CSS Mobile Profile 2.0

1. Introduction

This document specifies a profile of CSS that is in general based on CSS 2.1 [CSS21], but requires as well new features from CSS 3. In addition the document defines an OPTIONAL feature set, that is suggested to be implemented by more advanced user agents.

2. Conformance

The key words of descriptive assertions and RFC 2119 terminology. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119].

Since the goal of this specification is to define a baseline interoperability level, user agents MAY accept CSS documents conforming to CSS 2.1 or subsequent revisions of the CSS family of Recommendations.

In order to conform to this specification, user agents, authoring tools, and content MUST conform to the Conformance and Error conditions section of the CSS 2.1 specification [CSS21], with the following modifications.

Only features marked as supported in this specification are REQUIRED. Aside of the REQUIRED feature set, an additional OPTIONAL feature set is given, that may be implemented by more advanced user agents. This feature set is REQUIRED by the CDF as in [WICDMobile10]. Support for a larger set of CSS 2.1 is OPTIONAL.
The requirement concerning which CSS 2.1 media types are supported is tightened so that both the handheld and all media types MUST be accepted and processed. Other media types MAY be accepted and processed as well.
The requirements that user agents MUST make it possible to select an alternate style sheet amongst those linked from the document, as well as provide for a way to turn off author style sheets, are relaxed to be RECOMMENDED behavior, but not REQUIRED.

3. Selectors

Selectors are defined in the Selectors chapter of the CSS 2.1 specification [CSS21]. The following table identifies which selector constructs MUST be supported amongst those defined by CSS 2.1.

Selector type	Example	Meaning	Conformance
Universal selector	`*`	Matches any element.	REQUIRED
Type selectors	`E`	Matches any E element.	REQUIRED
Descendant selectors	`E F`	Matches any F element that is a descendant of an E element.	REQUIRED
Child selectors	`E > F`	Matches any F element that is a child of an element E.	REQUIRED
The link pseudo-classes	`E:link`	Matches element E if E is the source anchor of a hyperlink, unvisited by a user.	REQUIRED
The link pseudo-classes	`E:visited`	Matches element E if E is the source anchor of a hyperlink, visited by a user.	REQUIRED
The dynamic pseudo-classes	`E:active`	Matches element E if E is being activated by the user.	REQUIRED
The dynamic pseudo-classes	`E:focus`	Matches element E if E has the focus (accepts keyboard events or other forms of text input).	REQUIRED
Class selectors	`.warning`	Language specific. (In (X)HTML, matches elements whose `class` attribute contains a token with the same name.)	REQUIRED
ID selectors	`#myid`	Matches any element with an ID equal to "myid".	REQUIRED
Grouping	`E1, E2, E3 { ... }`	Matches a group of elements, which share the same style declarations.	REQUIRED

4. At-rules

At-rules are defined in the at-rules section of the CSS 2.1 specification [CSS21]. The following table identifies which at-rule constructs MUST be supported amongst those defined by CSS by setting the at-rule as REQUIRED in the table’s last column. Only at-rules that are part of the suggested feature set for advanced user agents are listed here as OPTIONAL.

Rule	Definition	Conformance
@charset	Defines character encoding for the style sheet.	REQUIRED
@import	Imports an external style sheet.	REQUIRED
@media	Groups a set of style rules to apply only to one or more particular media. Only the `handheld` and `all` media types MUST be accepted and processed. Other media types MAY be accepted and processed as well.	REQUIRED
@namespace	For declaring the default namespace and binding namespaces to namespace prefixes.	OPTIONAL

5. Properties

Properties are defined in several chapters of the CSS 2.1 specification [CSS21] and in case of marquee properties in the CSS Marquee Module [CSS3MARQUEE]. The following table identifies which properties MUST be supported amongst those defined by CSS by setting the property as REQUIRED in the table’s last column. Only properties that are part of the suggested feature set for advanced user agents are listed here as OPTIONAL. The property syntax is provided (expressed using the same value specifications as CSS 2.1) when it is subsetted from the original. Limitations that apply to a property apply equally to its shorthand alternative.

