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<!doctype html>
<html lang="en">
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<title>CSS Box Alignment Module Level 3</title>
<link href="../default.css" rel="stylesheet" type="text/css">
<link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
<link href="https://www.w3.org/StyleSheets/TR/W3C-WD" rel="stylesheet" type="text/css">
<style type="text/css">
.issue th:first-child { text-align: left !important; }
[rowspan] > img { float: right; }
[rowspan] { vertical-align: middle; }
table small { display: block; }
</style>
</head>
<body class="h-entry">
<div class="head">
<p data-fill-with="logo"><a class="logo" href="http://www.w3.org/">
<img alt="W3C" height="48" src="https://www.w3.org/Icons/w3c_home" width="72">
</a>
</p>
<h1 class="p-name no-ref" id="title">CSS Box Alignment Module Level 3</h1>
<h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">W3C Working Draft,
<time class="dt-updated" datetime="2014-12-18">18 December 2014</time></span></h2>
<div data-fill-with="spec-metadata">
<dl>
<dt>This version:</dt>
<dd><a class="u-url" href="http://www.w3.org/TR/2014/WD-css-align-3-20141218/">http://www.w3.org/TR/2014/WD-css-align-3-20141218/</a></dd>
<dt>Latest version:</dt>
<dd><a href="http://www.w3.org/TR/css-align-3/">http://www.w3.org/TR/css-align-3/</a></dd>
<dt>Editor's Draft:</dt>
<dd><a href="http://dev.w3.org/csswg/css-align/">http://dev.w3.org/csswg/css-align/</a></dd>
<dt>Previous Versions:</dt>
<dd><a href="http://www.w3.org/TR/2013/WD-css3-align-20130514/" rel="previous">http://www.w3.org/TR/2013/WD-css3-align-20130514/</a></dd>
<dd><a href="http://www.w3.org/TR/2012/WD-css3-align-20120612/" rel="previous">http://www.w3.org/TR/2012/WD-css3-align-20120612/</a></dd>
<dt>Feedback:</dt>
<dd><span><a href="mailto:www-style@w3.org?subject=%5Bcss-align%5D%20feedback">www-style@w3.org</a> with subject line “<kbd>[css-align] <var>… message topic …</var></kbd>” (<a href="http://lists.w3.org/Archives/Public/www-style/" rel="discussion">archives</a>)</span></dd>
<dt>Issue Tracking:</dt>
<dd><a href="http://www.w3.org/Style/CSS/Tracker/products/39">Tracker</a></dd>
<dd><a href="#issues-index">Inline In Spec</a></dd>
<dt class="editor">Editors:</dt>
<dd class="editor">
<div class="p-author h-card vcard"><a class="p-name fn u-url url" href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a> (<span class="p-org org">Invited Expert</span>)</div>
</dd>
<dd class="editor">
<div class="p-author h-card vcard"><a class="p-name fn u-url url" href="http://xanthir.com/contact/">Tab Atkins Jr.</a> (<span class="p-org org">Google</span>)</div>
</dd>
</dl>
</div>
<div data-fill-with="warning"></div>
<p class="copyright" data-fill-with="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2014 <a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/copyright-documents">document use</a> rules apply.
</p>
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc no-ref heading settled" id="abstract"><span class="content">Abstract</span></h2>
<div class="p-summary" data-fill-with="abstract">
<p>This module contains the features of <a href="http://www.w3.org/TR/CSS/">CSS</a> 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 <a data-biblio-type="informative" data-link-type="biblio" href="#biblio-css3text" title="CSS3TEXT">[CSS3TEXT]</a> and <a data-biblio-type="informative" data-link-type="biblio" href="#biblio-css3line" title="CSS3LINE">[CSS3LINE]</a>.)</p>
<a href="http://www.w3.org/TR/CSS/">CSS</a> is a language for describing the rendering of structured documents
(such as HTML and XML)
on screen, on paper, in speech, etc.</div>
<h2 class="no-num no-toc no-ref heading settled" id="status"><span class="content">Status of this document</span></h2>
<div data-fill-with="status">
<p><em>This section describes the status of this document at the time of
its publication. Other documents may supersede this document. A list of
current W3C publications and the latest revision of this technical report
can be found in the <a href="http://www.w3.org/TR/">W3C technical reports
index at http://www.w3.org/TR/.</a></em>
</p>
<p>Publication as a Working Draft does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or
obsoleted by other documents at any time. It is inappropriate to cite this
document as other than work in progress.
</p>
<p>The (<a href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a href="mailto:www-style@w3.org">www-style@w3.org</a> (see
<a href="http://www.w3.org/Mail/Request">instructions</a>) is preferred
for discussion of this specification. When sending e-mail, please put the
text “css-align” in the subject, preferably like this:
“[css-align] <em>…summary of comment…</em>”
</p>
<p>This document was produced by the <a href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
the <a href="http://www.w3.org/Style/">Style Activity</a>).
</p>
<p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
2004 W3C Patent Policy</a>. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/32061/status" rel="disclosure">public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
6 of the W3C Patent Policy</a>.</p>
<p>This document is governed by the <a href="http://www.w3.org/2014/Process-20140801/">1 August 2014 W3C Process Document</a>.
