This section is not normative.
Grid Layout is a layout model for CSS
that has powerful abilities to control the sizing and positioning
of boxes and their contents.
Grid Layout is optimized for 2-dimensional layouts:
those in which alignment of content is desired in both dimensions.
Representative Grid layout example
Although many layouts can be expressed with regular Grid Layout,
restricting items into a grid in both axes also makes it impossible
to express some common layouts on the Web.
This module defines a layout system that removes that restriction
so that items can be placed into Grid-like tracks in just one of the axes,
while stacking them one after another in the other axis.
Items are placed into the column (or row) with the most remaining space
based on the layout size of the items placed so far.
This module also extends CSS Grid
with this new grid item placement strategy
and CSS Box Alignment with new alignment features.
Background and Motivation
Waterfall Layout with Auto-placed Items
[=Masonry layout=], sometimes also called “waterfall layout”,
is a common Web design pattern where a number of items--
commonly images or short article summaries--
are placed one by one into columns
in a way that loosely resembles stone masonry.
Unlike [[CSS-MULTICOL-1|multi-column layout]],
where content is placed vertically in the first column
until it must spills over to the second column,
[=masonry layout=] selects a column for each new item
such that it is generally closer to the top of the layout than items placed later.
The Pinterest search results page exemplifies this layout:
Representative masonry layout example
Here, each item has a different height
(depending on the content and the width of the column),
and inspecting the DOM reveals
(as the visual content itself gives no indication of ordering)
that each item has been placed into the column with the smallest height so far.
This layout superficially looks similar to multi-column layout;
but it has the advantage that scrolling down
will naturally lead to "later" items in the layout
(that is, those less relevant in the search results).
It's not possible to achieve this layout using earlier CSS layout models,
unless you know up-front how tall each item will be,
or use JavaScript for content measurement or placement.
Using a [=masonry container=] together with ''grid-area/auto''-positioned items
yields this type of masonry layout.
One-dimensional Grid Layout
[=Grid layout=] allows for powerful track sizing and explicit placement in two axes,
but sometimes a layout only needs alignment of its items in one dimension.
Using a [=masonry container=] together with explicitly-positioned items
allows for this type of one-dimensional grid layout.
This example by Douglas Graham
uses explicit positioning to place each item into its assigned column;
but there are no rows.
Instead, items in each column stack one after the other.
This layout can't be duplicated in [=grid layout=]
because the “spanning” relationships among the items in adjacent columns
is not fixed: it depends on their relative heights
and whether the optional banner or advertisement items are included.
It also can't be duplicated in [=flex layout=]
because the source order of the items
(which is used for reading, sequential navigation, and one-column mobile phone layout)
goes back and forth between the two columns.
Comparison of one-column and two-column variants of a one-dimensional grid layout.
Value Definitions
This specification follows the CSS property definition conventions from [[!CSS2]]
using the 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.
Masonry Layout Model
Masonry layout
lays out items into pre-defined tracks similar to [=grid layout=] in one axis
(called the grid axis),
but flows them freely similar to [=flex layout=] in the other
(called the stacking axis).
Similar to [=grid layout=] and unlike [=flex layout=],
[=masonry layout=]’s auto-placement
distributes items across the tracks to keep the lengths of those tracks
as similar as possible.
[=Grid items=] are formed and [=blockified=]
exactly the same as in a regular [=grid container=].
(For clarity, [=grid items=] and [=grid tracks=] of a [=masonry container=]
can be referred to as masonry items
and masonry tracks.)
All CSS properties work the same as in a regular [=grid container=]
unless otherwise specified by this specification.
For example, 'order' can be used to specify a different layout order for the items.
Note: Subgrid items are supported,
but subgridding only occurs in the [=grid axis=];
see [[#subgrids]] for details.
A masonry container is a box whose contents participate in [=masonry layout=].
A [=masonry container=] is a column masonry container
if its [=stacking axis=] is the [=block axis=],
or a row masonry container
if its [=stacking axis=] is the [=inline axis=].
Comparing Masonry Containers
Column Masonry
grid-template-columns: 1fr 2fr 3fr;
Row Masonry
grid-template-rows: 1fr 2fr 3fr;
Reordering and Accessibility
Although [=masonry layout=] generally progresses in a forwards fashion
(placing the next item down or endward of the current item,
matching the natural "reading order"),
it can switch between these two in a seemingly arbitrary manner.
In simple cases, the 'item-slack' property can help reduce
the feeling of backtracking due to small sizing differences in the [=block axis=]
when laying out auto-placed items.
But when [[#masonry-layout-algorithm|auto-placement]] is mixed with [=definite position|explicit placement=] or spanning items,
some amount of backtracking may occur.
For example, in the following markup sample,
the fourth item is a spanner that doesn't fit
in the remaining empty column on the first line.