Property	Syntax (if different from CSS)	Conformance
background-color		REQUIRED
background-image		REQUIRED
background-repeat		REQUIRED
background-attachment		REQUIRED
background-position	`top \| center \| bottom \| left \| right \| inherit`	REQUIRED
background		REQUIRED
border-top-width border-right-width border-bottom-width border-left-width		REQUIRED
border-width		REQUIRED
border-top-color border-right-color border-bottom-color border-left-color		REQUIRED
border-color		REQUIRED
border-top-style border-right-style border-bottom-style border-left-style	`none \| solid \| dashed \| dotted \| inherit`	REQUIRED
border-style	`none \| solid \| dashed \| dotted \| inherit`	REQUIRED
border-top border-right border-bottom border-left		REQUIRED
border		REQUIRED
bottom		OPTIONAL
clear		REQUIRED
color		REQUIRED
display	`inline \| block \| list-item \| none \| inherit`	REQUIRED
float		REQUIRED
font-family		REQUIRED
font-style		REQUIRED
font-variant		REQUIRED
font-weight		REQUIRED
font-size	`<absolute-size> \| <relative-size> \| inherit`	REQUIRED
font		REQUIRED
height		REQUIRED
left		OPTIONAL
list-style-type	`disc \| circle \| square \| decimal \| lower-roman \| upper-roman \| lower-alpha \| upper-alpha \| none \| inherit`	REQUIRED
list-style-image		REQUIRED
list-style		REQUIRED
margin-top margin-right margin-bottom margin-left		REQUIRED
margin		REQUIRED
marquee-direction [CSS3MARQUEE]		REQUIRED
marquee-loop [CSS3MARQUEE]		REQUIRED
marquee-speed [CSS3MARQUEE]		REQUIRED
marquee-style [CSS3MARQUEE]		REQUIRED
max-height		REQUIRED
max-width		REQUIRED
min-height		REQUIRED
min-width		REQUIRED
outline-color		OPTIONAL
outline-style	`none \| solid \| dashed \| dotted \| inherit`	OPTIONAL
outline-width		OPTIONAL
outline		OPTIONAL
overflow [CSS21]	auto	REQUIRED
overflow-style [CSS3MARQUEE]	marquee	REQUIRED
padding-top padding-right padding-bottom padding-left		REQUIRED
padding		REQUIRED
position		OPTIONAL
right		OPTIONAL
text-indent		REQUIRED
text-align		REQUIRED
text-decoration	`none \| blink \|underline \| inherit`	REQUIRED
text-transform		REQUIRED
top		OPTIONAL
vertical-align	`top \| middle \| bottom \| baseline \| inherit`	REQUIRED
visibility		REQUIRED
white-space		REQUIRED
width		REQUIRED
z-index		OPTIONAL

Informative Notes

Content Providers will reach a larger and more satisfied audience by following Mobile Web Best Practices [MOBILE-BP] and CSS Techniques for Web Content Accessibility Guidelines [WCAG10-CSS-TECHS].
The OMA Wireless CSS 1.1 [WCSS11] introduced three extensions Marquee, Access Keys and Input. Those extensions are deprecated in OMA Wireless CSS 1.2 [WCSS12]. The Marquee functionality has been redefined by the marquee properties of the CSS 3 box model [CSS3MARQUEE]

6. Syntax

A user agent MUST support all value types defined in the Values section of the CSS 2.1 specification [CSS21], with the following exceptions:

Support for counter values is OPTIONAL
Support for CSS2 System Colors and User preferences for fonts is OPTIONAL.

Acknowledgments

The editors wish to thank the authors of the previous version of this document, Ted Wugofski (Openwave), Doug Dominiak (Openwave, formerly Motorola), Peter Stark (Ericsson), and Tapas Roy (Openwave), as well as the authors of the OMA Wireless CSS specifications and the CSS 2.1 specification. Furthermore, the editors want to thank the CDF WG for their participation on this specification.

Conformance

Document conventions

Conformance requirements are expressed with a combination of descriptive assertions and RFC 2119 terminology. The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the normative parts of this document are to be interpreted as described in RFC 2119. However, for readability, these words do not appear in all uppercase letters in this specification.

All of the text of this specification is normative except sections explicitly marked as non-normative, examples, and notes. [RFC2119]

Examples in this specification are introduced with the words “for example” or are set apart from the normative text with class="example", like this:

Informative notes begin with the word “Note” and are set apart from the normative text with class="note", like this:

Advisements are normative sections styled to evoke special attention and are set apart from other normative text with <strong class="advisement">, like this: UAs MUST provide an accessible alternative.

Conformance classes

A style sheet is conformant to this specification if all of its statements that use syntax defined in this module are valid according to the generic CSS grammar and the individual grammars of each feature defined in this module.

A renderer is conformant to this specification if, in addition to interpreting the style sheet as defined by the appropriate specifications, it supports all the features defined by this specification by parsing them correctly and rendering the document accordingly. However, the inability of a UA to correctly render a document due to limitations of the device does not make the UA non-conformant. (For example, a UA is not required to render color on a monochrome monitor.)

An authoring tool is conformant to this specification if it writes style sheets that are syntactically correct according to the generic CSS grammar and the individual grammars of each feature in this module, and meet all other conformance requirements of style sheets as described in this module.

Partial implementations

So that authors can exploit the forward-compatible parsing rules to assign fallback values, CSS renderers must treat as invalid (and ignore as appropriate) any at-rules, properties, property values, keywords, and other syntactic constructs for which they have no usable level of support. In particular, user agents must not selectively ignore unsupported component values and honor supported values in a single multi-value property declaration: if any value is considered invalid (as unsupported values must be), CSS requires that the entire declaration be ignored.

Implementations of Unstable and Proprietary Features

Non-experimental implementations

Once a specification reaches the Candidate Recommendation stage, non-experimental implementations are possible, and implementors should release an unprefixed implementation of any CR-level feature they can demonstrate to be correctly implemented according to spec.

To establish and maintain the interoperability of CSS across implementations, the CSS Working Group requests that non-experimental CSS renderers submit an implementation report (and, if necessary, the testcases used for that implementation report) to the W3C before releasing an unprefixed implementation of any CSS features. Testcases submitted to W3C are subject to review and correction by the CSS Working Group.

Further information on submitting testcases and implementation reports can be found from on the CSS Working Group’s website at http://www.w3.org/Style/CSS/Test/. Questions should be directed to the public-css-testsuite@w3.org mailing list.