</p></div>
<div data-fill-with="at-risk">
<p>The following features are at-risk, and may be dropped during the CR period:
</p>
<ul>
<li><a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-last-baseline">last-baseline</a></li>
</ul></div>
<h2 class="no-num no-toc no-ref heading settled" id="contents"><span class="content">Table of Contents</span></h2>
<div data-fill-with="table-of-contents" role="navigation">
<ul class="toc" role="directory">
<li><a href="#intro"><span class="secno">1</span> <span class="content">
Introduction</span></a>
<ul class="toc">
<li><a href="#placement"><span class="secno">1.1</span> <span class="content">
Module interactions</span></a></li>
<li><a href="#values"><span class="secno">1.2</span> <span class="content">
Values</span></a></li>
</ul>
</li>
<li><a href="#overview"><span class="secno">2</span> <span class="content">
Overview of Alignment Properties</span></a></li>
<li><a href="#alignment-values"><span class="secno">3</span> <span class="content">
Alignment Values</span></a>
<ul class="toc">
<li><a href="#positional-values"><span class="secno">3.1</span> <span class="content">
Positional Alignment: the <span class="css" data-link-type="maybe" title="center">center</span>, <span class="css" data-link-type="maybe" title="start">start</span>, <span class="css" data-link-type="maybe" title="end">end</span>, <span class="css" data-link-type="maybe" title="self-start">self-start</span>, <span class="css" data-link-type="maybe" title="self-end">self-end</span>, <span class="css" data-link-type="maybe" title="flex-start">flex-start</span>, <span class="css" data-link-type="maybe" title="flex-end">flex-end</span>, <span class="css" data-link-type="maybe" title="left">left</span>, and <span class="css" data-link-type="maybe" title="right">right</span> keywords</span></a></li>
<li><a href="#baseline"><span class="secno">3.2</span> <span class="content">
Baseline Alignment: the <span class="css" data-link-type="maybe" title="baseline">baseline</span> and <span class="css" data-link-type="maybe" title="last-baseline">last-baseline</span> keywords</span></a></li>
<li><a href="#distribution-values"><span class="secno">3.3</span> <span class="content">
Distributed Alignment: the <span class="css" data-link-for="" data-link-type="maybe" title="stretch">stretch</span>, <span class="css" data-link-type="maybe" title="space-between">space-between</span>, <span class="css" data-link-type="maybe" title="space-around">space-around</span>, and <span class="css" data-link-type="maybe" title="space-evenly">space-evenly</span> keywords</span></a></li>
<li><a href="#overflow-values"><span class="secno">3.4</span> <span class="content">
Overflow Alignment: the <span class="css" data-link-type="maybe" title="safe">safe</span> and <span class="css" data-link-type="maybe" title="true">true</span> keywords</span></a></li>
</ul>
</li>
<li><a href="#content-distribution"><span class="secno">4</span> <span class="content">
Content Distribution: the <span class="property" data-link-type="propdesc" title="justify-content">justify-content</span> and <span class="property" data-link-type="propdesc" title="align-content">align-content</span> properties</span></a>
<ul class="toc">
<li><a href="#baseline-align-content"><span class="secno">4.1</span> <span class="content">
Baseline Content-Alignment</span></a></li>
<li><a href="#overflow-scroll-position"><span class="secno">4.2</span> <span class="content">
Overflow and Scroll Positions</span></a></li>
</ul>
</li>
<li><a href="#self-alignment"><span class="secno">5</span> <span class="content">
Self-Alignment: Aligning the Box within its Parent</span></a>
<ul class="toc">
<li><a href="#justify-self-property"><span class="secno">5.1</span> <span class="content">
Inline/Main-Axis Alignment: the <span class="property" data-link-type="propdesc" title="justify-self">justify-self</span> property</span></a></li>
<li><a href="#align-self-property"><span class="secno">5.2</span> <span class="content">
Block/Cross-Axis Alignment: the <span class="property" data-link-type="propdesc" title="align-self">align-self</span> property</span></a></li>
<li><a href="#baseline-align-self"><span class="secno">5.3</span> <span class="content">
Baseline Self-Alignment</span></a></li>
</ul>
</li>
<li><a href="#default-alignment"><span class="secno">6</span> <span class="content">
Default Alignment</span></a>
<ul class="toc">
<li><a href="#justify-items-property"><span class="secno">6.1</span> <span class="content">
Inline/Main-Axis Alignment: the <span class="property" data-link-type="propdesc" title="justify-items">justify-items</span> property</span></a></li>
<li><a href="#align-items-property"><span class="secno">6.2</span> <span class="content">
Block/Cross-Axis Alignment: the <span class="property" data-link-type="propdesc" title="align-items">align-items</span> property</span></a></li>
</ul>
</li>
<li><a href="#baseline-rules"><span class="secno">7</span> <span class="content">
Baseline Alignment Details</span></a>
<ul class="toc">
<li><a href="#baseline-export"><span class="secno">7.1</span> <span class="content">
Determining the Baseline of a Box</span></a></li>
<li><a href="#baseline-terms"><span class="secno">7.2</span> <span class="content">
Baseline Alignment Terminology</span></a></li>
<li><a href="#align-by-baseline"><span class="secno">7.3</span> <span class="content">
Aligning Boxes by Baseline</span></a></li>
</ul>
</li>
<li><a href="#changes"><span class="secno">8</span> <span class="content">
Changes</span></a></li>
<li><a href="#acknowledgments"><span class="secno"></span> <span class="content">
Acknowledgments</span></a></li>
<li><a href="#conformance"><span class="secno"></span> <span class="content">
Conformance</span></a>
<ul class="toc">
<li><a href="#conventions"><span class="secno"></span> <span class="content">
Document conventions</span></a></li>
<li><a href="#conformance-classes"><span class="secno"></span> <span class="content">
Conformance classes</span></a></li>
<li><a href="#partial"><span class="secno"></span> <span class="content">
Partial implementations</span></a></li>
<li><a href="#experimental"><span class="secno"></span> <span class="content">
Experimental implementations</span></a></li>
<li><a href="#testing"><span class="secno"></span> <span class="content">
Non-experimental implementations</span></a></li>
</ul>
</li>
<li><a href="#references"><span class="secno"></span> <span class="content">References</span></a>
<ul class="toc">
<li><a href="#normative"><span class="secno"></span> <span class="content">Normative References</span></a></li>
<li><a href="#informative"><span class="secno"></span> <span class="content">Informative References</span></a></li>
</ul>
</li>
<li><a href="#index"><span class="secno"></span> <span class="content">Index</span></a></li>
<li><a href="#property-index"><span class="secno"></span> <span class="content">Property Index</span></a></li>
<li><a href="#issues-index"><span class="secno"></span> <span class="content">Issues Index</span></a></li>
</ul></div>
<main>
<h2 class="heading settled" data-level="1" id="intro"><span class="secno">1. </span><span class="content">
Introduction</span><a class="self-link" href="#intro"></a></h2>
<p><em>This section is not normative.</em></p>
<p>CSS Levels 1 and 2 allowed for the alignment of text via <a class="property" data-link-type="propdesc" href="http://www.w3.org/TR/css-text-3/#text-align">text-align</a> and
the alignment of blocks by balancing <span class="css" data-link-for="margin">auto</span> 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.</p>
<p class="note" role="note">Note: The alignment of text and inline-level content is defined in <a data-biblio-type="informative" data-link-type="biblio" href="#biblio-css3text" title="CSS3TEXT">[CSS3TEXT]</a> and <a data-biblio-type="informative" data-link-type="biblio" href="#biblio-css3line" title="CSS3LINE">[CSS3LINE]</a>.</p>
<p>Inspiration for this document:</p>
<ul>
<li><a href="http://wiki.csswg.org/ideas/centering#alignment-property">summary of a discussion for implementing <CENTER></a>
</li>
<li><a href="https://lists.w3.org/Archives/Member/w3c-css-wg/2008AprJun/0015.html">Minutes from March 2008 F2F</a>
</li>
<li><a href="http://lists.w3.org/Archives/Public/www-style/2012Feb/0743.html">fantasai’s attempt to merge all alignment properties</a>
</li>
</ul>
<h3 class="heading settled" data-level="1.1" id="placement"><span class="secno">1.1. </span><span class="content">
Module interactions</span><a class="self-link" href="#placement"></a></h3>
<p>This module adds some new alignment capabilities to the block layout
model described in <a data-biblio-type="normative" data-link-type="biblio" href="#biblio-css21" title="CSS21">[CSS21]</a> chapters 9 and 10 and defines the interaction
of these properties with the alignment of table cell content using
<a class="property" data-link-type="propdesc" href="http://www.w3.org/TR/CSS21/visudet.html#propdef-vertical-align">vertical-align</a>, as defined in <a data-biblio-type="normative" data-link-type="biblio" href="#biblio-css21" title="CSS21">[CSS21]</a> chapter 17.
