.html
shaping/reference/shaping-000-ref.html
shaping/shaping-004.html
shaping/shaping-005.html
shaping/shaping-006.html
shaping/shaping-007.html
shaping/shaping-014.html
shaping/reference/shaping-014-ref.html
shaping/shaping-016.html
shaping/reference/shaping-016-ref.html
shaping/shaping-022.html
shaping/reference/shaping-022-ref.html
shaping/shaping-025.html
shaping/reference/shaping-025-ref.html
shaping/shaping_lig-000.html
boundary-shaping/boundary-shaping-001.html
boundary-shaping/boundary-shaping-010.html
Text shaping should not be broken across inline box boundaries otherwise,
if it is reasonable and possible for that case given the limitations of the font technology.
shaping/shaping-001.html
shaping/reference/shaping-001-ref.html
shaping/shaping-002.html
shaping/reference/shaping-002-ref.html
shaping/shaping-003.html
shaping/reference/shaping-003-ref.html
shaping/shaping-008.html
shaping/reference/shaping-008-ref.html
shaping/shaping-017.html
shaping/shaping-018.html
shaping/shaping-020.html
shaping/reference/shaping-020-ref.html
shaping/shaping-021.html
shaping/reference/shaping-021-ref.html
shaping/shaping-023.html
shaping/reference/shaping-023-ref.html
shaping/shaping-024.html
shaping/reference/shaping-024-ref.html
boundary-shaping/boundary-shaping-009.html
An example of reasonable and possible shaping across boundaries
is Arabic shaping:
in many systems this is performed by the font engine,
allowing the font to provide variant glyphs
with potentially very sophisticated contextual shaping.
It’s not generally possible to rely on this system across a font change
unless the font engine has an API to provide context,
but it is straightforward and therefore quite reasonable
for an engine to work around this limitation by, for example,
using the zero-width-joiner (U+200D) or zero-width-non-joiner (U+200C)
as appropriate to solicit the correct choice of
initial/medial/final/isolated glyph.
An example of possible but not reasonable shaping across boundaries
is handling a font that is sensitive to 20 characters of context
on either side to choose its glyphs:
passing all the text before and after the string in question,
even through multiple inline boundaries with formatting changes,
is complicated.
The UA could handle such cases,
but is not required to,
as they are not typical or fundamentally required
by any modern writing system.
An example of impossible shaping across boundaries
is a change in font weight partway through the word “and”
in a font where a ligature would replace
all three letters of the word “and”
with an ampersand glyph (“&”).
Edge Effects
Edge effects control
the indentation of lines with respect to other lines in the block ('text-indent')
and how content is measured at the start and end edges of a line ('hanging-punctuation').
First Line Indentation: the 'text-indent' property
Name: text-indent
Value: [ <> ] && hanging? && each-line?
Initial: 0
Applies to: block containers
Inherited: yes
Percentages: refers to block container’s own inline-axisinner size
Computed value: computed <> value, plus any specified keywords
Animation type: by computed value type
Canonical order: per grammar
inheritance.html
parsing/text-indent-valid.html
parsing/text-indent-invalid.html
parsing/text-indent-computed.html
animations/text-indent-interpolation.html
animations/text-indent-composition.html
text-indent/text-indent-long-line-crash.html
text-indent/anonymous-flex-item-001.html
text-indent/anonymous-grid-item-001.html
c547-indent-000.xht
c547-indent-001.xht
text-indent-012.xht
text-indent-013.xht
text-indent-014.xht
text-indent-112.xht
text-indent-applies-to-001.xht
text-indent-applies-to-002.xht
text-indent-applies-to-003.xht
text-indent-applies-to-005.xht
text-indent-applies-to-006.xht
text-indent-applies-to-007.xht
text-indent-applies-to-008.xht
text-indent-applies-to-009.xht
text-indent-applies-to-010.xht
text-indent-applies-to-011.xht
text-indent-applies-to-012.xht
text-indent-applies-to-013.xht
text-indent-applies-to-014.xht
text-indent-applies-to-015.xht
text-indent-inherited-001.xht
This property specifies the indentation
applied to lines of inline content in a block.
The indent is treated as a margin
applied to the start edge of the line box.
text-indent-010.xht
text-indent-012.xht
text-indent-013.xht
text-indent-115.xht
text-indent-on-blank-line-rtl-left-align.html
text-indent-overflow-001.xht
text-indent-overflow-002.xht
text-indent-overflow-003.xht
text-indent-overflow-004.xht
text-indent-rtl-001.xht
text-indent-rtl-002.xht
text-indent/text-indent-min-max-content-001.html
text-indent/text-indent-overflow.html
text-indent/text-indent-text-align-end.html
text-indent/below-float.html
Unless otherwise specified
by the ''each-line'' and/or ''text-indent/hanging'' keywords,
only lines that are the
[=first formatted line=]
of an element are affected.
