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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html lang=en>
<head profile="http://dublincore.org/documents/2008/08/04/dc-html/ ">
<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
<title>CSS Grid Layout</title>
<link href="http://purl.org/dc/terms/" rel=schema.dcterms>
<link href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=dcterms.rights>
<meta content="CSS Grid Layout" name=dcterms.title>
<meta content=text name=dcterms.type>
<meta content=2013-05-02 name=dcterms.date>
<meta content="Tab Atkins Jr." name=dcterms.creator>
<meta content="Elika J. Etemad" name=dcterms.creator>
<meta content="Rossen Atanassov" name=dcterms.creator>
<meta content=W3C name=dcterms.publisher>
<meta content="http://dev.w3.org/csswg/css3-grid-layout/"
name=dcterms.identifier>
<link href="../default.css" rel=stylesheet type="text/css">
<link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
type="text/css">
<style type="text/css">
.example {
clear:both
}
th {
text-align:left
}
.pseudo-code {
font-family:monospace
}
.pseudo-code > ol {
list-style-type:decimal
}
.pseudo-code > ol > li > ol {
list-style-type:lower-latin
}
.pseudo-code > ol > li > ol > li > ol {
list-style-type:lower-roman
}
.pseudo-code ul {
list-style-type:disc
}
dd > p:nth-child(1) {
margin-top:0
}
</style>
<body>
<div class=head> <!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1 class=title id=title>CSS Grid Layout</h1>
<h2 class="no-num no-toc" id=longstatus-date>Editor's Draft, 2 May 2013</h2>
<dl>
<dt>This version:
<!-- <dd><a href="http://dev.w3.org/csswg/css3-grid-layout/">http://www.w3.org/TR/2013/WD-css3-grid-layout-20130502/</a> -->
<dd><a
href="http://dev.w3.org/csswg/css3-grid-layout/">http://dev.w3.org/csswg/css3-grid-layout/</a>
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css3-grid-layout/">http://www.w3.org/TR/css3-grid-layout/</a>
<dt>Editor's draft:
<dd><a
href="http://dev.w3.org/csswg/css3-grid-layout/">http://dev.w3.org/csswg/css3-grid-layout/</a>
<dt>Previous version
<dd><a
href="http://www.w3.org/TR/2012/WD-css3-grid-layout-20121106/">http://www.w3.org/TR/2012/WD-css3-grid-layout-20121106/</a>
<dt>Issues List:
<dd><a
href="https://www.w3.org/Bugs/Public/buglist.cgi?product=CSS&component=Grid+Layout&bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED">In
Bugzilla</a>
<dt>Feedback:
<dd><a
href="mailto:www-style@w3.org?subject=%5Bcss3-grid-layout%5D%20feedback">www-style@w3.org</a>
with subject line “<kbd>[css3-grid-layout] <var>… message topic
…</var></kbd>” (<a
href="http://lists.w3.org/Archives/Public/www-style/"
rel=discussion>archives</a>)
<dt>Editors:
<dd class=hcard><a class="fn url"
href="http://www.xanthir.com/contact">Tab Atkins Jr.</a>, <span
class=org>Google Inc.</span>
<dd class=hcard><a class="fn url"
href="http://fantasai.inkedblade.net/contact">Elika J. Etemad</a>, <span
class=org>Mozilla</span>
<dd class=hcard><a href="mailto:ratan@microsoft.com">Rossen
Atanassov</a>, <span class=org>Microsoft Corporation</span>
<dt>Authors and former editors:
<dd><a href="mailto:alexmog@microsoft.com">Alex Mogilevsky</a>, Microsoft
Corporation
<dd><a href="mailto:pcupp@microsoft.com">Phil Cupp</a>, Microsoft
Corporation
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2013 <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>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id=abstract>Abstract</h2>
<p> This CSS module defines a two-dimensional grid-based layout system,
optimized for user interface design. In the grid layout model, the
children of a grid container can be positioned into arbitrary slots in a
flexible or fixed predefined layout grid.