The interaction of these properties with
Grid Layout <a data-biblio-type="normative" data-link-type="biblio" href="#biblio-css3-grid-layout" title="CSS3-GRID-LAYOUT">[CSS3-GRID-LAYOUT]</a>
and Flexible Box Layout <a data-biblio-type="normative" data-link-type="biblio" href="#biblio-css3-flexbox" title="CSS3-FLEXBOX">[CSS3-FLEXBOX]</a>
is defined in their respective modules.</p>
<p>No properties in this module apply to the <code>::first-line</code> or
<code>::first-letter</code> pseudo-elements.</p>
<h3 class="heading settled" data-level="1.2" id="values"><span class="secno">1.2. </span><span class="content">
Values</span><a class="self-link" href="#values"></a></h3>
<p>This specification follows the
<a href="http://www.w3.org/TR/CSS21/about.html#property-defs">CSS property
definition conventions</a> from <a data-biblio-type="normative" data-link-type="biblio" href="#biblio-css21" title="CSS21">[CSS21]</a>. Value types not defined in
this specification are defined in CSS Level 2 Revision 1 <a data-biblio-type="normative" data-link-type="biblio" href="#biblio-css21" title="CSS21">[CSS21]</a>.
Other CSS modules may expand the definitions of these value types: for
example <a data-biblio-type="informative" data-link-type="biblio" href="#biblio-css3val" title="CSS3VAL">[CSS3VAL]</a>, when combined with this module, adds the
<a class="css" data-link-type="maybe" href="http://www.w3.org/TR/css-cascade-3/#valuedef-initial">initial</a> keyword as a possible property value.</p>
<p>In addition to the property-specific values listed in their definitions,
all properties defined in this specification also accept the
<a href="http://www.w3.org/TR/CSS21/cascade.html#value-def-inherit">inherit</a>
keyword as their property value. For readability it has not been repeated
explicitly.</p>
<h2 class="heading settled" data-level="2" id="overview"><span class="secno">2. </span><span class="content">
Overview of Alignment Properties</span><a class="self-link" href="#overview"></a></h2>
<p>The <dfn data-dfn-type="dfn" data-noexport="" id="box-alignment-properties">box alignment properties<a class="self-link" href="#box-alignment-properties"></a></dfn> in CSS are a set of 6 properties
that control alignment of boxes within other boxes.
They can be described along two axises:</p>
<ul>
<li>which dimension they apply to (inline vs. stacking), and
</li>
<li>whether they control the position of the box within its parent, or the box’s content within itself.
</li>
</ul>
<p class="note" role="note">Note: This specification 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.</p>
<p>The following table summarizes the <a data-link-type="dfn" href="#box-alignment-properties">box alignment properties</a>
and the display types they can apply to.</p>
<table class="data">
<colgroup span="1"></colgroup>
<colgroup span="2"></colgroup>
<colgroup span="1"></colgroup>
<thead>
<tr>
<th>Common
</th>
<th>Axis
</th>
<th>Aligns
</th>
<th>Applies to
</th>
</tr>
</thead>
<tbody>
<tr>
<th><a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a>
</th>
<td>inline
</td>
<td rowspan="2">
<img alt="" height="106" src="images/content-example.svg" width="106">
content within element
<small>(effectively adjusts padding)</small>
</td>
<td>block containers, <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-container">flex containers</a>, and <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-container">grid containers</a>
</td>
</tr>
<tr>
<th><a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a>
</th>
<td>stacking
</td>
<td>block containers, <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-container">flex containers</a>, and <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-container">grid containers</a>
</td>
</tr>
</tbody>
<tbody>
<tr>
<th><a class="property" data-link-type="propdesc" href="#propdef-justify-self">justify-self</a>
</th>
<td>inline
</td>
<td rowspan="2">
<img alt="" height="106" src="images/self-example.svg" width="106">
element within parent
<small>(effectively adjusts margins)</small>
</td>
<td>block-level elements and <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-item">grid items</a>
</td>
</tr>
<tr>
<th><a class="property" data-link-type="propdesc" href="#propdef-align-self">align-self</a>
</th>
<td>stacking
</td>
<td><a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-item">flex items</a> and <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-item">grid items</a>
</td>
</tr>
</tbody>
<tbody>
<tr>
<th><a class="property" data-link-type="propdesc" href="#propdef-justify-items">justify-items</a>
</th>
<td>inline
</td>
<td rowspan="2">
<img alt="" height="106" src="images/items-example.svg" width="106">
items inside element
<small>(controls child items’ <span class="css" data-link-for="align">justify-self: auto</span>)</small>
</td>
<td><a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-container">grid containers</a>
</td>
</tr>
<tr>
<th><a class="property" data-link-type="propdesc" href="#propdef-align-items">align-items</a>
</th>
<td>stacking
</td>
<td><a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-container">flex containers</a> and <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-container">grid containers</a>
</td>
</tr>
</tbody>
</table>
<p class="note" role="note">Note: The <a class="property" data-link-type="propdesc">*-items</a> values don’t affect the element itself.
When set on a flex container or grid container,
they specify the interpretation of any <span class="css">*-self: auto</span> used on the items in the container element.</p>
<h2 class="heading settled" data-level="3" id="alignment-values"><span class="secno">3. </span><span class="content">
Alignment Values</span><a class="self-link" href="#alignment-values"></a></h2>
<p>All of the alignment properties use a common set of values,
defined below.</p>
<dl>
<dt><dfn data-dfn-type="dfn" data-export="" id="alignment-subject">alignment subject<a class="self-link" href="#alignment-subject"></a></dfn>
</dt>
<dd>
The <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is the thing or things being aligned by the property.
For <a class="property" data-link-type="propdesc" href="#propdef-justify-self">justify-self</a> and <a class="property" data-link-type="propdesc" href="#propdef-align-self">align-self</a>,
the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is the margin box of the box the property is set on.