[[!CSS-PSEUDO-4]]
For example, the first line of an anonymous block box is only affected
if it is the first child of its parent element.
text-indent-014.xht
text-indent-wrap-001.xht
text-indent/text-indent-with-absolute-pos-child.html
Values have the following meanings:
Gives the amount of the indent
as a percentage of the block container’s own logical width.
text-indent-011.xht
text-indent-100.xht
text-indent-101.xht
text-indent-102.xht
text-indent-103.xht
text-indent-104.xht
text-indent-percent-001.xht
Percentages must be treated as ''0''
for the purpose of calculating [=intrinsic size contributions=],
but are always resolved normally when performing layout.
text-indent/percentage-value-intrinsic-size.html
text-indent/text-indent-percentage-001.xht
text-indent/text-indent-percentage-002.html
text-indent/text-indent-percentage-003.html
text-indent/text-indent-percentage-004.html
Note: This can lead to the element overflowing.
It is not recommended to use percentage indents and intrinsic sizing together.
each-line
Indentation affects the first line of each block container
and each line after a forced line break
(but not lines after a soft wrap break).
text-indent/text-indent-each-line-hanging.html
hanging
Inverts which lines are affected.
text-indent/text-indent-each-line-hanging.html
If 'text-align' is ''text-align/start'' and 'text-indent' is ''5em'' in
left-to-right text with no floats present, then first line of text
will start 5em into the block:
Since CSS1 it has been possible to
indent the first line of a block element
5em by setting the 'text-indent' property
to '5em'.
If we add the ''text-indent/hanging'' keyword,
then the first line will start flush,
but other lines will be indented 5em:
In CSS3 we can instead indent all other
lines of the block element by 5em
by setting the 'text-indent' property
to 'hanging 5em'.
Since the 'text-indent' property only affects the “first formatted line”,
a line after a forced break will not be indented.
For example, in the middle of
this paragraph is an equation,
which is centered:
x + y = z
The first line after the equation
is flush (else it would look like
we started a new paragraph).
However, sometimes (as in poetry or code),
it is appropriate to indent each line
that happens to be long enough to wrap.
In the following example, 'text-indent'
is given a value of ''3em hanging each-line'',
giving the third line of the poem a hanging indent
where it soft-wraps at the block’s right boundary:
In a short line of text
There need be no wrapping,
But when we go on and on and on
and on,
Sometimes a soft break
Can help us stay on the page.
Note: Since the 'text-indent' property inherits,
when specified on a block element, it will affect descendant
inline-block elements.
For this reason, it is often wise to specify ''text-indent: 0'' on
elements that are specified ''display: inline-block''.
Hanging Glyphs
When a glyph at the start or end edge of a line hangs,
it is not considered
when measuring the line’s contents for fit, alignment, or justification.
Depending on the line’s alignment/justification, this can
result in the mark being placed outside the line box.
The [=hanging=] glyph is also not taken into account
when computing [=intrinsic sizes=] ([=min-content size=] and [=max-content size=]),
and any sizes derived thereof.
(The interaction of this measurement and kerning is currently UA-defined;
the CSSWG welcomes advice on this point.)
white-space/full-width-leading-spaces-004.html
white-space/white-space-intrinsic-size-005.html
white-space/white-space-intrinsic-size-006.html
overflow-wrap/overflow-wrap-min-content-size-009.html
A hanging glyph
is still enclosed inside its parent inline box
and still participates in text justification:
its character advance is just not measured when determining
how much content fits on the line,
how much the line’s contents need to be expanded or compressed for justification,
or how to position the content within the line box for text alignment.
Effectively, the [=hanging=] glyph character advance
is re-interpreted as an additional negative margin
on the affected edge of its parent [=inline box=];
the line is otherwise laid out as usual.
An overflowing [=hanging glyph=] should typically be considered
[=ink overflow=]
so as to avoid creating unnecessary scrollbars,
but the UA may treat it as [=scrollable overflow=]
when the content is editable
or in other circumstances where treating it as [=scrollable overflow=]
would be useful to the user.
[[!CSS-OVERFLOW-3]]
hanging-punctuation/hanging-scrollable-001.html
white-space/white-space-intrinsic-size-019.html
white-space/white-space-intrinsic-size-020.html
hanging-punctuation/hanging-punctuation-block-bound-001.html
hanging-punctuation/hanging-punctuation-inline-bound-001.html
white-space/trailing-space-and-text-alignment-001.html
white-space/trailing-space-and-text-alignment-003.html
white-space/trailing-space-and-text-alignment-005.html
white-space/trailing-space-and-text-alignment-rtl-001.html
white-space/trailing-space-and-text-alignment-rtl-003.html
white-space/trailing-space-and-text-alignment-rtl-005.html
white-space/white-space-pre-wrap-trailing-spaces-021.html
white-space/white-space-pre-wrap-trailing-spaces-022.html
white-space/white-space-pre-wrap-trailing-spaces-023.html
text-justify/text-justify-and-trailing-spaces-001.html
text-justify/text-justify-and-trailing-spaces-002.html
text-justify/text-justify-and-trailing-spaces-003.html
text-justify/text-justify-and-trailing-spaces-004.html
text-justify/text-justify-and-trailing-spaces-005.html
text-justify/text-justify-and-trailing-spaces-006.html
In some cases, a glyph at the end of a line
can conditionally hang:
it [=hangs=] only if it does not otherwise fit in the line prior to justification.