It ends up positioned into the into the first column,
which is the highest available space into which it will fit.
The next few items, which have a span of 1,
end up laying out “above” it in the empty column,
violating the natural reading order.
<section class=masonry>
<div class=item>1</div>
<div class=item>2</div>
<div class="item tall">3</div>
<div class="item wide">4</div>
<div class=item>5</div>
<div class=item>6</div>
<div class=item>7</div>
</section>
<style>
.masonry {
//FIXME display:masonry or something
grid-template-columns: repeat(5, auto);
}
.item { height: 50px; }
.item.wide { grid-column: span 3; }
.item.tall { height: 90px; }
</style>
Auto-placed masonry layout with mixed-height items and mixed span sizes
Similarly, items explicitly placed into specific tracks can leave gaps behind them,
into which subsequent auto-placed items can be placed visually out-of-order.
Authors should be aware of these possibilities
and design layouts where such backtracking is minimized
so that focus and reading order can be more easily followed.
Alternatively, if the items do not have an inherent order,
use the 'reading-flow' property to allow the UA to re-order the items
for reading and linear navigation.
ISSUE: Or should reordering be the default behavior for auto-placed items here?
Techniques for reducing backtracking include:
* Using appropriate values for 'item-slack',
i.e. values large enough to avoid gratuitous differentiation among similarly-sized tracks,
but not so large that meaningful differences get ignored.
* Using explicit placement in ways that help group related items together,
rather than ways that disrupt the natural order of items
* Avoiding the combination of mixed span sizes in the [=grid axis=]
and disparate item sizes in the [=stacking axis=],
which can cause items to get pulled out of order (see example above).
As with [=grid layout=] and [=flex layout=]
authors can use the 'order' property to re-order items;
the same caveats apply.
See [[css-grid-2#order-accessibility]]
and [[css-flexbox-1#order-accessibility]].
Establishing Masonry Layout
ISSUE(11593): We are still debating what syntactic switch establishes a [=masonry layout=].
Proposals so far include:
* ''display: masonry'' (or a synonym, such as ''display: stack'')
* ''item-pack: collapse'' (see 'item-pack')
* a collapse value for 'grid-template-rows'/'grid-template-columns',
indicating that axis as the [=stacking axis=] of a [=grid container=]
Masonry Track Specification
In the [=grid axis=],
the full power of [=grid layout=] is available for track specification:
* Track sizes, line names, and areas can be specified on the [=masonry container=]’s [=grid axis=],
just like in [=grid layout=].
* The [=explicit grid=] and [=implicit grid=] are formed in the same way as for a regular [=grid container=].
* Items can be [[#masonry-track-placement|placed]] against these grid templates just as in [=grid layout=].
However,
auto-placed items contribute sizing to all tracks,
not just the track into which they are ultimately placed;
see [[#track-sizing]].
Note: This is because auto-placed items must be laid out as they are placed,
so that each track knows how “full” it is
(and therefore which track should receive the next auto-placed item);
thus, the tracks themselves must already have a definite size
so that the items know their [=available space=] during layout.
Declaring Masonry Track Templates: the 'grid-template-*' properties
The 'grid-template-*' and 'grid-auto-rows'/'grid-auto-columns' properties
(and their shorthands)
apply in the [=grid axis=] of the [=masonry container=]
and establish tracks just as on regular [=grid containers=].
(They are ignored in the [=stacking axis=].)
ISSUE(10869): What should be the initial track listing?
Intrinsic Tracks and repeat()
ISSUE(10915): Should we allow auto-repeated content-based tracks?
Is this a reasonable definition for them?
Should they work also in Grid Layout somehow?
In Grid Layout,
all [=grid items=] are placed in the grid
before the grid tracks are sized.
This implies that ''repeat()/auto-fill''/''repeat()/auto-fit'' repetition
can't include intrinsically sized tracks such as ''grid-template-rows/auto''
(either in the ''repeat()'' function or alongside it
in the fixed portion of the track list),
as that would require the layout algorithm
to have already determined which items would go in those tracks,
to determine how large the tracks are,
to determine how many repetitions fit in the available space.
In Masonry Layout,
as [=masonry item=] placement and layout are intertwined and somewhat simplified,
this restriction is no longer strictly required.
It requires a slightly heuristic definition of sizing,
but auto repetition can include intrinsically-sized tracks
in a [=masonry container=]
(and the initial value of 'masonry-template-tracks' uses this!).
To determine the number of repetitions
that a ''repeat()'' function resolves to,
run layout as defined in [[#track-sizing-performance]],
with the following changes:
* Expand ''repeat()/auto-fill''/''repeat()/auto-fit'' repeat functions once.
* Ignore item placement.
(That is, assume all items have ''masonry-track: auto''.)
