Abstract
This module contains the features of CSS relating to the alignment of boxes within their containers in the various CSS box layout models: block layout, table layout, flex layout, and grid layout. (The alignment of text and inline-level content is defined in [CSS3TEXT] and [CSS3LINE].)
CSS is a language for describing the rendering of structured documents
(such as HTML and XML)
on screen, on paper, in speech, etc.
Status of this document
This is a public copy of the editors’ draft.
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(part of the Style Activity).
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Table of contents
- 1
Introduction
- 2
Overview of Alignment Properties
- 3
Alignment Values
- 3.1
Positional Alignment: the center, stretch, start, end, self-start, self-end, flex-start, flex-end, left, and right keywords
- 3.2
Baseline Alignment: the baseline keyword
- 3.3
Distributed Alignment: the space-between, space-around, and space-evenly keywords
- 3.4
Overflow Alignment: the safe and true keywords
- 4
Content Distribution: the justify-content and align-content properties
- 5
Self-Alignment: Aligning the Box within its Parent
- 6
Default Alignment
- 7
Changes
-
Acknowledgments
-
Conformance
-
References
-
Index
-
Property index
- Issues Index
1
Introduction
This section is not normative.
CSS Levels 1 and 2 allowed for the alignment of text via text-align and
the alignment of blocks by balancing auto margins. However, except in
table cells, vertical alignment was not possible. As CSS3 adds further
capabilities, the ability to align boxes in various dimensions becomes more
critical. This module attempts to create a cohesive and common box alignment
model to share among all of CSS.
Note: The alignment of text and inline-level content is defined in [CSS3TEXT] and [CSS3LINE].
Inspiration for this document:
1.1
Module interactions
This module adds some new alignment capabilities to the block layout
model described in [CSS21] chapters 9 and 10 and defines the interaction
of these properties with the alignment of table cell content using
vertical-align, as defined in [CSS21] chapter 17.
The interaction of these properties with
Grid Layout [CSS3-GRID-LAYOUT]
and Flexible Box Layout [CSS3-FLEXBOX]
is defined in their respective modules.
No properties in this module apply to the ::first-line or
::first-letter pseudo-elements.
1.2
Values
This specification follows the
CSS property
definition conventions from [CSS21]. Value types not defined in
this specification are defined in CSS Level 2 Revision 1 [CSS21].
Other CSS modules may expand the definitions of these value types: for
example [CSS3VAL], when combined with this module, adds the
initial keyword as a possible property value.
In addition to the property-specific values listed in their definitions,
all properties defined in this specification also accept the
inherit
keyword as their property value. For readability it has not been repeated
explicitly.
2
Overview of Alignment Properties
The alignment properties in CSS can be described along two axes:
- which dimension they apply to (inline vs. stacking), and
- whether they control the position of the box within its parent, or the box’s content within itself.
Note: This proposal uses the terms “justify” and “align” to distinguish
between alignment in the inline and stacking dimensions, respectively.
The choice is somewhat arbitrary, but having the two terms allows for
a consistent naming scheme that works across all of CSS’s layout models.
The following table summarizes the proposed alignment properties
and the display types they can apply to.
| Common
| Axis
| Aligns
| Applies to
|
| justify-content
| inline
|
content within element
(effectively adjusts padding)
| block containers and flex containers
|
| align-content
| stacking
| block containers and flex containers
|
| justify-self
| inline
|
element within parent
(effectively adjusts margins)
| block-level elements and grid items
|
| align-self
| stacking
| flex items and grid items
|
| justify-items
| inline
|
items inside element
(controls child items’ align/justify-self: auto)
| grid containers
|
| align-items
| stacking
| flex containers and grid containers
|
The exact definition of these properties
outside what’s what’s defined in Flexbox
is still being worked out.
This is a second Working Draft
and is NOT STABLE.
Note: The *-items values don’t affect the element itself.
When set on a flex container or grid container,
they specify the interpretation of any align/justify-self: auto used on the items in the container element.
3
Alignment Values
All of the alignment properties use a common set of values,
defined below.
- alignment subject
-
The alignment subject is the thing or things being aligned by the property.
For justify-self and align-self,
the alignment subject is the margin box of the box the property is set on.
For justify-content and align-content,
the alignment subject is defined by the layout mode.