It is not considered when measuring the line’s contents for fit;
however, any part of it that does not fit
is considered to [=hang=].
Glyphs that [=conditionally hang=] are not taken into account
when computing [=min-content sizes=]
and any sizes derived thereof,
but they are taken into account for [=max-content sizes=]
and any sizes derived thereof.
white-space/white-space-intrinsic-size-013.html
white-space/white-space-intrinsic-size-014.html
white-space/white-space-intrinsic-size-017.html
Non-zero inline-axis borders or padding between
a [=hang=]able glyph and the edge of the line prevent the glyph from hanging.
For example, a period at the end of an inline box with end padding
does not [=hang=] at the end edge of a line.
Multiple adjacent glyphs can hang together,
however specific limits on how many are allowed to hang may be specified
(e.g. at most one punctuation character may [=hang=] at each edge of the line).
Hanging Punctuation: the 'hanging-punctuation' property
Name: hanging-punctuation
Value: none | [ first || [ force-end | allow-end ] || last ]
Initial: none
Applies to: text
Inherited: yes
Canonical order: per grammar
Computed value: specified keyword(s)
Animation type: discrete
inheritance.html
parsing/hanging-punctuation-valid.html
parsing/hanging-punctuation-invalid.html
hanging-punctuation/hanging-punctuation-inline-001.html
This property determines whether a punctuation mark,
if one is present,
[=hangs=] and may be placed outside the line box (or in the indent)
at the start or at the end of a line of text.
Note: If there is not sufficient padding on the
block container, 'hanging-punctuation' can trigger overflow.
Values have the following meanings:
none
No punctuation character is made to [=hang=].
first
An opening bracket, quote, or ideographic space at the start
of the [=first formatted line=]
of an element [=hangs=].
This applies to all characters in the Unicode categories Ps, Pf, Pi
plus the ASCII quote marks U+0027 ' APOSTROPHE and U+0022 " QUOTATION MARK
and the IDEOGRAPHIC SPACE U+3000.
hanging-punctuation/hanging-punctuation-first-001.xht
hanging-punctuation/hanging-punctuation-first-002.html
last
A closing bracket or quote at the end
of the last formatted line of an element [=hangs=].
This applies to all characters in the Unicode categories Pe, Pf, Pi
plus the ASCII quote marks U+0027 ' APOSTROPHE and U+0022 " QUOTATION MARK.
hanging-punctuation/hanging-punctuation-last-001.xht
force-end
A [=stop or comma=] at the end of a line [=hangs=].
hanging-punctuation/hanging-punctuation-force-end-001.xht
allow-end
A [=stop or comma=] at the end of a line [=conditionally hangs=].
hanging-punctuation/hanging-punctuation-allow-end-001.xht
At most one punctuation character may [=hang=] at each edge of the line.
Stops and commas allowed to [=hang=] include:
U+002C
,
COMMA
U+002E
.
FULL STOP
U+060C
،
ARABIC COMMA
U+06D4
۔
ARABIC FULL STOP
U+3001
、
IDEOGRAPHIC COMMA
U+3002
。
IDEOGRAPHIC FULL STOP
U+FF0C
，
FULLWIDTH COMMA
U+FF0E
．
FULLWIDTH FULL STOP
U+FE50
﹐
SMALL COMMA
U+FE51
﹑
SMALL IDEOGRAPHIC COMMA
U+FE52
﹒
SMALL FULL STOP
U+FF61
｡
HALFWIDTH IDEOGRAPHIC FULL STOP
U+FF64
､
HALFWIDTH IDEOGRAPHIC COMMA
The UA may include other characters as appropriate.
Note: The CSS Working Group would appreciate if UAs including
other characters would inform the working group
of such additions.
The ''hanging-punctuation/allow-end'' and ''force-end'' are two variations
of hanging punctuation used in East Asia.
p {
text-align: justify;
hanging-punctuation: allow-end;
}
p {
text-align: justify;
hanging-punctuation: force-end;
}
The punctuation at the end of the first line for ''hanging-punctuation/allow-end''
does not hang, because it fits without hanging.
However, if ''force-end'' is used, it is forced to hang.
The justification measures the line without the hanging punctuation.
Therefore when the line is expanded, the punctuation is pushed outside the line.
Bidirectionality and Line Boxes
The start
and end sides of a line box
are determined by the [=inline base direction=] of the line box.
Although they usually match,
the [=inline base direction=] of a [=line box=]
is distinct from the [=inline base direction=]
of the [=containing block=] or the [=bidi paragraph=].