* If a [=masonry item=] has a span larger than 1,
then for each of its intrinsic sizes
that it would contribute to the [=virtual masonry item=],
first subtract the combined size of the gaps it would span,
and divide by its span.
Then treat it as being a span-1 item with those sizes.
Any intrinsically-sized tracks are then treated as having the size
calculated by this simplified layout
(including those in ''repeat()'' arguments,
taking from their corresponding single repetition)
for the purpose of determining how many repetitions
the ''repeat()'' functions resolve to.
Motivation
This simplified layout heuristic is defined to be "good enough",
while remaining fast and consistent.
Ignoring placement is required just to make the concept coherent;
before you know how many repetitions you need,
you can't tell what track an item with a definite placement
will end up in.
By chopping spanning items into span-1 items,
this avoids the possible need to expand a repeat() multiple times,
and the incoherent possibility of getting different sizes
for the same keyword across the repetitions.
It also makes the layout as a whole significantly cheaper,
as you only need to consider each unique track size;
you don't even really need to do any repeat() expansion.
That is, in ''auto repeat(auto-fill, min-content auto)'',
both of the ''grid-template-rows/auto'' keywords
will resolve to the same size under this heuristic layout;
you can just figure out what
a ''masonry-template-tracks: auto''
and ''masonry-template-tracks: min-content''
would each result in,
and use those sizes.
Subgrids
[=Subgridding=] allows nested [=masonry containers=] (and [=grid containers=])
to share track sizes.
If the parent's corresponding axis is a [=grid axis=],
the subgridded axis is taken from the parent container
[[css-grid-2#subgrids|as specified for grid containers]];
if the parent's corresponding axis is a [=stacking axis=],
the subgridded axis acts like ''masonry''.
Note: If this results in ''grid-template/masonry'' in both axes,
it is resolved as normal for [=masonry containers=] with double-axis ''grid-template/masonry'' templates,
i.e. it acts like ''grid-template-columns: none; grid-template-rows: masonry''.
In [=masonry layout=], auto-placed [=subgrids=]
don't inherit any line names from their parent grid,
because that would make the placement of the item
dependent on layout results;
but the subgrid's tracks are still aligned to the parent's tracks as usual.
```
The rendering of the subgrid example above.
Note how the subgrid's first item ("subgrid.1") contributes
to the intrinsic size of the 2nd row in the parent grid.
This is possible since the subgrid specified a definite position
so we know which tracks it will occupy.
Note also that trying to subgrid the parent's [=stacking axis=]
results in the subgrid getting [=masonry layout=] in its [=inline axis=].
A [=subgrid=] that is a [=masonry container=]
can be referred to as a submasonry.
Track Repetition: the ''repeat()'' notation
This specification introduces new keywords and masonry-specific behavior
for the ''repeat()'' notation.
repeat(auto-areas)
The new auto-areas value for the ''repeat()'' notation
represents the number of repetitions necessary
for the total number of explicit tracks to match
the 'grid-template-areas' / 'masonry-template-areas' value
in effect in the corresponding axis.
If multiple tracks are listed for the repetition,
the final repetition is truncated as necessary
to produce the correct number of tracks.
Note: Unlike ''repeat()/auto-fit''--
which always repeats at least once and always repeats the track listing entirely--
the number of repetitions for ''repeat()/auto-areas'' can be zero
(if there are already enough explicit tracks),
and the final repetition can be partial.
If 'grid-template-areas' / 'masonry-template-areas' is ''grid-template-areas/none'',
this value behaves as ''auto-fit''.
Note: This value applies both to regular [=grid containers=] and to [=masonry containers=].
ISSUE(10854): It's unclear if we actually need this value.
Note that the explicit grid already takes values from 'grid-auto-columns'/'grid-auto-rows'/'masonry-auto-tracks'
as needed to match the number of template areas.
repeat(auto-fit)
In [=masonry containers=] (as in regular [=grid containers=])
''repeat()/auto-fit'' acts like ''repeat()/auto-fill'',
but with empty tracks [=collapsed tracks|collapsed=].
However, because placement occurs after track sizing,
[=masonry containers=] use a heuristic
to determine if a track will be occupied:
* All tracks occupied by explicitly placed items are considered occupied.
* With the sum of the spans of all auto-placed items as N,
all unoccupied tracks up to the Nth such track
are considered occupied.
All tracks produced by the ''repeat()/auto-fit'' repetition and considered unoccupied by this heuristic
are assumed “empty” and are [=collapsed tracks|collapsed=].
A [=collapsed track=] cannot accept placement of auto-placed items.
Note: It is possible for an auto-placed item to be placed in a track when ''repeat()/auto-fill'' is used
that would be collapsed if ''repeat()/auto-fit'' is used
if there are auto-placed items with a span greater than 1
mixed with explicitly-placed items that leave gaps too small for the auto-placed items.