For <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a> and <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a>,
the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is defined by the layout mode.
</dd>
<dt><dfn data-dfn-type="dfn" data-export="" id="alignment-container">alignment container<a class="self-link" href="#alignment-container"></a></dfn>
</dt>
<dd>
The <a data-link-type="dfn" href="#alignment-container">alignment container</a> is the rectangle that the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is aligned within.
This is defined by the layout mode,
but is usually the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a>’s containing block.
</dd>
</dl>
<h3 class="heading settled" data-level="3.1" id="positional-values"><span class="secno">3.1. </span><span class="content">
Positional Alignment: the <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-center">center</a>, <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>, <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-end">end</a>, <a class="css" data-link-type="maybe" href="#valdef-self-position-self-start">self-start</a>, <a class="css" data-link-type="maybe" href="#valdef-self-position-self-end">self-end</a>, <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-flex-start">flex-start</a>, <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-flex-end">flex-end</a>, <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-left">left</a>, and <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-right">right</a> keywords</span><a class="self-link" href="#positional-values"></a></h3>
<p>The positional alignment keywords specify a position for an <a data-link-type="dfn" href="#alignment-subject">alignment subject</a>
with respect to its <a data-link-type="dfn" href="#alignment-container">alignment container</a>.</p>
<p>The <a class="production css" data-link-type="type" href="#typedef-self-position"><self-position></a> set of values is used by <a class="property" data-link-type="propdesc" href="#propdef-justify-self">justify-self</a> and <a class="property" data-link-type="propdesc" href="#propdef-align-self">align-self</a>
to align the box within its <a data-link-type="dfn" href="#alignment-container">alignment container</a>,
and also by <a class="property" data-link-type="propdesc" href="#propdef-justify-items">justify-items</a> and <a class="property" data-link-type="propdesc" href="#propdef-align-items">align-items</a>
(to specify default values for <a class="property" data-link-type="propdesc" href="#propdef-justify-self">justify-self</a> and <a class="property" data-link-type="propdesc" href="#propdef-align-self">align-self</a>).
The <a class="production css" data-link-type="type" href="#typedef-content-position"><content-position></a> set of values is used by <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a> and <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a>
to align the box’s contents within itself.</p>
<pre class="prod"><dfn data-dfn-type="type" data-export="" id="typedef-self-position"><self-position><a class="self-link" href="#typedef-self-position"></a></dfn> = center <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> start <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> end <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> self-start <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> self-end <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a>
flex-start <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> flex-end <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> left <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> right;
<dfn data-dfn-type="type" data-export="" id="typedef-content-position"><content-position><a class="self-link" href="#typedef-content-position"></a></dfn> = center <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> start <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> end <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> flex-start <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> flex-end <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> left <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> right;
</pre>
<p>Values have the following meanings:</p>
<dl data-dfn-type="value">
<dt><dfn class="css" data-dfn-for="<self-position>, <content-position>" data-dfn-type="value" data-export="" id="valdef-self-position-content-position-center">center<a class="self-link" href="#valdef-self-position-content-position-center"></a></dfn> <small>(self, content)</small>
</dt>
<dd>Centers the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> within its <a data-link-type="dfn" href="#alignment-container">alignment container</a>.
</dd>
<dt><dfn class="css" data-dfn-for="<self-position>, <content-position>" data-dfn-type="value" data-export="" id="valdef-self-position-content-position-start">start<a class="self-link" href="#valdef-self-position-content-position-start"></a></dfn> <small>(self, content)</small>
</dt>
<dd>Aligns the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> to be flush with the <a data-link-type="dfn" href="#alignment-container">alignment container</a>’s start edge.
</dd>
<dt><dfn class="css" data-dfn-for="<self-position>, <content-position>" data-dfn-type="value" data-export="" id="valdef-self-position-content-position-end">end<a class="self-link" href="#valdef-self-position-content-position-end"></a></dfn> <small>(self, content)</small>
</dt>
<dd>Aligns the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> to be flush with the <a data-link-type="dfn" href="#alignment-container">alignment container</a>’s end edge.
</dd>
<dt><dfn class="css" data-dfn-for="<self-position>" data-dfn-type="value" data-export="" id="valdef-self-position-self-start">self-start<a class="self-link" href="#valdef-self-position-self-start"></a></dfn> <small>(self)</small>
</dt>
<dd>Aligns the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> to be flush with the edge of the <a data-link-type="dfn" href="#alignment-container">alignment container</a>
corresponding to the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a>’s start side.
</dd>
<dt><dfn class="css" data-dfn-for="<self-position>" data-dfn-type="value" data-export="" id="valdef-self-position-self-end">self-end<a class="self-link" href="#valdef-self-position-self-end"></a></dfn> <small>(self)</small>
</dt>
<dd>Aligns the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> to be flush with the edge of the <a data-link-type="dfn" href="#alignment-container">alignment container</a>
corresponding to the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a>’s end side.
</dd>
<dt><dfn class="css" data-dfn-for="<self-position>, <content-position>" data-dfn-type="value" data-export="" id="valdef-self-position-content-position-flex-start">flex-start<a class="self-link" href="#valdef-self-position-content-position-flex-start"></a></dfn> <small>(self, content)</small>
</dt>
<dd><strong>Only used in flex layout.</strong> <a data-biblio-type="normative" data-link-type="biblio" href="#biblio-css3-flexbox" title="CSS3-FLEXBOX">[CSS3-FLEXBOX]</a>
Aligns the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> to be flush with the edge of the <a data-link-type="dfn" href="#alignment-container">alignment container</a>
corresponding to the <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-container">flex container</a>’s main-start or cross-start side, as appropriate.
When used in layout modes other than Flexbox,
this value computes to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>.
</dd>
<dt><dfn class="css" data-dfn-for="<self-position>, <content-position>" data-dfn-type="value" data-export="" id="valdef-self-position-content-position-flex-end">flex-end<a class="self-link" href="#valdef-self-position-content-position-flex-end"></a></dfn> <small>(self, content)</small>
</dt>
<dd><strong>Only used in flex layout.</strong>
Aligns the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> to be flush with the edge of the <a data-link-type="dfn" href="#alignment-container">alignment container</a>
corresponding to the <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-container">flex container</a>’s main-end or cross-end side, as appropriate.
When used in layout modes other than Flexbox,
this value computes to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-end">end</a>.