<h2 class="no-num no-toc" id=status>Status of this document</h2>
<!--begin-status-->
<p>This is a public copy of the editors' draft. It is provided for
discussion only and may change at any moment. Its publication here does
not imply endorsement of its contents by W3C. Don't cite this document
other than as work in progress.
<p>The (<a
href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
mailing list <a
href="mailto:www-style@w3.org?Subject=%5Bcss3-grid-layout%5D%20PUT%20SUBJECT%20HERE">
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
“css3-grid-layout” in the subject, preferably like this:
“[<!---->css3-grid-layout<!---->] <em>…summary of comment…</em>”
<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>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>
<!--end-status-->
<p>The following features are at risk: …
<h2 class="no-num no-toc" id=contents> Table of contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#intro"><span class=secno>1. </span> Introduction and
Overview</a>
<ul class=toc>
<li><a href="#background"><span class=secno>1.1. </span> Background and
Motivation</a>
<li><a href="#adapting-to-available-space"><span class=secno>1.2.
</span> Adapting Layouts to Available Space</a>
<li><a href="#source-independence"><span class=secno>1.3. </span> Source
Independence</a>
<li><a href="#grid-layering"><span class=secno>1.4. </span> Grid
Layering of Elements</a>
</ul>
<li><a href="#grid-concepts"><span class=secno>2. </span> Grid Layout
Concepts and Terminology</a>
<ul class=toc>
<li><a href="#grid-track-concept"><span class=secno>2.1. </span> Grid
Tracks</a>
<li><a href="#grid-line-concept"><span class=secno>2.2. </span> Grid
Lines</a>
<li><a href="#grid-area-concept"><span class=secno>2.3. </span> Grid
Areas</a>
</ul>
<li><a href="#grid-model"><span class=secno>3. </span> Grid Layout Box
Model</a>
<ul class=toc>
<li><a href="#grid-containers"><span class=secno>3.1. </span> Grid
Containers: the ‘<code class=css>grid</code>’ and ‘<code
class=css>inline-grid</code>’ ‘<code
class=property>display</code>’ values</a>
<li><a href="#subgrids-the-subgrid-display-value"><span class=secno>3.2.
</span>Subgrids: the ‘<code class=css>subgrid</code>’ ‘<code
class=property>display</code>’ value</a>
</ul>
<li><a href="#grid-items"><span class=secno>4. </span> Grid Items</a>
<ul class=toc>
<li><a href="#position-grid"><span class=secno>4.1. </span> Non-children
Grid Items</a>
<li><a href="#abspos-items"><span class=secno>4.2. </span>
Absolutely-positioned Grid Children</a>
<li><a href="#visibility-collapse"><span class=secno>4.3. </span>
Collapsed Grid Items: the ‘<code class=property>visibility</code>’
property</a>
<li><a href="#order-property"><span class=secno>4.4. </span> Reordered
Grid Items: the ‘<code class=property>order</code>’ property</a>
</ul>
<li><a href="#grid-definition"><span class=secno>5. </span> Defining the
Grid</a>
<ul class=toc>
<li><a href="#track-sizing"><span class=secno>5.1. </span> Track Sizing:
the ‘<code class=property>grid-definition-rows</code>’ and ‘<code
class=property>grid-definition-columns</code>’ properties</a>
<ul class=toc>
<li><a href="#named-lines"><span class=secno>5.1.1. </span> Named Grid
Lines</a>
<li><a href="#repeat-notation"><span class=secno>5.1.2. </span>
Repeating Rows and Columns: the ‘<code class=css>repeat()</code>’
notation</a>
<li><a href="#fr-unit"><span class=secno>5.1.3. </span> Flexible
Lengths: the ‘<code class=css>fr</code>’ unit</a>
<li><a href="#resolved-track-list"><span class=secno>5.1.4. </span>
Resolved Values</a>
</ul>
<li><a href="#grid-template-property"><span class=secno>5.2. </span>
Named Areas: the ‘<code class=property>grid-template</code>’
property</a>
<li><a href="#auto-tracks"><span class=secno>5.3. </span> Auto-generated