Grid Axis Track Sizing
Track sizing works the same as in [[css-grid-2#algo-track-sizing|CSS Grid]],
except that when considering which items contribute to intrinsic sizes:
* All items explicitly placed in that track contribute, and
* All items with an [=automatic grid position=] contribute
(regardless of whether they are ultimately placed in that track).
For example, suppose there are two columns in the [=grid axis=]
and that
* Items A, B, and C have no explicit position.
* Item D is explicitly placed into the first column.
In this case, items A, B, C, and D all contribute to sizing the first column,
while only A, B, and C (and not D) contribute to the second column.
In the case of spanning items with an [=automatic grid position=],
they are assumed to be placed at every possible start position,
and contribute accordingly.
For example, suppose there are 5 columns in the [=grid axis=],
with the middle having a fixed size of ''100px''
and the other two being ''grid-template/auto''-sized.
For the purpose of track sizing,
an item that spans 2 tracks
and has an intrinsic contribution of 220px
is essentially copied and assumed to exist:
* At grid line 1,
contributing 110px to each of the first two tracks.
* At grid line 2,
contributing 120px to the second track.
* At grid line 3,
contributing 120px to the fourth track.
* At grid line 4,
contributing 110px to the fourth and fifth tracks.
Note: This algorithm ensures that each track is at least big enough
to accommodate every item that is ultimately placed in it,
and does not create dependency cycles between placement and track sizing.
However, depending on the variation in sizes,
tracks could be larger than necessary:
an exact fit is only guaranteed if
all items are explicitly placed in the [=grid axis=]
or all items are the same size
(or matching multiples of that size, in the case of spanning items).
Subgrid Item Contributions
When sizing the tracks of either a regular [=grid container=] or a [=masonry container=],
a [=submasonry=] has special handling of items that have an [=automatic grid position=]:
* Any such item is placed into every possible grid track
that could be spanned by the [=submasonry=].
(If the submasonry has a [=definite grid position=], thus only the spanned tracks;
if it has an [=automatic grid position=], then all tracks in the parent grid.)
* Any such item receives the largest margin/border/padding contribution
of each edge at which it could hypothetically be placed.
If the item spans the entire subgrid, it receives both.
(See CSS Grid Layout §9.)
Optimized Track Sizing
Track sizing can be optimized by aggregating items
that have the same span size and placement
into a single virtual item
as follows:
Separate all the [=masonry items=] into item groups, according to the following properties:
* the span of the item
* the placement of the item,
i.e. which tracks it is allowed to be placed in
* the item's [=baseline-sharing group=]
Note: For example, an item with span 2 placed in the second track
will be in a different group than an item with span 2 that has an [=automatic grid position=].
For each [=item group=], synthesize a virtual masonry item
that has the maximum of every intrinsic size contribution
among the items in that group.
If the items apply [=baseline alignment=],
determine the baselines of the [=virtual masonry item=]
by placing all of its items into a single hypothetical grid track
and finding their shared baseline(s) and shims.
Increase the group's intrinsic size contributions accordingly.
Place hypothetical copies of each [=virtual masonry item=] into the [=grid axis=] tracks
in every position that the item could potentially occupy,
and run the [[css-grid-2#algo-track-sizing|track sizing algorithm]] with those items.
The resulting track sizes are the [=masonry container's=] track sizes.
Note: This optimization should give the same results
as the track sizing description [[#track-sizing|above]];
if not this is an error, please
report it to the CSSWG.
Masonry Placement
In the [=grid axis=],
items can be explicitly placed into tracks and span them using the familiar [=grid-placement properties=]’ syntax.
Auto-placement, however, uses the [[#masonry-layout-algorithm]],
placing each item with an [=automatic grid position=]
into the “shortest” masonry track available.
Here's a masonry layout example
demonstrating placed and spanning items:
Rendering of the example above.
ISSUE: Need a better example!!!
Specifying Masonry Item Placement: the 'grid-column-*' and 'grid-row-*' properties
The 'grid-column-*' and 'grid-row-*' properties
(and their shorthands)
apply in the [=grid axis=] of the items
and establish placement just as in regular [=grid layout=].
Placement Precision: the 'item-slack' property
Name: item-slack
Value: <> | infinite
Initial: 1em
Percentages: relative to the [=grid-axis=] [=content box=] size of the [=masonry container=]
Inherited: no
Applies to: [=masonry containers=]
Computed value: a computed <> value
Animation type: as length
[=Masonry containers=] are filled
by placing each [=masonry item=]
in whichever [=masonry track=] is currently the least filled.
When multiple tracks are tied for least-filled,
placing the items in order looks good.
But if tracks are only very slightly different heights,
it can look strange to have them not fill in order,
as the height differences aren't perceived as meaningfully different.