</dd>
<dt><dfn class="css" data-dfn-for="<self-position>, <content-position>" data-dfn-type="value" data-export="" id="valdef-self-position-content-position-left">left<a class="self-link" href="#valdef-self-position-content-position-left"></a></dfn> <small>(self, content)</small>
</dt>
<dd>Aligns the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> to be flush with the <a data-link-type="dfn" href="#alignment-container">alignment container</a>’s <a href="http://www.w3.org/TR/css3-writing-modes/#line-left">line-left</a> edge.
If the property’s axis is not parallel with the inline axis,
this value computes to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>.
</dd>
<dt><dfn class="css" data-dfn-for="<self-position>, <content-position>" data-dfn-type="value" data-export="" id="valdef-self-position-content-position-right">right<a class="self-link" href="#valdef-self-position-content-position-right"></a></dfn> <small>(self, content)</small>
</dt>
<dd>Aligns the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> to be flush with the <a data-link-type="dfn" href="#alignment-container">alignment container</a>’s <a href="http://www.w3.org/TR/css3-writing-modes/#line-right">line-right</a> edge.
If the property’s axis is not parallel with the inline axis,
this value computes to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>.
</dd>
</dl>
<p class="issue" id="issue-511afb43"><a class="self-link" href="#issue-511afb43"></a>
Add example images.
</p>
<h3 class="heading settled" data-level="3.2" id="baseline"><span class="secno">3.2. </span><span class="content">
Baseline Alignment: the <a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-baseline">baseline</a> and <a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-last-baseline">last-baseline</a> keywords</span><a class="self-link" href="#baseline"></a></h3>
<p><dfn data-dfn-type="dfn" data-noexport="" id="baseline-alignment">Baseline alignment<a class="self-link" href="#baseline-alignment"></a></dfn> is a form of positional alignment
that aligns multiple <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> within a <a data-link-type="dfn" href="#shared-alignment-context">shared alignment context</a> (such as cells within a row or column)
by matching up their <a data-link-type="dfn" href="#alignment-baseline">alignment baselines</a>.</p>
<p>The baseline alignment keywords are:</p>
<pre class="prod"><dfn data-dfn-type="type" data-export="" id="typedef-baseline-position"><baseline-position><a class="self-link" href="#typedef-baseline-position"></a></dfn> = baseline <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> last-baseline
</pre>
<p>and are defined below:</p>
<dl data-dfn-for="justify-content, justify-self, justify-items, align-content, align-self, align-items" data-dfn-type="value">
<dt><dfn class="css" data-dfn-for="justify-content, justify-self, justify-items, align-content, align-self, align-items" data-dfn-type="value" data-export="" id="valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-baseline">baseline<a class="self-link" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-baseline"></a></dfn>
</dt>
<dd>
Indicates <dfn data-dfn-type="dfn" data-noexport="" id="first-baseline-alignment">first-baseline alignment<a class="self-link" href="#first-baseline-alignment"></a></dfn>:
aligns one of the box’s <a data-link-type="dfn" href="#first-baselines">first baselines</a>
with the corresponding <a data-link-type="dfn" href="#first-baselines">first baselines</a>
of all the boxes in its <a data-link-type="dfn" href="#baseline-sharing-group">baseline-sharing group</a>.
<p>If the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a>’s position is not fully determined by <a data-link-type="dfn" href="#baseline-alignment">baseline alignment</a>,
the content is <a class="css" data-link-type="maybe" href="#valdef-self-position-self-start">self-start</a>-aligned insofar as possible while preserving the baseline alignment.
(Content that has no <a data-link-type="dfn" href="#first-baselines">first baselines</a> is thus start-aligned.)</p>
</dd>
<dt><dfn class="css" data-dfn-for="justify-content, justify-self, justify-items, align-content, align-self, align-items" data-dfn-type="value" data-export="" id="valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-last-baseline">last-baseline<a class="self-link" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-last-baseline"></a></dfn>
</dt>
<dd>
Indicates <dfn data-dfn-type="dfn" data-noexport="" id="last-baseline-alignment">last-baseline alignment<a class="self-link" href="#last-baseline-alignment"></a></dfn>:
aligns one of the box’s <a data-link-type="dfn" href="#last-baselines">last baselines</a>
with the corresponding <a data-link-type="dfn" href="#last-baselines">last baselines</a>
of all the boxes in its <a data-link-type="dfn" href="#baseline-sharing-group">baseline-sharing group</a>.
<p>If the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a>’s position is not fully determined by <a data-link-type="dfn" href="#baseline-alignment">baseline alignment</a>,
the content is <a class="css" data-link-type="maybe" href="#valdef-self-position-self-end">self-end</a>-aligned insofar as possible while preserving the baseline alignment.
(Content that has no <a data-link-type="dfn" href="#last-baselines">last baselines</a> is thus end-aligned.)</p>
</dd>
</dl>
<p>These values give a box a <dfn data-dfn-type="dfn" data-noexport="" id="baseline-alignment-preference">baseline alignment preference<a class="self-link" href="#baseline-alignment-preference"></a></dfn>:
either "first" or "last", respectively.</p>
<p>When specified for <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a>/<a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a>,
these values trigger <a data-link-type="dfn" href="#baseline-content-alignment">baseline content-alignment</a>,
shifting the content of the box within the box,
and may also affect the sizing of the box itself.
See <a data-section="" href="#baseline-align-content">§4.1
Baseline Content-Alignment</a>.</p>
<p>When specified for <a class="property" data-link-type="propdesc" href="#propdef-align-self">align-self</a>/<a class="property" data-link-type="propdesc" href="#propdef-justify-self">justify-self</a>,
these values trigger <a data-link-type="dfn" href="#baseline-self-alignment">baseline self-alignment</a>,
shifting the entire box within its container,
which may affect the sizing of its container.
See <a data-section="" href="#baseline-align-self">§5.3
Baseline Self-Alignment</a>.</p>
<p>If both <a data-link-type="dfn" href="#baseline-content-alignment">baseline content-alignment</a> <em>and</em> <a data-link-type="dfn" href="#baseline-self-alignment">baseline self-alignment</a> are specified in the same axis on the same box,
only <a data-link-type="dfn" href="#baseline-self-alignment">baseline self-alignment</a> is honored in that axis;
the content-alignment in that axis must be treated as <a class="css" data-link-type="maybe" href="#valdef-self-position-self-start">self-start</a>.</p>
<p class="issue" id="issue-ba851208"><a class="self-link" href="#issue-ba851208"></a>The previous paragraph is fairly arbitrary.
Need some experience to make sure it’s the correct choice out of the two possibilities.</p>
<p class="issue" id="issue-13b9ed6a"><a class="self-link" href="#issue-13b9ed6a"></a>Add example images here.