- alignment container
-
The alignment container is the rectangle that the alignment subject is aligned within.
This is defined by the layout mode,
but is usually the alignment subject’s containing block.
The positional alignment keywords specify a position for an alignment subject
with respect to its alignment container.
The <item-position> set of values is used by justify-self and align-self
to align the box within its alignment container,
and also by justify-items and align-items
(to specify default values for justify-self and align-self).
The <content-position> set of values is used by justify-content and align-content
to align the box’s contents within itself.
<item-position> = center | start | end | self-start | self-end |
flex-start | flex-end | left | right;
<content-position> = center | start | end | flex-start | flex-end | left | right;
Values have the following meanings:
- center
- Centers the alignment subject within its alignment container.
- start
- Aligns the alignment subject to be flush with the alignment container’s start edge.
- end
- Aligns the alignment subject to be flush with the alignment container’s end edge.
- self-start
- Aligns the alignment subject to be flush with the edge of the alignment container
corresponding to the alignment subject’s start side.
If the writing modes of the alignment subject and the alignment container are orthogonal,
this value computes to start.
- self-end
- Aligns the alignment subject to be flush with the edge of the alignment container
corresponding to the alignment subject’s end side.
If the writing modes of the alignment subject and the alignment container are orthogonal,
this value computes to end.
- flex-start
- Only used in flex layout. [CSS3-FLEXBOX]
Aligns the alignment subject to be flush with the edge of the alignment container
corresponding to the flex container’s main-start or cross-start side, as appropriate.
When used in layout modes other than Flexbox,
this value computes to start.
- flex-end
- Only used in flex layout.
Aligns the alignment subject to be flush with the edge of the alignment container
corresponding to the flex container’s main-end or cross-end side, as appropriate.
When used in layout modes other than Flexbox,
this value computes to end.
- left
- Aligns the alignment subject to be flush with the alignment container’s line-left edge.
If the property’s axis is not parallel with the inline axis,
this value computes to start.
- right
- Aligns the alignment subject to be flush with the alignment container’s line-right edge.
If the property’s axis is not parallel with the inline axis,
this value computes to start.
Add example images.
3.2
Baseline Alignment: the baseline keyword
Baseline alignment is a form of positional alignment
that relies on aligning the baselines of related alignment subjects
to each other.
- baseline
-
For table cells, grid items, and flex items, aligns the
cell/item’s first formatted line's baseline, if any,
with the same baseline in other baseline-aligned cells/items in the row/column (as appropriate for the axis).
In the case of align-content/justify-content,
this shifts the content of the box within it,
and may also affect its sizing.
In the case of align-self/justify-self
this shifts the entire box within its container,
and may affect the sizing of its container.
If the alignment subject’s position is not fully determined by baseline alignment,
the content is start-aligned insofar as possible while preserving the baseline alignment.
(Content that has no first-line baseline is thus start-aligned.)
Add example images.
3.2.1
Determining the Baseline of a Box
The baseline of a box is determined differently based on the layout model, as follow:
- block
- list-item
-
The inline-axis baseline of a block is the baseline of the first in-flow line box in the block,
or the first in-flow block-level child in the block that has a baseline,
whichever comes first.
If there is no such line box or child,
then the block has no baseline.
For the purposes of finding a baseline,
in-flow boxes with a scrolling mechanisms (see the overflow property)
must be considered as if scrolled to their origin position.
A block has no block-axis baseline.
- table
-
The inline-axis baseline of a table box is the baseline of its first row.
However, when calculating the baseline of an inline-block,
table boxes must be skipped.
The block-axis baseline of a table is undefined.
Or does it have no baseline?
Or is it based on its first column?
- table-row
-
If any cells in the row participate in its baseline alignment,
the inline-axis baseline of the row is their baseline,
after baseline alignment has been performed.
Otherwise, the inline-axis baseline of the row is the bottom content edge of the lowest cell in the row.
[CSS21]
A table row has no block-axis baseline.
- table-cell
-
The inline-axis baseline of a table cell is the baseline of the first in-flow line box in the cell,
or the first in-flow element that contributes a baseline in that axis,
whichever comes first.
A table cell has no block-axis baseline.
- flex
-
See Flex Baselines in [CSS3-FLEXBOX].
- grid
-
See Grid Baselines in [CSS3-GRID-LAYOUT].