The 'item-slack' property specifies what the threshold is
for considering tracks to be “the same height”,
causing them to fill in order.
: <>
:: Specifies the tie threshold
for the [=masonry container=].
Placement positions are considered to be equally good (“tied”)
if they are within the specified distance
from the shortest position.
Note: The initial value is a “small” distance (''1em'')
that is probably appropriate to represent “close enough”.
: infinite
:: Specifies an infinite [=tie threshold=].
This makes items distribute themselves strictly in order,
without considering the length of the tracks at all.
Note: This value can result in consecutive items being placed
in dramatically different positions in the [=stacking axis=],
which can be confusing to readers.
If the initial value (`1em`) is too small,
consider a larger value (such as `10em` or `50vh`)
instead of `infinite`.
Issue: Is ''1em'' the right default?
Masonry Layout and Placement Algorithm
For each of the tracks in the [=grid axis=],
keep a running position initialized to zero.
Maintain also a auto-placement cursor,
initially pointing to the first line.
For each item in [=order-modified document order=]:
If the item has a [=definite grid position=] in the [=grid axis=],
use that placement.
ISSUE: Should this also update the placement cursor?
Otherwise, resolve its [=grid axis=] placement using these substeps:
Starting at the first [=grid axis=] line in the [=implicit grid=],
find the largest [=running position=] of the [=grid axis=] tracks
that the item would span if it were placed at this line,
and call this position max_pos.
Repeat the previous step for each successive line number
until the item would no longer fit inside the grid.
Let |possible lines| be the line that resulted in the smallest max_pos,
and all lines that result in a max_pos within the [=tie threshold=] of this max_pos.
Choose the first line in |possible lines| greater than or equal to the [=auto-placement cursor=]
as the item's position in the [=grid axis=];
or if there are none such, choose the first one.
Update the [=auto-placement cursor=] to point to item's last line.
Place the item in its [=grid axis=] tracks
at the maximum of the [=running position=]s
of the tracks it spans.
Calculate the size of the item's containing block
and then layout the item.
Set the [=running position=] of the spanned [=grid axis=] tracks
to max_pos + [=outer size=] + 'grid-gap'.
Note: This algorithm chooses the track
that would result in the item being placed as highly as possible.
If there are ties, it chooses the earliest such track,
after the most recently placed item if possible
(ensuring that it always “moves forward” even in the presence of ties).
Containing Block
The [=containing block=] for a [=grid item=] participating in [=masonry layout=]
is formed by its [=grid area=] in the [=grid axis=]
and the [=grid container=]'s [=content box=] in the [=stacking axis=].
Placement and Writing Modes
Note: Like all of [=grid layout=],
masonry layout and placement is sensitive to the [=writing mode=].
For example, for ''direction: rtl'',
items are placed right-to-left rather than left-to-right,
whether the inline axis is a [=grid axis=] or a [=stacking axis=].
Here's a simple example using ''direction: rtl'' in the [=grid axis=]:
```css
```
```html
1234
```
Rendering of the ''direction: rtl'' example above.
Here's a simple example
using ''direction: rtl'' in the [=stacking axis=]:
```css
```
```html
1234
```
Rendering of the ''direction: rtl'' example above.
Sizing Grid Containers
[[css-grid-2#intrinsic-sizes|Sizing Grid Containers]] works the same as for regular [=grid containers=]
but with the following addendum for the [=stacking axis=]:
The max-content size (min-content size) of a [=grid container=] in the [=stacking axis=]
is the size of the [=masonry box=] in that axis
when sized under a max-content constraint (min-content constraint).
```
Rendering of the [=grid container=] intrinsic sizing example above.
Alignment and Spacing
[[css-grid-2#gutters|Gutters]] are supported in both axes.
In the [=stacking axis=],
the gap is applied between the margin boxes of each pair of adjacent items.
Margins do not collapse in either axis.
In the [=grid axis=],
[[css-grid-2#alignment|alignment]]
works the same as in a regular [=grid container=].
In the [=stacking axis=],
[[css-align-3#content-distribution|content-distribution]] is applied
to the content as a whole, similarly to how it behaves in block containers.
More specifically, the alignment subject is the masonry box,
which is the smallest rectangle bounding
the [=margin boxes=] of all the [=grid items=].
The extent of the [=masonry box=] is indicated by the dashed border.
(Note that item 1 has a 5px bottom margin here.)
Note: There is only ever one alignment subject
for these properties in the [=stacking axis=],
so the unique 'align-content' / 'justify-content' values boil down to
''align-content/start'',
''align-content/center'',
''align-content/end'',
and [=baseline alignment=].
(The behavior of ''align-content/normal'' and ''align-content/stretch''
is identical to ''align-content/start'',
and the [=distributed alignment=] values behave as their [=fallback alignments=].)