Rows and Columns: the ‘<code class=property>grid-auto-rows</code>’
and ‘<code class=property>grid-auto-columns</code>’ properties</a>
</ul>
<li><a href="#placement"><span class=secno>6. </span> Placing Grid
Items</a>
<ul class=toc>
<li><a href="#line-placement"><span class=secno>6.1. </span> Line-based
Placement: the ‘<code class=property>grid-before</code>’, ‘<code
class=property>grid-start</code>’, ‘<code
class=property>grid-after</code>’, and ‘<code
class=property>grid-end</code>’ properties</a>
<li><a href="#placement-shorthands"><span class=secno>6.2. </span>
Placement Shorthands: the ‘<code
class=property>grid-column</code>’, ‘<code
class=property>grid-row</code>’, and ‘<code
class=property>grid-area</code>’ properties</a>
<li><a href="#grid-auto-flow-property"><span class=secno>6.3. </span>
Automatic Placement: the ‘<code
class=property>grid-auto-flow</code>’ property</a>
<ul class=toc>
<li><a href="#auto-placement-algo"><span class=secno>6.3.1. </span>
Automatic Grid Item Placement Algorithm</a>
</ul>
</ul>
<li><a href="#alignment"><span class=secno>7. </span> Alignment</a>
<ul class=toc>
<li><a href="#auto-margins"><span class=secno>7.1. </span> Aligning with
‘<code class=css>auto</code>’ margins</a>
<li><a href="#row-align"><span class=secno>7.2. </span> Row-axis
Alignment: the ‘<code class=property>justify-self</code>’ and
‘<code class=property>justify-items</code>’ properties</a>
<li><a href="#column-align"><span class=secno>7.3. </span> Column-axis
Alignment: the ‘<code class=property>align-self</code>’ and
‘<code class=property>align-items</code>’ properties</a>
<li><a href="#z-order"><span class=secno>7.4. </span> Z-axis Ordering:
the ‘<code class=property>z-index</code>’ property</a>
<li><a href="#grid-baselines"><span class=secno>7.5. </span> Grid
Baselines</a>
</ul>
<li><a href="#layout-algorithm"><span class=secno>8. </span> Grid Layout
Algorithm</a>
<ul class=toc>
<li><a href="#algo-terms"><span class=secno>8.1. </span> Definition of
Terms for use in Calculating Grid Track Sizes</a>
<li><a href="#grid-track-sizing-algorithm"><span class=secno>8.2.
</span> Grid Track Sizing Algorithm</a>
<li><a href="#shrink-to-fit"><span class=secno>8.3. </span> Defining the
Shrink-to-fit Behavior of Grid Elements</a>
</ul>
<li><a href="#pagination"><span class=secno>9. </span> Fragmenting Grid
Layout</a>
<li><a href="#conformance"><span class=secno>10. </span> Conformance</a>
<ul class=toc>
<li><a href="#interactions"><span class=secno>10.1. </span> Module
interactions</a>
<li><a href="#values"><span class=secno>10.2. </span> Values</a>
<li><a href="#conventions"><span class=secno>10.3. </span> Document
conventions</a>
<li><a href="#conformance-classes"><span class=secno>10.4. </span>
Conformance classes</a>
<li><a href="#partial"><span class=secno>10.5. </span> Partial
implementations</a>
<li><a href="#experimental"><span class=secno>10.6. </span> Experimental
implementations</a>
<li><a href="#testing"><span class=secno>10.7. </span> Non-experimental
implementations</a>
</ul>
<li class=no-num><a href="#acknowledgements"> Acknowledgements</a>
<li class=no-num><a href="#references"> References</a>
<ul class=toc>
<li class=no-num><a href="#normative-references"> Normative
references</a>
<li class=no-num><a href="#other-references"> Other references</a>
</ul>
<li class=no-num><a href="#index"> Index</a>
<li class=no-num><a href="#property-index"> Property index</a>
</ul>
<!--end-toc-->
<h2 id=intro><span class=secno>1. </span> Introduction and Overview</h2>
<p> Grid layout contains features targeted at web application authors. The
grid can be used to achieve many different layouts. It excels at dividing
up space for major regions of an application, or defining the relationship
in terms of size, position, and layer between parts of a control built
from HTML primitives.