The [=line box=]’s [=inline base direction=] affects
'text-align-all', 'text-align-last', 'text-indent', and 'hanging-punctuation'--
i.e. the position and alignment of its contents with respect to its edges.
It does not affect the formatting or ordering of inline content
(which is controlled by the Unicode Bidirectional Algorithm
as applied by CSS Writing Modes
[[!UAX9]]
[[CSS-WRITING-MODES-4]]).
In most cases, a [=line box=]’s [=inline base direction=]
is given by its [=containing block=]’s computed 'direction'.
However,
if its [=containing block=] has ''unicode-bidi: plaintext''
[[!CSS-WRITING-MODES-4]]:
If the [=bidi paragraph=] to which the [=line box=] belongs
(that is, the [=bidi paragraph=] for which the line box holds content)
has strong directionality,
the line box’s [=inline base direction=] is that direction.
bidi/bidi-lines-001.html
bidi/bidi-lines-002.html
If the [=line box=] is empty
(i.e. contains no [=atomic inlines=] or
characters other than the newline character, if any)
or otherwise has no strong directionality
(contains only weak or neutral characters),
its [=inline base direction=] is taken
from the preceding line box (if any),
or, if this is the first line box in the containing block,
from the 'direction' property of the containing block.
(This can result in an RTL line box whose contents have an LTR base direction.)
bidi/bidi-lines-002.html
In the following example,
assuming the <block>
is a start-aligned preformatted block
(''display: block; white-space: pre; text-align: start''),
every other line is right-aligned:
<block style="unicode-bidi: plaintext">
français
فارسی
français
فارسی
français
فارسی
</block>
Because neutral characters (such as punctuation)
and isolated runs are skipped
when finding the inline base direction of a plaintext bidi paragraph,
the line box in the following example will be left-to-right
(and thus left-aligned given ''text-align: start''),
as dictated by the first strong character, ‘h’:
<para style="display: block; direction: rtl; unicode-bidi:plaintext">
“<quote style="unicode-bidi:plaintext">שלום!</quote>”, they said.
</para>
<textarea style="direction: rtl; unicode-bidi:plaintext">
Hello!
</textarea>
Because of ''unicode-bidi: plaintext'',
the “Hello!” is typeset LTR
(i.e. with the exclamation mark on the right side)
and left-aligned,
ignoring the containing block’s RTL 'direction'.
This makes the empty line following it LTR as well,
which means that a caret on that line should appear at its left edge.
The empty first line, however, is right-aligned:
having no preceding line,
it assumes the RTL direction of its containing block.
Appendix A:
Text Processing Order of Operations
This appendix is normative.
The following list defines the order of text operations.
(Implementations are not bound to this order as long as the resulting layout is the same.)
[[#white-space-trim]]
[[#white-space-phase-1|white space processing]] part I (pre-wrapping)
[[#word-space-transform]] and
[[#transforming|text transformation]]
word-space-transform/word-space-transform-007.html
word-space-transform/word-space-transform-008.html
word-space-transform/word-space-transform-009.html
word-space-transform/word-space-transform-030.html
[=wrapping|text wrapping=] while applying per line:
* [[#text-indent-property|indentation]]
* [[css-writing-modes-4#text-direction|bidirectional reordering]] [[!CSS2]] / [[!CSS-WRITING-MODES-4]]
* [[#white-space-phase-2|white space processing]] part II
* font/glyph selection and positioning [[!CSS-FONTS-3]]
* 'letter-spacing', 'word-spacing', 'text-spacing', and 'line-padding'
* [[#hanging-punctuation-property|hanging punctuation]]
[[#justification|justification]]
(which may affect glyph selection and/or text wrapping, looping back into that step)
[[#text-align-property|text alignment]]
[[#text-group-align-property|text group alignment]]
letter-spacing/letter-spacing-bidi-003.xht
Appendix B:
Conversion to Plaintext
This appendix is normative for the purpose of plaintext copy-paste operations.
When a CSS-rendered document is converted to a plaintext format,
it is expected that:
The 'text-transform' property has no effect.
'white-space-trim' and [[#white-space-phase-1]] is applied
and any sequence of [=collapsible=] [=white space=]
at the beginning of a [=block=]
or immediately following a [=forced line break=]
is removed.
Appendix C:
Default UA Stylesheet
This appendix is informative,
and is to help UA developers to implement a default stylesheet for HTML,
but UA developers are free to ignore or modify as appropriate.
/* make option elements align together */
option { text-align: match-parent; }
/* do not allow white space to collapse in textarea */
textarea { white-space-collapse: preserve !important; }
/* preserve character grid in preformatted text */
pre, code, kbd, samp, tt { text-spacing: none; }
/* Avoid hanging punctuation inheriting into preformatted blocks */
pre { hanging-punctuation: none; }
Appendix D:
Scripts and Spacing
This appendix is normative.
Typographic behavior varies somewhat by language,
but varies drastically by writing system.
This appendix categorizes some common [=Unicode script|scripts=] in Unicode 6.0
according to their justification and spacing behavior.