If the [=grid items=] overflow
the [=grid container=]'s [=content box=] in the [=stacking axis=],
then the [=masonry box=] will be larger than the [=grid container=]'s [=content box=].
ISSUE: Should alignment in the stacking axis do something more sophisticated?
What should that be?
Baseline Alignment in the stacking axis
Item [=baseline alignment=] inside the [=grid axis=] tracks
works as usual for a regular [=grid container=],
and the [=grid container=]'s baseline is determined
the same as for a regular [=grid container=] in that axis.
[=Baseline alignment=] is not supported in the [=stacking axis=].
The first baseline set of the [=grid container=] in this axis
is generated from the [=alignment baseline=] of
the first [=grid item=] in the first occupied track,
and the last baseline set from the last [=grid item=] placed.
ISSUE: We could support baseline alignment in the first row. Do we want to?
ISSUE: Should the last baseline come from the last lowest item placed instead?
Fragmentation
Fragmentation in the stacking axis
Each [=grid axis=] track is fragmented independently in the [=stacking axis=].
If a [=grid item=] is fragmented,
or has a [=forced break=] before/after it,
then the [=running position=] for the tracks that it spans in the [=grid axis=]
are set to the size of the [=fragmentainer=]
so that no further items will be placed in those tracks.
An item that is split into multiple fragments
retains its placement in the [=grid axis=] for all its fragments.
A grid item that is pushed, however,
is placed again by the next [=grid container=] fragment.
Placement continues until all items are placed or pushed to a new fragment.
Here's an example
illustrating fragmentation of a grid with masonry layout in its [=block axis=].
It renders like this:
Visualization of fragmentation in a [=block-axis=] [=masonry layout=].
Fragmentation in the Grid Axis
Fragmentation in the [=grid axis=] with [=masonry layout=] in the other axis
is also supported.
In this case the fragmentation behaves more like in a regular [=grid container=];
however, there's a separate step to determine which [=grid-axis=] track
each item is placed into,
before fragmentation occurs.
Here's an example
illustrating fragmentation of a grid with [=masonry layout=] in its [=inline axis=].
In this case the breaks occurs between the [=grid-axis=] rows.
It renders like this:
Visualization of fragmentation in the [=block axis=] with [=inline-axis=] [=masonry layout=].
Absolute Positioning
[[css-grid-1#abspos-items|Grid-aligned absolute-positioned descendants]] are supported
in [=masonry containers=] just as for regular [=grid containers=];
however, in the [=stacking axis=] there exist only two lines (in addition to the ''grid-area/auto'' lines) for placement:
* line 1 (line -2) corresponds to the start edge of the [=masonry box=]
* line 2 (line -1) corresponds to the end edge of the [=masonry box=]
ISSUE: It might be useful to define a static position in the [=stacking axis=].
Maybe it could defined as the max (or min?) current [=running position=]
of the [=grid-axis=] tracks at that point? Or the end of the item before it?
Graceful Degradation
Typically, a masonry design can be expected to degrade quite nicely
in a UA that supports Grid layout but not masonry layout.
Here's an example
to illustrate this.
```css
display: grid;
//FIXME item-flow: collapse; /* ignored in UAs that don't support masonry layout */
grid-template-columns: 150px 100px 50px;
```
This creates a layout with three columns,
but will have "more gaps" in the [=block axis=] if the UA doesn't support masonry layout.
Here's what it looks like with Masonry support for comparison:
Rendering of the example in a UA with Masonry support.
Appendix A: Generic Layout Item Flow Controls: the 'item-*' properties
Issue: This section is likely to move to another spec,
such as [[css-display-4]],
since it affects multiple display types.
Multiple layout modes in CSS place their children
as atomic "items" organized into rows and/or colummns in their container,
and allow the author to configure their ordering and placement.
The 'item-*' properties provide generic controls for
these ordering and placement options,
encapsulating the layout-specific 'flex-flow' and 'grid-auto-flow' properties.
Overview of Item Flow Controls
Flow-oriented Proposal
Track-oriented Proposal
Value Space
Description
Existing flex property
Existing grid property
'item-direction'
'item-track'
auto | row | column | row-reverse | column-reverse
Controls whether items are placed into rows or columns,
and whether within those tracks they are ordered
start-to-end or end-to-start.
flex-direction
grid-auto-flow
'item-wrap'
'item-cross'
[ auto | nowrap | wrap ] || [ normal | reverse ] | wrap-reverse
Controls whether items are wrapped
in the axis opposite to that controled by the row/column property,
and if so if they are placed in start-to-end or end-to-start order.
flex-wrap
Introduced into 'grid-auto-flow' in this level.
'item-pack'
'item-pack'
normal | dense || balance
Configures how items are packed into their tracks.