Maybe these things are wrong?
CSS 2.1 is really weird about baseline alignment.
This whole section needs to be better defined and reviewed.
The distribution values are used by justify-content and align-content
to distribute the items in the alignment subject
evenly between the start and end edges of the alignment container.
When the alignment subject cannot be distributed in this way,
they behave as their fallback alignment.
Each distribution value has an associated <content-position> as a fallback alignment,
but one can alternatively be explicitly specified in the property.
<content-distribution> = space-between | space-around | space-evenly | stretch
- space-between
-
The items are evenly distributed in the alignment container.
The first item is placed flush with the start edge of the alignment container,
the last item is placed flush with the end edge of the alignment container,
and the remaining items are distributed so that the spacing between any two adjacent items is the same.
Unless otherwise specified,
this value falls back to start.
- space-around
-
The items are evenly distributed in the alignment container,
with a half-size space on either end.
The items are distributed so that the spacing between any two adjacent items is the same,
and the spacing before the first and after the last item is half the size of the other spacing.
Unless otherwise specified,
this value falls back to center.
- space-evenly
-
The items are evenly distributed in the alignment container,
with a full-size space on either end.
The items are distributed so that the spacing between any two adjacent items,
before the first item,
and after the last item
is the same.
Unless otherwise specified,
this value falls back to center.
- stretch
-
If the combined size of the items is less than the size of the alignment container,
any auto-sized items have their size increased equally so that the combined size exactly fills the alignment container.
Otherwise,
or if there are no auto-sized items,
this value is identical to flex-start.
(For layout modes other than flex layout, flex-start is identical to start.)
Add example images.
3.4
Overflow Alignment: the safe and true keywords
When the alignment subject is larger than the alignment container,
it will overflow.
Some alignment modes, if honored in this situation,
may cause data loss:
for example, if the contents of a sidebar are centered,
when they overflow they may send part of their boxes past the viewport’s start edge,
which can’t be scrolled to.
To help combat this problem,
an overflow alignment mode can be explicitly specified.
"True" alignment honors the specified alignment mode in overflow situations, even if it causes data loss,
while "safe" alignment changes the alignment mode in overflow situations in an attempt to avoid data loss.
If the overflow alignment isn’t explicitly specified,
the default overflow alignment is determined by the layout mode.
Document-centric layout modes, such as block layout, default to "safe" overflow alignment,
while design-centric layout modes, such as flex layout, default to "true" overflow alignment.
<overflow-position> = true | safe
- safe
-
If the size of the alignment subject overflows the alignment container,
the alignment subject is instead aligned as if the alignment mode were start.
- true
-
Regardless of the relative sizes of the alignment subject and alignment container,
the given alignment value is honored.
Transplant example 10 from flexbox.
The justify-content and align-content properties control alignment of the box’s content within the box.
Aligns the contents of the box as a whole along the box’s inline/row/main axis.
Values other than auto are defined above.
If both a <item-position> and <content-position> are given,
the second value represents an explicit fallback alignment.
- Block Containers:
-
The alignment container is the block container’s content box.
The alignment subject is the entire contents of the block.
The align-content property applies along the block axis,
but if a <content-distribution> is specified
the fallback alignment is used instead.
The justify-content property does not apply to and has no effect on block containers.
All values other than auto force the block container to establish a new formatting context.
For table cells, the behavior of the auto depends on the computed value of vertical-align:
top makes it behave as start,
middle makes it behave as center,
bottom makes it behave as end,
and all other values make it behave as baseline.
auto otherwise behaves as start.
- Multicol Layout:
-
The alignment container is the multi-column element’s content box.
The alignment subject is the column boxes, as a unit.
The align-content property applies along the block axis,
but if a <content-distribution> is specified
the fallback alignment is used instead.
The justify-content property does not apply to and has no effect on multi-column elements.
auto behaves as start.
- Flex Containers:
-
auto computes to stretch.
The alignment container is the flex container’s content box.
For justify-content, the alignment subject is the flex items in each flex line;
for align-content, the alignment subject is the flex lines.
The align-content property applies along the cross axis.
The justify-content property applies along the main axis,
but stretch behaves as start.
See [CSS3-FLEXBOX] for details.
- Grid Containers:
-
auto computes to start, and stretch behaves like start.