</p>
<p class="note" role="note">Note: The <a class="property" data-link-type="propdesc" href="http://www.w3.org/TR/CSS21/visudet.html#propdef-vertical-align">vertical-align</a> property will also need a <a class="css" data-link-type="maybe" href="http://www.w3.org/TR/css-line-grid-1/#valdef-box-snap-first-baseline">first-baseline</a> value
because per CSS2.1 for inline blocks, <a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-baseline">baseline</a> is equivalent to <a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-last-baseline">last-baseline</a>.</p>
<h3 class="heading settled" data-level="3.3" id="distribution-values"><span class="secno">3.3. </span><span class="content">
Distributed Alignment: the <a class="css" data-link-for="" data-link-type="maybe" href="#valdef-content-distribution-stretch">stretch</a>, <a class="css" data-link-type="maybe" href="#valdef-content-distribution-space-between">space-between</a>, <a class="css" data-link-type="maybe" href="#valdef-content-distribution-space-around">space-around</a>, and <a class="css" data-link-type="maybe" href="#valdef-content-distribution-space-evenly">space-evenly</a> keywords</span><a class="self-link" href="#distribution-values"></a></h3>
<p>The distribution values are used by <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a> and <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a>
to distribute the <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a>
evenly between the start and end edges of the <a data-link-type="dfn" href="#alignment-container">alignment container</a>.
When the <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> cannot be distributed in this way,
they behave as their <dfn data-dfn-type="dfn" data-export="" id="fallback-alignment">fallback alignment<a class="self-link" href="#fallback-alignment"></a></dfn>.
Each distribution value has an associated <a class="production css" data-link-type="type" href="#typedef-content-position"><content-position></a> as a <a data-link-type="dfn" href="#fallback-alignment">fallback alignment</a>,
but one can alternatively be explicitly specified in the property.</p>
<pre class="prod"><dfn data-dfn-type="type" data-export="" id="typedef-content-distribution"><content-distribution><a class="self-link" href="#typedef-content-distribution"></a></dfn> = space-between <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> space-around <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> space-evenly <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> stretch</pre>
<dl data-dfn-for="<content-distribution>" data-dfn-type="value">
<dt><dfn class="css" data-dfn-for="<content-distribution>" data-dfn-type="value" data-export="" id="valdef-content-distribution-space-between">space-between<a class="self-link" href="#valdef-content-distribution-space-between"></a></dfn>
</dt>
<dd>
The <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> are evenly distributed in the <a data-link-type="dfn" href="#alignment-container">alignment container</a>.
The first <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is placed flush with the start edge of the <a data-link-type="dfn" href="#alignment-container">alignment container</a>,
the last <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is placed flush with the end edge of the <a data-link-type="dfn" href="#alignment-container">alignment container</a>,
and the remaining <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> are distributed so that the spacing between any two adjacent <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> is the same.
Unless otherwise specified,
this value falls back to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>.
</dd>
<dt><dfn class="css" data-dfn-for="<content-distribution>" data-dfn-type="value" data-export="" id="valdef-content-distribution-space-around">space-around<a class="self-link" href="#valdef-content-distribution-space-around"></a></dfn>
</dt>
<dd>
The <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> are evenly distributed in the <a data-link-type="dfn" href="#alignment-container">alignment container</a>,
with a half-size space on either end.
The <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> are distributed so that the spacing between any two adjacent <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> is the same,
and the spacing before the first and after the last <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is half the size of the other spacing.
Unless otherwise specified,
this value falls back to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-center">center</a>.
</dd>
<dt><dfn class="css" data-dfn-for="<content-distribution>" data-dfn-type="value" data-export="" id="valdef-content-distribution-space-evenly">space-evenly<a class="self-link" href="#valdef-content-distribution-space-evenly"></a></dfn>
</dt>
<dd>
The <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> are evenly distributed in the <a data-link-type="dfn" href="#alignment-container">alignment container</a>,
with a full-size space on either end.
The <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> are distributed so that the spacing between any two adjacent <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a>,
before the first <a data-link-type="dfn" href="#alignment-subject">alignment subject</a>,
and after the last <a data-link-type="dfn" href="#alignment-subject">alignment subject</a>
is the same.
Unless otherwise specified,
this value falls back to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-center">center</a>.
</dd>
<dt><dfn class="css" data-dfn-for="<content-distribution>" data-dfn-type="value" data-export="" id="valdef-content-distribution-stretch">stretch<a class="self-link" href="#valdef-content-distribution-stretch"></a></dfn>
</dt>
<dd>
If the combined size of the <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> is less than the size of the <a data-link-type="dfn" href="#alignment-container">alignment container</a>,
any <span class="css" data-link-for="width">auto</span>-sized <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> have their size increased equally (not proportionally),
while still respecting the constraints imposed by <a class="property" data-link-type="propdesc" href="http://www.w3.org/TR/CSS21/visudet.html#propdef-max-height">max-height</a>/<a class="property" data-link-type="propdesc" href="http://www.w3.org/TR/CSS21/visudet.html#propdef-max-width">max-width</a>,
so that the combined size exactly fills the <a data-link-type="dfn" href="#alignment-container">alignment container</a>.
<p>Unless otherwise specified,
this value falls back to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-flex-start">flex-start</a>.
<span class="note" role="note">(For layout modes other than flex layout, <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-flex-start">flex-start</a> is identical to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>.)</span></p>
<p class="issue" id="issue-3ea08feb"><a class="self-link" href="#issue-3ea08feb"></a>Should this value allow a fallback alignment on <a class="property" data-link-type="propdesc" href="#propdef-align-self">align-self</a> and <a class="property" data-link-type="propdesc" href="#propdef-justify-self">justify-self</a>,
like it does on <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a> and <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a>?</p>
</dd>
</dl>
<p class="issue" id="issue-77ee454e"><a class="self-link" href="#issue-77ee454e"></a>
Add even more example images.
</p>
<h3 class="heading settled" data-level="3.4" id="overflow-values"><span class="secno">3.4. </span><span class="content">
Overflow Alignment: the <a class="css" data-link-type="maybe" href="#valdef-overflow-position-safe">safe</a> and <a class="css" data-link-type="maybe" href="#valdef-overflow-position-true">true</a> keywords</span><a class="self-link" href="#overflow-values"></a></h3>
<p>When the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is larger than the <a data-link-type="dfn" href="#alignment-container">alignment container</a>,
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.</p>
<p>To help combat this problem,
an <dfn data-dfn-type="dfn" data-export="" id="overflow-alignment">overflow alignment<a class="self-link" href="#overflow-alignment"></a></dfn> 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.</p>
<p>If the <a data-link-type="dfn" href="#overflow-alignment">overflow alignment</a> isn’t explicitly specified,
the default <a data-link-type="dfn" href="#overflow-alignment">overflow alignment</a> is determined by the layout mode.