'grid-auto-flow'
'item-slack'
'item-slack'
normal | <> | infinite
Defines a layout-specific amount of "slack" in placement decisions.
ISSUE(11480): The CSSWG is still figuring out how these properties should be named and fit together.
Item Flow Axis: 'item-track'/'item-direction'
Name: item-direction, item-track
Value: auto | row | column | row-reverse | column-reverse
Initial: auto
Percentages: N/A
Inherited: no
Applies to: [=flex containers=], [=grid containers=], [=masonry containers=]
Computed value: as specified
Animation type: discrete
This property controls whether items are placed as rows or columns,
and whether within those tracks they are ordered
start-to-end or end-to-start.
ISSUE(11480): There two open debates on this property:
a) what should it be called and
b) does it describe the primary direction of placement,
or the orientation of the tracks into which items are placed;
in other words, is the primary axis defined by this property
the primary placement axis or the primary track axis.
These are identical for [=flex layout=] and [=grid layout=],
but differ for [=masonry layout=] whose primary placement direction
is across its tracks.
: auto
::
Computes to either ''item-direction/row'' or ''item-direction/column''
depending on the layout mode:
* On [=flex containers=] and [=grid containers=],
computes to ''item-direction/row''.
* On [=masonry containers=],
if 'grid-template-rows' is not ''grid-template-columns/none''
and 'grid-template-columns' is ''grid-template-columns/none'',
computes to the value representing row tracks;
otherwise computes to the value representing column tracks.
: row
::
Track-oriented Option
Represents placement into rows,
i.e. tracks or lines parallel to the [=inline axis=].
Items fill those rows in start-to-end order.
Flow-oriented Option
Represents row-primary item placement,
i.e. placing items start-to-end in the [=inline axis=],
producing flex row lines in [=flex layout=],
and column grid tracks in [=masonry layout=].
: column
::
Track-oriented Option
Represents placement into columns,
i.e. tracks or lines parallel to the [=block axis=].
Items fill those columns in start-to-end order.
Flow-oriented Option
Represents column-primary item placement,
i.e. placing items start-to-end in the [=block axis=],
producing flex column lines in [=flex layout=],
and row grid tracks in [=masonry layout=].
: row-reverse
::
Same as ''item-direction/row'',
but using end-to-start placement order.
: column-reverse
::
Same as ''item-direction/column'',
but using end-to-start placement order.
Name: item-wrap, item-cross
Value: [ auto | nowrap | wrap ] || [ normal | reverse ] | wrap-reverse
Initial: auto
Percentages: N/A
Inherited: no
Applies to: [=flex containers=], [=grid containers=], [=masonry containers=]
Computed value: as specified
Animation type: discrete
Controls placement in the axis opposite to the [=primary axis=].
: auto
::
Computes to ''item-wrap/nowrap'' on [=flex containers=],
and ''item-wrap/wrap'' on everything else.
: nowrap
::
Items are placed in the [=primary placement axis=] forever,
even if they run out of room.
In [=flex layout=] this creates a [=single-line flex container=];
in [=grid layout=] this creates [=implicit grid track|implicit tracks=] in the [=primary placement axis=] as necessary.
: wrap
::
Items wrap when the [=primary placement axis=] runs out of space.
In [=flex layout=] this creates a [=multi-line flex container=];
in [=grid layout=] auto-placement algorithm moves to the next
row/column when it runs out of explicit tracks in the [=primary placement axis=].
: normal
::
Items are placed in start-to-end order
in the axis opposite to the [=primary track axis=].
In [=flex layout=] and [=grid layout=],
this controls the direction that new tracks
(flex lines or grid tracks)
are placed in.
In [=masonry layout=],
for track-oriented syntax this controls which track is selected
when several are tied for equal height;
for flow-oriented syntax this controls which direction
items fill their track in.
: reverse
::
Items are placed in end-to-start order
in the axis opposite to the [=primary track axis=].
: wrap-reverse
::
Computes to ''wrap reverse''.
Note: This value exists for consistency with the existing 'flex-wrap' value.
ISSUE(11480): The interpretation and naming of this property depends on
the interpretation of axes for 'item-direction'/'item-track'.
Item Placement Packing Mode: the 'item-pack' property
Name: item-pack
Value: normal | dense || balance
Initial: normal
Percentages: N/A
Inherited: no
Applies to: [=flex containers=], [=grid containers=], [=masonry containers=]
Computed value: as specified
Animation type: discrete
This property controls how items are distributed among the tracks
in a layout-specific way.
: normal
::
Uses the default packing strategy for the layout mode.
: dense
::
Allows backtracking to place items in earlier spaces that were skipped.
(Such spaces can exist because earlier items were too big for those spaces.)
For example,
in [=flex layout=] this allows placing items on earlier lines
that still have enough empty space left over.