Category descriptions are descriptive, not prescriptive;
the determining factor is the prioritization of [=justification opportunities=].
block scripts
CJK and by extension all Wide characters
(see East Asian Width [[!UAX11]]).
The following [=Unicode scripts=] are included:
Bopomofo, Han, Hangul, Hiragana, Katakana, and Yi.
Characters of the [=East Asian Width property=]
Wide and Fullwidth are also included,
but Ambiguous characters are included
only if the [=writing system=] is
Chinese,
Korean,
or Japanese.
clustered scripts
Clustered scripts have discrete units
and break only at word boundaries,
but do not use visible word separators.
They prioritize stretching spaces,
but comfortably admit inter-character spacing for justification.
The clustered scripts include,
but are not limited to,
the following [=Unicode scripts=]:
Khmer,
Lao,
Myanmar,
New Tai Lue,
Tai Le,
Tai Tham,
Tai Viet,
Thai
cursive scripts
Cursive scripts do not admit gaps
between their letters for either justification or 'letter-spacing'.
The following [=Unicode scripts=] are included:
Arabic,
Hanifi Rohingya,
Mandaic,
Mongolian,
N’Ko,
Phags Pa,
Syriac
Note: Indic scripts with baseline connectors
(such as Devanagari and Gujarati)
are not considered [=cursive scripts=],
and do admit such gaps
between [=typographic character units=].
See Indic Layout Requirements.
[[ILREQ]]
User agents should update this list
as they update their Unicode support
to handle as-yet-unencoded cursive scripts in future versions of Unicode,
and are encouraged to ask the CSSWG to update this spec accordingly.
Appendix E:
Characters and Properties
This appendix is normative.
Unicode defines four code point-level properties
that are referenced in CSS typesetting:
Unicode defines properties for individual code points,
but sometimes it is necessary to determine the properties
of a [=typographic character unit=].
For the purposes of CSS Text,
the properties of a [=typographic character unit=] are given
by the base character of its first [=grapheme cluster=]--
except in two cases:
[=Grapheme clusters=] formed with an Enclosing Mark
(Me)
of the Common script
are considered to be Other Symbols
(So)
in the Common script.
They are assumed to have the same Unicode properties
as the replacement character (U+FFFD).
[=Grapheme clusters=] formed with a Space Separator
(Zs)
as the base
are considered to be Modifier Symbols
(Sk).
They are assumed to have the same East Asian Width property as the base,
but take their other properties
from the first combining character in the sequence.
Appendix F:
Identifying the Content Writing System
This appendix is normative.
While most languages have a preferred writing system,
some have multiple, and
most can also be transcribed into one or more foreign writing systems.
As a common example, most languages have at least one Latin transcription,
and can thus be written in the Latin writing system.
Transcribed texts typically adopt the typographic conventions of the writing system:
for example Japanese “romaji” and Chinese Pinyin use Latin letters and word spaces,
and follow Latin line-breaking and justification practices accordingly.
As another example, historical ideographic Korean
(ko-Hani)
does not use word spaces,
and should therefore be typeset similar to Chinese
rather than modern Korean.
In HTML or any other [=document language=]
using BCP47 tags for identifying languages to declare the [=content language=],
authors can disambiguate or indicate the use of an atypical writing system
with script subtags.
[[BCP47]]
For example, to indicate use of the Latin writing system
for languages which don’t natively use it,
the -Latn script subtag can be added,
e.g. ja-Latn for Japanese romaji.
Other subtags exist for other writing systems,
see ISO’s Code for the Representation of Names of Scripts and the ISO15924 script tag registry.
[[ISO15924]]
Some common/historical examples of using BCP47 tags with script subtags:
zh-Latn
Chinese, written in Latin transcription.
ko-Hani
Korean, written in Hanja (Chinese ideographic characters).
tr-Arab
Turkish, written in Arabic script.
mn-Cyrl
Mongolian, written in Cyrillic.
mn-Mong
Mongolian, written in traditional Mongolian script.
However, BCP47 script subtags are not typically used
(and are in fact discouraged)
for languages strongly associated with a single writing system:
instead that writing system is expected to be implied
when no other is specified.
[[BCP47]]
IANA maintains a database of various languages’ most common writing system
via the Suppress-Script field in its
language subtag registry
for this purpose.
Note: More advice on language tagging can be found in
the Internationalization Working Group’s
“Language tags in HTML and XML”
and “Choosing a Language Tag”.
When no writing system is explicitly indicated,
UAs should assume the most common writing system
of the declared [=content language=]
for language-sensitive typographic behaviors
such as line-breaking or justification.
However, UAs must not assume that writing system
if the author has explicitly declared a different one.
If the UA has no language-specific knowledge
of a particular language and writing system combination,
it must use the typographic conventions of the declared writing system
(assuming the conventions of a different language if necessary),
not the conventions of the declared language in an assumed writing system,
which would be inappropriate to the declared writing system.
writing-system/writing-system-font-001.html
writing-system/writing-system-text-transform-001.html
writing-system/writing-system-segment-break-001.html
writing-system/writing-system-line-break-001.html
writing-system/writing-system-line-break-002.html
The full correspondence between languages and their most common writing systems
is out of scope for this document.