Document-centric layout modes, such as block layout, default to "safe" <a data-link-type="dfn" href="#overflow-alignment">overflow alignment</a>,
while design-centric layout modes, such as flex layout, default to "true" <a data-link-type="dfn" href="#overflow-alignment">overflow alignment</a>.</p>
<pre class="prod"><dfn data-dfn-type="type" data-export="" id="typedef-overflow-position"><overflow-position><a class="self-link" href="#typedef-overflow-position"></a></dfn> = true <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> safe</pre>
<dl data-dfn-for="<overflow-position>" data-dfn-type="value">
<dt><dfn class="css" data-dfn-for="<overflow-position>" data-dfn-type="value" data-export="" id="valdef-overflow-position-safe">safe<a class="self-link" href="#valdef-overflow-position-safe"></a></dfn>
</dt>
<dd>
If the size of the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> overflows the <a data-link-type="dfn" href="#alignment-container">alignment container</a>,
the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is instead aligned as if the alignment mode were <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>.
</dd>
<dt><dfn class="css" data-dfn-for="<overflow-position>" data-dfn-type="value" data-export="" id="valdef-overflow-position-true">true<a class="self-link" href="#valdef-overflow-position-true"></a></dfn>
</dt>
<dd>
Regardless of the relative sizes of the <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> and <a data-link-type="dfn" href="#alignment-container">alignment container</a>,
the given alignment value is honored.
</dd>
</dl>
<p class="issue" id="issue-8fcc582f"><a class="self-link" href="#issue-8fcc582f"></a>
Transplant example 10 from flexbox.
</p>
<h2 class="heading settled" data-level="4" id="content-distribution"><span class="secno">4. </span><span class="content">
Content Distribution: the <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a> and <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a> properties</span><a class="self-link" href="#content-distribution"></a></h2>
<p>The <dfn data-dfn-type="dfn" data-export="" id="content-distribution-properties">content distribution properties<a class="self-link" href="#content-distribution-properties"></a></dfn> <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a> and <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a>
control alignment of the box’s content within the box.</p>
<div class="figure">
<img alt="Diagram showing that the alignment of the content within the element is affected." height="212" src="images/content-example.svg" width="212">
</div>
<table class="definition propdef">
<tbody>
<tr>
<th>Name:</th>
<td><dfn class="css" data-dfn-type="property" data-export="" id="propdef-justify-content">justify-content<a class="self-link" href="#propdef-justify-content"></a></dfn>, <dfn class="css" data-dfn-type="property" data-export="" id="propdef-align-content">align-content<a class="self-link" href="#propdef-align-content"></a></dfn></td>
</tr>
<tr>
<th>Value:</th>
<td class="prod">auto <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> <a class="production css" data-link-type="type" href="#typedef-baseline-position"><baseline-position></a> <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-one">|</a> <a class="production css" data-link-type="type" href="#typedef-content-distribution"><content-distribution></a> <a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#comb-any">||</a> [ <a class="production css" data-link-type="type" href="#typedef-overflow-position"><overflow-position></a><a data-link-for="" data-link-type="grammar" href="http://dev.w3.org/csswg/css-values-3/#mult-opt">?</a> && <a class="production css" data-link-type="type" href="#typedef-content-position"><content-position></a> ]</td>
</tr>
<tr>
<th>Initial:</th>
<td>auto</td>
</tr>
<tr>
<th>Applies to:</th>
<td>block containers, flex containers, and grid containers</td>
</tr>
<tr>
<th>Inherited:</th>
<td>no</td>
</tr>
<tr>
<th>Percentages:</th>
<td>n/a</td>
</tr>
<tr>
<th>Media:</th>
<td>visual</td>
</tr>
<tr>
<th>Computed value:</th>
<td>specified value, except for <span class="css" data-link-for="justify-content">auto</span> (see prose)</td>
</tr>
<tr>
<th>Animatable:</th>
<td>no</td>
</tr>
</tbody></table>
<p>Aligns the contents of the box as a whole along the box’s inline/row/main axis.
Values other than <dfn class="css" data-dfn-for="justify-content, align-content" data-dfn-type="value" data-export="" id="valdef-justify-content-align-content-auto">auto<a class="self-link" href="#valdef-justify-content-align-content-auto"></a></dfn> are defined in <a data-section="" href="#alignment-values">§3
Alignment Values</a>, above.
If both a <a class="production css" data-link-type="type" href="#typedef-content-distribution"><content-distribution></a> and <a class="production css" data-link-type="type" href="#typedef-content-position"><content-position></a> are given,
the <a class="production css" data-link-type="type" href="#typedef-content-position"><content-position></a> provides an explicit <a data-link-type="dfn" href="#fallback-alignment">fallback alignment</a>.</p>
<hr>
<dl>
<dt>Block Containers:
</dt>
<dd>
The <a data-link-type="dfn" href="#alignment-container">alignment container</a> is the <a data-link-type="dfn" href="http://dev.w3.org/csswg/css-display-3/#block-container">block container</a>’s content box.
The <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is the entire contents of the block, as a unit.
<p>The <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a> property applies along the <a data-link-type="dfn" href="http://www.w3.org/TR/css-writing-modes-3/#block-axis-">block axis</a>,
but if a <a class="production css" data-link-type="type" href="#typedef-content-distribution"><content-distribution></a> is specified
the <a data-link-type="dfn" href="#fallback-alignment">fallback alignment</a> is used instead.
The <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a> property does not apply to and has no effect on block containers.</p>
<p>All values other than <span class="css" data-link-for="justify-content">auto</span> force the block container to establish a new formatting context.
For table cells, the behavior of the <span class="css" data-link-for="justify-content">auto</span> depends on the computed value of <a class="property" data-link-type="propdesc" href="http://www.w3.org/TR/CSS21/visudet.html#propdef-vertical-align">vertical-align</a>:
<span class="css" data-link-for="vertical-align">top</span> makes it behave as <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>,
<span class="css" data-link-for="vertical-align">middle</span> makes it behave as <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-center">center</a>,
<span class="css" data-link-for="vertical-align">bottom</span> makes it behave as <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-end">end</a>,
and all other values make it behave as <a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-baseline">baseline</a>.
<span class="css" data-link-for="justify-content">auto</span> otherwise behaves as <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>.</p>
</dd>
<dt>Multicol Layout:
</dt>
<dd>
The <a data-link-type="dfn" href="#alignment-container">alignment container</a> is the <a data-link-type="dfn" href="http://www.w3.org/TR/css3-multicol/#multi-column-element">multi-column element</a>’s content box.