: balance
::
In [=flex layout=],
this value balances the amount of content on each line
(including the last line),
similar to ''text-wrap-style: balance''.
ISSUE(11243): One of the proposals for switching into [=masonry layout=]
is to add a collapse value
to this 'item-pack' property.
ISSUE(9326):
Should dense packing apply to masonry?
It's much more expensive in masonry,
as you have to lay out the element in every possible gap spot
to see if it's short enough to fit;
Grid gets to just juggle some integers.
Item Placement Shorthand: the 'item-flow' shorthand
This [=shorthand property=] sets all its 'item-*' [=longhand properties=]
in a single declaration.
Acknowledgements
Thanks goes to Cameron McCormack who wrote a masonry layout explainer document
(from which was lifted the Background chapter) and presented it to the CSSWG,
and to Mats Palmgren who developed the original version of this specification.
Thanks also to everyone who provided feedback on the initial proposal for this feature.
Security Considerations
As a layout specification,
this spec introduces no new security considerations
beyond that exposed by CSS layout in general.
Privacy Considerations
As a layout specification,
this spec introduces no new privacy considerations
beyond that exposed by CSS layout in general.
Changes
Additions Since Level 2
The following features have been added since
Level 2:
Added [=masonry layout=].
Added the 'item-flow' property and its longhands,
as generic controls for item ordering and placement.
See [[#flow-control]].
(Issue 11480)
Recent Changes
The following changes have been made since the
3 October Working Draft:
* Dropped the masonry-specific track template and placement properties.
(Issue 11243)
* Introduced 'item-flow' and the 'item-*' longhands,
replacing masonry-flow and related properties.
(Issue 11480)
* Renamed masonry-slack to 'item-slack'.
alignment/masonry-align-content-001.html
alignment/masonry-align-content-002.html
alignment/masonry-align-content-003.html
alignment/masonry-align-content-004.html
alignment/masonry-justify-content-001.html
alignment/masonry-justify-content-002.html
alignment/masonry-justify-content-003.html
alignment/masonry-justify-content-004.html
baseline/masonry-grid-item-content-baseline-001.html
baseline/masonry-grid-item-self-baseline-001.html
baseline/masonry-grid-item-self-baseline-002a.html
baseline/masonry-grid-item-self-baseline-002b.html
fragmentation/masonry-fragmentation-001.html
fragmentation/masonry-fragmentation-002.html
fragmentation/masonry-fragmentation-003.html
gap/masonry-gap-001.html
gap/masonry-gap-002.html
grid-placement/masonry-grid-placement-named-lines-001.html
grid-placement/masonry-grid-placement-named-lines-002.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-001-auto.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-001-fr.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-001-mix1.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-001-mix2.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-002-auto.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-002-fr.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-002-mix1.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-002-mix2.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-003-auto.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-003-fr.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-003-mix1.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-003-mix2.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-004-auto.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-004-fr.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-004-mix1.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-004-mix2.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-005.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-006.html
intrinsic-sizing/masonry-intrinsic-sizing-cols-007.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-001-auto.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-001-fr.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-001-mix1.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-001-mix2.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-002-auto.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-002-fr.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-002-mix1.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-002-mix2.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-003-auto.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-003-fr.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-003-mix1.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-003-mix2.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-004-auto.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-004-fr.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-004-mix1.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-004-mix2.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-005.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-006.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-007-ref.html
intrinsic-sizing/masonry-intrinsic-sizing-rows-007.html
item-placement/masonry-item-placement-001.html
item-placement/masonry-item-placement-002.html
item-placement/masonry-item-placement-003.html
item-placement/masonry-item-placement-004.html
item-placement/masonry-item-placement-005.html
item-placement/masonry-item-placement-006.html
item-placement/masonry-item-placement-007.html
item-placement/masonry-item-placement-008.html
item-placement/masonry-rows-item-placement-auto-flow-next-001.html
item-placement/masonry-rows-with-grid-width-changed.html
masonry-columns-item-containing-block-is-grid-content-width.html
masonry-grid-template-columns-computed-withcontent.html
masonry-not-inhibited-001.html
order/masonry-order-001.html
order/masonry-order-002.html
parsing/masonry-parsing.html
subgrid/masonry-subgrid-001.html
subgrid/masonry-subgrid-002.html
subgrid/track-sizing/masonry-subgrid-flex.html
subgrid/track-sizing/masonry-subgrid-intrinsic-sizing.html
subgrid/track-sizing/masonry-subgrid.html
track-sizing/masonry-track-sizing-check-grid-height-on-resize.html
track-sizing/masonry-track-sizing-explicit-block.html
track-sizing/masonry-track-sizing-overflow-left-side.html
track-sizing/masonry-track-sizing-overflow-right-side.html
track-sizing/masonry-track-sizing-span-row.html