However, user agents must assume at least the following:
If the [=content language=] is Chinese and the [=writing system=] is unspecified,
or for any [=content language=]
if the [=writing system=] to specified to be one of the
''Hant'',
''Hans'',
''Hani'',
''Hanb'',
or ''Bopo''
ISO script codes,
then the [=writing system=] is Chinese.
If the [=content language=] is Japanese and the [=writing system=] is unspecified,
or for any [=content language=]
if the [=writing system=] to specified to be one of the
''Jpan'',
''Hrkt'',
''Hira'',
or ''Kana'' ISO script codes,
then the [=writing system=] is Japanese.
writing-system/writing-system-line-break-002.html
writing-system/writing-system-segment-break-001.html
If the [=content language=] is Korean and the [=writing system=] is unspecified,
or for any [=content language=]
if the [=writing system=] to specified to be one of the
''Kore'',
''Hang'',
or ''Jamo''
ISO script codes,
then the [=writing system=] is Korean.
The [=writing system=] is only considered
to be unknown
if the [=content language=] itself is unknown,
or if it explicitly indicates an unknown writing system.
Note: Mere omission of the [=writing system=] information
when the [=content language=] is declared
means the that the [=writing system=] is implied, not unknown.
This appendix is normative.
A few operations in this specification
depend on automated
word boundary detection
or
phrase boundary detection.
Both operations are similar:
the user agent performs linguistic analysis of the text
to identify language-specific meaningful sequences of characters.
They differ only targetting different units of text:
either words or phrases.
While easily understood in a broad sense,
both concepts of word and phrase are difficult to precisely define,
especially in a way that works accross multiple languages.
Nonetheless, in this context:
A word is a recognizable semantic unit which may comprise one or more characters or syllables.
Note: See What is a word?
for some discussion of this concept.
A phrase is a short grouping of one or several words
standing together as a conceptual or grammatical unit,
forming a component of a clause or sentence.
Note:
This is not to be confused with the French word phrase
which means sentence rather than phrase in the English sense used here.
In Japanese,
this corresponds to the concept of 文節.
A phrase could be
a noun with its article and prepositions or postpositions,
a phrasal verb,
a compound verb tense…
The start and end position of each detected word or phrase
is called a word boundary or phrase boundary.
By themselves, word and phrase boundaries are not observable,
but properties like 'word-space-transform' or 'word-break'
can cause visible effects at those positions.
The specific algorithm to detect word or phrases
and to place their boundaries is UA-dependent,
and may take into account a variety of factors or approaches,
such as
dictionary-based lexical analysis,
identification of punctuation or other delimiting characters,
morphological analysis,
machine learning methods…
The following constraints must nevertheless be respected:
The user agent must not place a word or phrase boundary
between characters that compose a single [=typographic character unit=].
The user agent must not place a word or phrase boundary
adjacent to any characters with the line breaking class GL, WJ, or ZWJ;
when two would-be words or phrases are separated by such characters,
they must be treated as a single one.
[[UAX14]]
word-space-transform/word-space-transform-024.html
word-space-transform/word-space-transform-025.html
word-space-transform/word-space-transform-026.html
word-break/auto-phrase/word-break-auto-phrase-003.html
word-break/auto-phrase/word-break-auto-phrase-004.html
word-break/auto-phrase/word-break-auto-phrase-005.html
If a word or phrase is immediately followed by one or more of the following characters,
the user agent must consider them to be part of the preceeding word or phrase:
[=word-separator characters=]
[=other space separators=]
U+200B ZERO WIDTH SPACE characters
Punctuation is not a phrase by itself:
it should to be attached to the relevant side of an adjacent linguistic word or phrase.
For example,
enclosing punctuation such as brackets and quotes
are part of the phrase they enclose;
commas and semicolons are suffixed to the preceding phrase;
U+00BF INVERTED QUESTION MARK is attached to the subsequent word;
etc.
However, unconventional use of punctuation,
such as smileys, kaomoji, or Perl snippets,
may cause the user agent to need to deviate from this principle.
Inline box boundaries
and out-of-flow elements must be ignored
when determining word or phrase boundaries.
However,
if a [=word boundary|word=] or [=phrase boundary=] is found at the same position as
one or more inline box boundaries,
the [=word boundary|word=] or [=phrase boundary=] must be inserted
in the outermost element that participates in this inline box boundary.
word-space-transform/word-space-transform-018.html
word-space-transform/word-space-transform-019.html
word-break/auto-phrase/word-break-auto-phrase-wbr-nobr-002.html
word-space-transform/word-space-transform-018.html
word-space-transform/word-space-transform-019.html
word-space-transform/word-space-transform-020.html
In the following example,
the red “|” indicates
reasonable positions for a user agent [=detecting word boundaries=] to place them:
กรุงเทพ|คือ|สวยงาม
If that sentence had contained some inline markup,
the following example shows the correct position to place the word boundaries:
กรุงเทพ|คือ|<em>สวยงาม</em>
The following example shows incorrect positions:
กรุงเทพ|คือ<em>|สวยงาม</em>
The following shows the correct positions in a more contrived situation:
กรุงเทพ|<b><u>คือ</u>|<em>สวยงาม</em></b>
Security Considerations
This specification introduces no new security considerations.