The alignment container is the grid container’s content box.
The alignment subject is the bounds of the grid.
Need to dfn a better term for this in Grid.
The align-content property applies along the block (column) axis.
The justify-content property applies along the inline (row) axis.
In both properties, if a <content-distribution> is specified,
the fallback alignment is used instead.
4.1
Baseline Content-Alignment
The content of boxes participating in row-like layout contexts can be baseline-aligned to each other.
The alignment subject of a box participating in baseline content-alignment
is shifted such that the baseline of the first formatted line of all participating boxes align,
and the intrinsic size of each box is increased
by the distance the content needed to shift
in order to thus align the baselines.
The set of boxes that participate in baseline content-alignment together depends on the layout model:
- Table Cells:
-
A table cell participates in baseline content-alignment
in either its row or column (whichever matches its inline axis)
if its computed align-content is baseline.
- Flex Items:
-
A flex item participates in baseline content-alignment
in its flex line if
its computed align-content is baseline,
its computed align-self is stretch or start,
and its inline axis is parallel to the main axis.
- Grid Items:
-
A grid item participates in baseline content-alignment
in either its row or column (whichever matches its inline axis)
if its computed align-content is baseline,
and its computed align-self or justify-self (whichever affects its block axis) is stretch or start.
If a cell/item spans multiple rows or columns,
it participates in alignment within its start-most row/column only.
5
Self-Alignment: Aligning the Box within its Parent
The justify-self and align-self properties control alignment of the box within its containing block.
5.1
Inline/Main-Axis Alignment: the justify-self property
| Name: | justify-self |
|---|
| Value: | auto | stretch | baseline | [ <item-position> && <overflow-position>? ] |
|---|
| Initial: | auto |
|---|
| Applies to: | block-level boxes, absolutely-positioned boxes, and grid items |
|---|
| Inherited: | no |
|---|
| Media: | visual |
|---|
| Computed value: | specified value |
|---|
| Percentages: | n/a |
|---|
| Animatable: | no |
|---|
Justifies the box within its parent along the inline/row/main axis:
the box’s outer edges are aligned within its alignment container
as described by its alignment value.
The auto keyword computes to
stretch on absolutely-positioned elements,
and to the computed value of justify-items on the parent
(minus any legacy keywords) on all other boxes.
- Block-level Boxes:
-
The justify-self property applies along its containing block’s inline axis.
The alignment container is the block’s containing block
except that for block-level elements that establish a block formatting context
and are placed next to a float,
the alignment container is reduced by the space taken up by the float.
(Note: This is the legacy behavior of HTML align.)
The alignment subject is the block’s margin box.
The default overflow alignment is safe.
In terms of CSS2.1 block-level formatting [CSS21],
the rules for "over-constrained" computations in section 10.3.3
are ignored in favor of alignment as specified here
and the used value of the offset properties are not adjusted to correct for the over-constraint.
The stretch value is equivalent to start on block-level boxes.
This property does not apply to floats.
- Absolutely-positioned Boxes:
-
The justify-self property applies along its containing block’s inline axis.
When neither margin in this dimension is auto
and neither offset property in this dimension is auto,
values other than stretch cause non-replaced absolutely-positioned boxes
to use shrink-to-fit sizing for calculating auto measures,
and justify-self dictates alignment as follows:
The alignment container is the box’s containing block
as modified by the offset properties (top/right/bottom/left).
The alignment subject is the box’s margin box.
The default overflow alignment is safe.
In terms of CSS2.1 formatting [CSS21],
the rules for "over-constrained" computations in section 10.3.7
are ignored in favor of alignment as specified here
and the used value of the offset properties are not adjusted to correct for the over-constraint.
The stretch keyword is equivalent to start on replaced absolutely-positioned boxes.
(This is because CSS 2.1 does not stretch replaced elements to fit into fixed offsets.)
- Table Cells:
-
This property does not apply to table cells,
because their position and size is fully constrained by table layout.
- Flex Items:
-
This property does not apply to flex items,
because there is more than one item in the main axis.
See flex for stretching and justify-content for main-axis alignment. [CSS3-FLEXBOX]
- Grid Items:
-
The justify-self property applies along the grid’s row axis.
The alignment container is the grid cell.
The alignment subject is the grid item’s margin box.