The <a data-link-type="dfn" href="#alignment-subject">alignment subject</a> is the column boxes, as a unit.
<p>The <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a> property applies along the <a data-link-type="dfn" href="http://www.w3.org/TR/css-writing-modes-3/#block-axis-">block axis</a>,
but if a <a class="production css" data-link-type="type" href="#typedef-content-distribution"><content-distribution></a> is specified
the <a data-link-type="dfn" href="#fallback-alignment">fallback alignment</a> is used instead.
The <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a> property does not apply to and has no effect on multi-column elements.</p>
<p><span class="css" data-link-for="justify-content">auto</span> behaves as <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>.</p>
</dd>
<dt>Flex Containers:
</dt>
<dd>
<span class="css" data-link-for="justify-content">auto</span> computes to <a class="css" data-link-for="" data-link-type="maybe" href="#valdef-content-distribution-stretch">stretch</a>.
<p>The <a data-link-type="dfn" href="#alignment-container">alignment container</a> is the <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-container">flex container</a>’s content box.
For <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a>, the <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> are the <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-item">flex items</a> in each <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-line">flex line</a>;
for <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a>, the <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> are the <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-line">flex lines</a>.</p>
<p>The <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a> property applies along the <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#cross-axis">cross axis</a>.
The <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a> property applies along the <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#main-axis">main axis</a>,
but since flexing in the <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#main-axis">main axis</a> is controlled by <a class="property" data-link-type="propdesc" href="http://www.w3.org/TR/css-flexbox-1/#propdef-flex">flex</a>,
<a class="css" data-link-for="" data-link-type="maybe" href="#valdef-content-distribution-stretch">stretch</a> behaves as <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-flex-start">flex-start</a>.</p>
<p>See <a data-biblio-type="normative" data-link-type="biblio" href="#biblio-css3-flexbox" title="CSS3-FLEXBOX">[CSS3-FLEXBOX]</a> for details.</p>
</dd>
<dt>Grid Containers:
</dt>
<dd>
<span class="css" data-link-for="justify-content">auto</span> computes to <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a>.
<p>The <a data-link-type="dfn" href="#alignment-container">alignment container</a> is the <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-container">grid container</a>’s content box.
The <a data-link-type="dfn" href="#alignment-subject">alignment subjects</a> are the <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-track">grid tracks</a>.</p>
<p>The <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a> property applies along the <a data-link-type="dfn" href="http://www.w3.org/TR/css-writing-modes-3/#block-axis-" title="block axis">block (column) axis</a>,
aligning the <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-row-">grid rows</a>.
The <a class="property" data-link-type="propdesc" href="#propdef-justify-content">justify-content</a> property applies along the <a data-link-type="dfn" href="http://www.w3.org/TR/css-writing-modes-3/#inline-axis-" title="inline axis">inline (row) axis</a>,
aligning the <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-column-">grid columns</a>.</p>
<p>See <a data-biblio-type="normative" data-link-type="biblio" href="#biblio-css3-grid-layout" title="CSS3-GRID-LAYOUT">[CSS3-GRID-LAYOUT]</a> for details.</p>
</dd>
</dl>
<h3 class="heading settled" data-level="4.1" id="baseline-align-content"><span class="secno">4.1. </span><span class="content">
Baseline Content-Alignment</span><a class="self-link" href="#baseline-align-content"></a></h3>
<p>The content of boxes participating in row-like layout contexts (<a data-link-type="dfn" href="#shared-alignment-context">shared alignment contexts</a>)
can be baseline-aligned to each other.
This effectively increases the padding on the box
to align the <a data-link-type="dfn" href="#alignment-baseline">alignment baseline</a> of its contents
with that of other baseline-aligned boxes in its <a data-link-type="dfn" href="#baseline-sharing-group" title="baseline-sharing group">group</a>.</p>
<p>The set of boxes that participate in <dfn data-dfn-type="dfn" data-export="" id="baseline-content-alignment" title="baseline content-alignment|first-baseline content-alignment|last-baseline content-alignment">baseline content-alignment<a class="self-link" href="#baseline-content-alignment"></a></dfn>
depends on the layout model:</p>
<dl>
<dt>Table Cells:
</dt>
<dd>
A <a data-link-type="dfn">table cell</a> participates in first (last) <a data-link-type="dfn" href="#baseline-content-alignment">baseline content-alignment</a>
in either its row or column (whichever matches its <a data-link-type="dfn" href="http://www.w3.org/TR/css-writing-modes-3/#inline-axis-">inline axis</a>)
if its computed <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a> is <a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-baseline">baseline</a> (<a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-last-baseline">last-baseline</a>).
</dd>
<dt>Flex Items:
</dt>
<dd>
A <a data-link-type="dfn" href="http://www.w3.org/TR/css-flexbox-1/#flex-item">flex item</a> participates in first (last) <a data-link-type="dfn" href="#baseline-content-alignment">baseline content-alignment</a>
in its flex line if
its computed <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a> is <a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-baseline">baseline</a> (<a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-last-baseline">last-baseline</a>)
and its computed <a class="property" data-link-type="propdesc" href="#propdef-align-self">align-self</a> is <a class="css" data-link-for="align-self" data-link-type="maybe" href="http://www.w3.org/TR/css-flexbox-1/#valdef-align-items-align-self-stretch">stretch</a> or <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a> (<a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-end">end</a>).
</dd>
<dt>Grid Items:
</dt>
<dd>
A <a data-link-type="dfn" href="http://www.w3.org/TR/css-grid-1/#grid-item">grid item</a> participates in first (last) <a data-link-type="dfn" href="#baseline-content-alignment">baseline content-alignment</a>
in either its row or column (whichever matches its <a data-link-type="dfn" href="http://www.w3.org/TR/css-writing-modes-3/#inline-axis-">inline axis</a>)
if its computed <a class="property" data-link-type="propdesc" href="#propdef-align-content">align-content</a> is <a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-baseline">baseline</a> (<a class="css" data-link-type="maybe" href="#valdef-justify-content-justify-self-justify-items-align-content-align-self-align-items-last-baseline">last-baseline</a>),
and its computed <a class="property" data-link-type="propdesc" href="#propdef-align-self">align-self</a> or <a class="property" data-link-type="propdesc" href="#propdef-justify-self">justify-self</a> (whichever affects its <a data-link-type="dfn" href="http://www.w3.org/TR/css-writing-modes-3/#block-axis-">block axis</a>) is <span class="css" data-link-for="justify-self">stretch</span> or <a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-start">start</a> (<a class="css" data-link-type="maybe" href="#valdef-self-position-content-position-end">end</a>).
</dd>
</dl>