Privacy Considerations
This specification leaks the user’s installed hyphenation and line-breaking dictionaries.
Acknowledgements
This specification would not have been possible without the help from:
Addison Phillips,
Aharon Lanin,
Alan Stearns,
Ambrose Li,
Arnold Schrijver,
Arye Gittelman,
Ayman Aldahleh,
Ben Errez,
Bert Bos,
Chris Lilley,
Chris Pratley,
Chris Thrasher,
Chris Wilson,
Dave Hyatt,
David Baron,
Emilio Cobos Álvarez,
Eric LeVine,
Etan Wexler,
Frank Tang,
Håkon Wium Lie,
IM Mincheol,
Ian Hickson,
James Clark,
Javier Fernandez,
John Daggett,
Jonathan Kew,
Ken Lunde,
Laurie Anna Edlund,
Marcin Sawicki,
Martin Dürst,
Martin Heijdra,
Masafumi Yabe,
Masayasu Ishikawa,
Michael Jochimsen,
Michel Suignard,
Mike Bemford,
Myles Maxfield,
Nat McCully,
Paul Nelson,
Pierre-Anthony Lemieux,
Rahul Sonnad,
Randy Edmunds,
Richard Ishida,
Shinyu Murakami,
Stephen Deach,
Steve Zilles,
Takao Suzuki,
Tantek Çelik,
Xidorn Quan,
Yaniv Feinberg.
Changes
This draft is kept in sync with [[CSS-TEXT-3]], see [[css-text-3#changes]].
Changes specific to Level 4 are listed below.
Significant changes since the 29 May 2024 Working Draft include:
* None yet.
Significant changes since the 19 February 2024 Working Draft include:
* Renamed the 'text-spacing-trim' value trim-auto to ''trim-both''.
(Issue 10161)
* Loosened requirement about not changing lines for ''text-wrap-style: balance''
for cases with large numbers of lines.
(Issue 10186)
* Define interraction between ''text-wrap-style: balance'' and 'line-clamp'
(Issue 9310)
* Add the ''math-auto'' value for 'text-transform'.
(Issue 5386)
Significant changes since the 20 October 2023 Working Draft include:
* Restored accidentally deleted “and each line after a [=forced line break=]”
from definition of ''text-spacing-trim: space-first''.
(Issue 9532)
* Make ''text-spacing-trim/normal'' the initial value of 'text-spacing-trim'.
(Issue 9511)
* Change the end-of-line behavior of ''text-spacing-trim/space-first''.
(Issue 9736)
* ''text-spacing-trim/space-first'' applies after line-breaks.
(Issue 9532)
* Clarify details of fullwidth punctuation collapsing.
(Issue 9225)
* Prevent pre from inheriting hanging-punctuation by default with a user-agent style rule.
(Issue 9689)
Significant changes since the 29 March 2023 Working Draft include:
* Recast the 'text-wrap' property as a shorthand of two new properties,
'text-wrap-mode' and 'text-wrap-style',
and making 'text-wrap-mode' rather than 'text-wrap'
a longhand of the 'white-space' property.
* Updated [[#small-kana]] to Unicode 15.0.
(Issue 8442)
* Redesign of the ''word-break: auto-phrase'' ''word-break: manual'' features
(from an earlier attempt as a standalone word-boundary-detection property),
and add an ''word-space-transform/auto-phrase'' value to 'word-space-transform'
(since it can no longer depend on word-boundary-detection).
and update supporting related mechanics.
* Rename word-boundary-expansion to 'word-space-transform'
* Add ''trim-all'' to 'text-spacing-trim'.
(Issue 8482)
* Non-tailorable Unicode line breaking controls other than NBSP
take precedence over our rule about atomic inlines.