The default overflow alignment is true.
Should we make stretch actually work on block-level/abspos replaced boxes?
To maintain legacy compat, this requires adding a new value (named normal?)
which has the current behavior of stretching non-replaced boxes and start-aligning replaced ones.
The effect of these rules is that an auto-sized block-level table,
for example, can be aligned while still having side margins.
If the table’s max-content size is narrower than its containing block,
then it is shrink-wrapped to that size and aligned as specified.
If the table’s max-content size is wider, then it fills its containing block,
and the margins provide appropriate spacing from the containing block edges.
5.2
Block/Cross-Axis Alignment: the align-self property
Aligns the box within its parent along the block/column/cross axis:
the box’s outer edges are aligned within its alignment container
as described by its alignment value.
The auto keyword computes to
stretch on absolutely-positioned elements,
and to the computed value of align-items on the parent
(minus any legacy keywords) on all other boxes.
- Block-level Boxes:
-
The align-self property does not apply to block-level boxes
(including floats),
because there is more than one item in the block axis.
- Absolutely-positioned Boxes:
-
The justify-self property applies along its containing block’s inline axis.
When neither margin in this dimension is auto
and neither offset property in this dimension is auto,
values other than stretch cause non-replaced absolutely-positioned boxes
to use shrink-to-fit sizing for calculating auto measures,
and align-self dictates alignment as follows:
The alignment container is the box’s containing block
as modified by the offset properties (top/right/bottom/left).
The alignment subject is the box’s margin box.
The default overflow alignment is safe.
In terms of CSS2.1 formatting [CSS21],
the rules for "over-constrained" computations in section 10.6.4
are ignored in favor of alignment as specified here
and the used value of the offset properties are not adjusted to correct for the over-constraint.
The stretch keyword is equivalent to start on replaced absolutely-positioned boxes.
(This is because CSS 2.1 does not stretch replaced elements to fit into fixed offsets.)
- Table Cells:
-
This property does not apply to table cells,
because their position and size is fully constrained by table layout.
- Flex Items:
-
The align-self property applies along the flexbox’s cross axis.
The alignment container is the flex line the item is in.
The alignment subject is the flex item’s margin box.
The default overflow alignment is true.
See [CSS3-FLEXBOX] for details.
- Grid Items:
-
The align-self property applies along the grid’s column axis.
The alignment container is the grid cell.
The alignment subject is the grid item’s margin box.
The default overflow alignment is true.
5.3
Baseline Self-Alignment
Boxes participating in row-like layout contexts can be baseline-aligned to each other.
An alignment subject participating in baseline content-alignment
is shifted such that the baseline of the first formatted line of all participating boxes align,
and the intrinsic size of its alignment container is increased
by the largest distance a box needed to shift
in order to thus align the baselines.
The set of boxes that participate in baseline self-alignment together depends on the layout model:
- Flex Items:
-
A flex item participates in baseline content-alignment
if its inline axis is parallel to the main axis.
See [CSS3-FLEXBOX] for details.
- Grid Items:
-
A grid item participates in baseline content-alignment
in either its row or column (whichever matches its inline axis)
if its justify-self or align-self property (whichever matches its inline axis)
computes to baseline.
If a cell/item spans multiple rows or columns,
it participates in alignment within its start-most row/column only.
6
Default Alignment
The align-items and justify-items properties set the default align-self and justify-self behavior of the items contained by the element.
6.1
Inline/Main-Axis Alignment: the justify-items property
This property specifies the default justify-self for all of the boxes
(including anonymous boxes)
participating in this box’s formatting context.
Values have the following meanings:
- auto
-
If the inherited value of justify-items includes the legacy keyword,
auto computes to the the inherited value.
Otherwise, auto computes to:
- stretch for flex containers and grid containers
- start for everything else
- legacy
-
This keyword causes the value to effectively inherit into descendants.
It can only be combined with the center, left, and right positions.
The alignment keyword, but not the legacy keyword, is passed to justify-self.
It exists to implement the legacy alignment behavior of HTML’s
<center> element and align attribute.
Other values have no special handling and are merely passed to justify-self.
6.2
Block/Cross-Axis Alignment: the align-items property
This property specifies the default align-self for all of the boxes
(including anonymous boxes)
participating in this box’s formatting context.
Values have the following meanings:
- auto
-
Computes to:
- stretch for flex containers and grid containers
- start for everything else
Other values have no special handling and are merely passed to align-self.
7
Changes
Changes since the First Public Working Draft include:
Acknowledgments
Special thanks goes to Markus Mielke, Alex Mogilevsky, and the
participants in the CSSWG’s March 2008 F2F alignment discussions.
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:
This is an example of an informative example.
Informative notes begin with the word "Note" and are set apart from the
normative text with class="note", like this:
Note, this is an informative note.
Conformance to this specification
is defined for three conformance classes:
- style sheet
- A CSS
style sheet.
- renderer
- A UA
that interprets the semantics of a style sheet and renders
documents that use them.
- authoring tool
- A UA
that writes a style sheet.
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.
Experimental implementations
To avoid clashes with future CSS features, the CSS2.1 specification
reserves a prefixed
syntax for proprietary and experimental extensions to CSS.
Prior to a specification reaching the Candidate Recommendation stage
in the W3C process, all implementations of a CSS feature are considered
experimental. The CSS Working Group recommends that implementations
use a vendor-prefixed syntax for such features, including those in
W3C Working Drafts. This avoids incompatibilities with future changes
in the draft.
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.
References
Normative References
Index
- align-content, 4
- align-items, 6.2
- alignment container, 3
- alignment subject, 3
- align-self, 5.2
- auto
- value for justify-content,, align-content, 4
- value for justify-self, 5.1
- value for align-self, 5.2
- value for justify-items, 6.1
- value for align-items, 6.2
- baseline, 3.2
- baseline content-alignment, 4.1
- baseline self-alignment, 5.3
- center, 3.1
- <content-distribution>, 3.3
- <content-position>, 3.1
- end, 3.1
- fallback alignment, 3.3
- flex-end, 3.1
- flex-start, 3.1
- <item-position>, 3.1
- justify-content, 4
- justify-items, 6.1
- justify-self, 5.1
- left, 3.1
- legacy, 6.1
- overflow alignment, 3.4
- <overflow-position>, 3.4
- right, 3.1
- safe, 3.4
- self-end, 3.1
- self-start, 3.1
- space-around, 3.3
- space-between, 3.3
- space-evenly, 3.3
- start, 3.1
- stretch, 3.3
- true, 3.4
Property index
| Name | Value | Initial | Applies to | Inh. | %ages | Media | Animatable | Computed value |
|---|
| justify-content | auto | baseline | [ <item-position> <content-position>? | <content-position> ] && <overflow-position>? | auto | block containers, flex containers, and grid containers | no | n/a | visual | no | specified value
|
|---|
| align-content | auto | baseline | [ <item-position> <content-position>? | <content-position> ] && <overflow-position>? | auto | block containers, flex containers, and grid containers | no | n/a | visual | no | specified value
|
|---|
| justify-self | auto | stretch | baseline | [ <item-position> && <overflow-position>? ] | auto | block-level boxes, absolutely-positioned boxes, and grid items | no | n/a | visual | no | specified value
|
|---|
| align-self | auto | stretch | baseline | [ <item-position> && <overflow-position>? ] | auto | block-level boxes | no | n/a | visual | no | specified value
|
|---|
| justify-items | auto | stretch | baseline | [ <item-position> && <overflow-position>? ] | [ legacy && [ left | right | center ] ] | auto | block containers, flex containers, and grid containers | no | n/a | visual | no | specified value
|
|---|
| align-items | auto | stretch | baseline | [ <item-position> && <overflow-position>? ] | auto | block-level elements | no | n/a | visual | no | specified value |
|---|
Issues Index
The exact definition of these properties
outside what’s
what’s defined in Flexbox
is still
being worked out.
This is a
second Working Draft
and is
NOT STABLE.
↵
Or does it have no baseline?
Or is it based on its first column?
↵
Maybe these things are wrong?
CSS 2.1 is really weird about baseline alignment.
This whole section needs to be better defined and reviewed.
↵
Transplant example 10 from flexbox.
↵ Need to dfn a better term for this in Grid.
↵
Should we make
stretch actually work on block-level/abspos replaced boxes?
To maintain legacy compat, this requires adding a new value (named
normal?)
which has the current behavior of stretching non-replaced boxes and start-aligning replaced ones.
↵