(Issue 8972)
line-breaking/line-breaking-atomic-003.html
line-breaking/line-breaking-atomic-004.html
line-breaking/line-breaking-atomic-005.html
line-breaking/line-breaking-atomic-006.html
line-breaking/line-breaking-replaced-002.html
line-breaking/line-breaking-replaced-003.html
line-breaking/line-breaking-atomic-010.html
line-breaking/line-breaking-atomic-011.html
line-breaking/line-breaking-atomic-012.html
line-breaking/line-breaking-atomic-013.html
line-breaking/line-breaking-atomic-014.html
line-breaking/line-breaking-atomic-015.html
line-breaking/line-breaking-atomic-016.html
line-breaking/line-breaking-atomic-017.html
line-breaking/line-breaking-atomic-018.html
line-breaking/line-breaking-atomic-019.html
line-breaking/line-breaking-atomic-020.html
line-breaking/line-breaking-atomic-021.html
line-breaking/line-breaking-atomic-022.html
line-breaking/line-breaking-atomic-023.html
line-breaking/line-breaking-atomic-024.html
line-breaking/line-breaking-atomic-025.html
line-breaking/line-breaking-atomic-026.html
line-breaking/line-breaking-atomic-027.html
Significant changes since the 1 March 2023 Working Draft include:
* Completed the translation of 'white-space' to multiple longhands by
* adding ''break-spaces'' to 'white-space-collapse' so that all shorthand values can be represented in the longhands
(Issue 8256)
* integrating all longhand keywords into the 'white-space' shorthand
* updating prose accordingly
* Renamed text-space-collapse and text-space-trim
to 'white-space-collapse' and 'white-space-trim'.
(Issue 8273)
Significant changes since the 31 December 2022 Working Draft include:
* Redesigned 'text-spacing' by:
* Removing non-useful keyword combinations
(Issues 4246,
8288)
* Making ''space-first'' the initial value
(Issue 2462)
* Splitting into longhands
(Issues 4246,
7183,
8288)
* Ensuring the ability to turn each feature “off”.
(Issues 6950,
8288)
* Add keywords to allow replacing incorrect space characters in the source.
(Issues 318,
7183,
8263)
* Allow 'hanging-punctuation' to hang leading ideographic spaces
to compensate for plaintext-derived source text practices.
(Issue 2462)
* Move ''no-compress'' to 'text-justify' since it controls justification more than spacing.
(Issue 7079)
* Extended contextual characters evaluated in 'text-spacing'
to include characters from the Pe and Ps categories.
(Issue 6091)
* Renamed text-space-collapse back to 'white-space-collapse'.
(Issue 8273)
Significant changes since the 5 May 2022 Working Draft include:
Added ''text-justify/ruby'' value to 'text-justify'.
(Issue 771Issue 779)
Switched ''text-spacing: normal'' to use ''text-spacing/trim-end'' instead of ''text-spacing/allow-end''.
(Issue 7055)
Switched ''text-spacing: normal'' to also apply ''text-spacing/ideograph-alpha'' and ''text-spacing/ideograph-numeric'',
updated UA default stylesheet to exclude these from monospace contexts,
specified that non-zero margin/border/padding inhibits space insertion,
and defined the amount of inserted space as ''0.125ic''.
(Issue 6950)
Defined ''text-align: match-parent'' to compute to ''text-align/start'' on the [=root element=]
for simplicity of implementation.
(Issue 6542)
Allow ''text-justify/distribute'' keyword to be a [=legacy value alias=]
or to simply compute to ''text-justify/inter-character'';
this allows UAs to do whichever is easier, since the distinction does not matter for backwards-compatibility.
(Issue 7322)
Renamed trim-inner value of 'white-space-trim' to ''discard-inner'' for consistency with other values.
(Issue 448)
Adding percentages to 'word-spacing' and 'letter-spacing'
to represent sizes relative to the current 'font-size'.
(Issue 2165)
Suggesting a UA rule to prevent spaces in <{textarea}> from collapsing.
(Issue 6309)
Additions Since Level 3
New features in Level 4:
* ''word-break: auto-phrase'', for automaticly determining phrases to keep together while line breaking
* 'word-space-transform', for transforming word separators
* breaking up of the 'white-space' property into multiple longhands:
* 'white-space-collapse' and its ''preserve-spaces'' and ''white-space-collapse/discard'' values
* 'white-space-trim', for trimming excess white space at the boundaries of an element
* 'text-wrap-mode' to control whether wrapping occurs or not
* 'text-wrap-style' and its ''balance'', ''stable'', and ''pretty'' values
* 'wrap-before', 'wrap-after', and 'wrap-inside', to avoid or force wrapping (similar to the 'break-*' properties for pagination)
* 'hyphenate-character', to explicitly control the hyphenation character
* 'hyphenate-limit-zone', 'hyphenate-limit-chars', 'hyphenate-limit-lines', 'hyphenate-limit-last', for better control over automatic hyphenation
* <> values for 'text-align' for aligning on, e.g., a decimal point
* 'text-group-align' for group-aligning a set of line boxes whose contents are aligned by 'text-align'
* 'line-padding' for inserting spaces within the inline box at the start/end of lines
* 'text-spacing' for automatic spacing around punctuation and script changes
text-stroke-width-subpixel.html
![[isolated DAL + isolated ALEF + initial MEEM +
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(CANADIAN SYLLABICS KA +
CANADIAN SYLLABICS SI +
CANADIAN SYLLABICS TA +
CANADIAN SYLLABICS NI +
CANADIAN SYLLABICS WEST-CREE WA +
CANADIAN SYLLABICS NI +
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CANADIAN SYLLABICS HYPHEN)](images/cree-before.svg)
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