<p> Like tables, grid layout enables an author to align elements into
columns and rows, but unlike tables, grid layout doesn't have content
structure, and thus enables a wide variety of layouts not possible with
tables. For example, the children of a grid container can position
themselves such that they overlap and layer similar to positioned
elements.
<p> In addition, the absence of content structure in grid layout helps to
manage changes to layout by using fluid and source order independent
layout techniques. By combining media queries with the CSS properties that
control layout of the grid container and its children, authors can adapt
their layout to changes in device form factors, orientation, and available
space, without needing to alter the semantic nature of their content.
<p class=issue> A common use of design grids is to allow content to flow
normally, but "snap" components to grid lines based on their normal flow
position. Consider adding a grid placement algorithm based on such
relative positioning. Note that this is a non-trivial issue as it impacts
the static flow of content. In addition, the grid's algorithm currently
depends on knowing the position of every grid item in advance to determine
the size of its tracks; when snapping to grid lines, however, the line to
which the grid item will snap is influenced by both the item's size and
the size of tracks the item covers.
<h3 id=background><span class=secno>1.1. </span> Background and Motivation</h3>
<div class=sidefigure> <img
alt="Image: Application layout example requiring horizontal and vertical alignment."
class=figure src="images/basic-form.png">
<p class=caption>Application layout example requiring horizontal and
vertical alignment.
</div>
<p> As websites evolved from simple documents into complex, interactive
applications, tools for document layout, e.g. floats, were not necessarily
well suited for application layout. By using a combination of tables,
JavaScript, or careful measurements on floated elements, authors
discovered workarounds to achieve desired layouts. Layouts that adapted to
the available space were often brittle and resulted in counter-intuitive
behavior as space became constrained. As an alternative, authors of many
web applications opted for a fixed layout that cannot take advantage of
changes in the available rendering space on a screen.
<p> The capabilities of grid layout address these problems. It provides a
mechanism for authors to divide available space for layout into columns
and rows using a set of predictable sizing behaviors. Authors can then
precisely position and size the building block elements of their
application by into <a href="#grid-area"><i>grid areas</i></a> defined by
these columns and rows. Figure 1 illustrates a basic layout which can be
achieved with grid layout.
<h3 id=adapting-to-available-space><span class=secno>1.2. </span> Adapting
Layouts to Available Space</h3>
<div class=sidefigure>
<p> <img
alt="Image: Five grid items arranged according to content size and available space."
src="images/game-smaller.png">
<p class=caption> Five grid items arranged according to content size and
available space.
</div>
<div class=sidefigure>
<p> <img
alt="Image: Growth in the grid due to an increase in available space."
src="images/game-larger.png">
<p class=caption> Growth in the grid due to an increase in available
space.
</div>
<p> Grid layout can be used to intelligently reflow elements within a
webpage. Figure 2 represents a game with five major areas in the layout:
the game title, stats area, game board, score area, and control area. The
author's intent is to divide the space for the game such that:
<ul>
<li> The stats area always appears immediately under the game title.
<li> The game board appears to the right of the stats and title.
<li> The top of the game title and the game board should always align.
<li> The bottom of the game board and the stats area align when the game
has reached its minimum height, but otherwise the game board will stretch
to take advantage of all the screen real-estate available to it.
<li> The score area should align into the column created by the game and
stats area, while the controls are centered under the board.
</ul>
<p> As an alternative to using script to control the absolute position,
width, and height of all elements, the author can use grid layout, as
shown in Figure 3. The following example shows how an author might achieve
all the sizing, placement, and alignment rules declaratively.
<p> Note that there are multiple ways to specify the structure of the grid
and to position and size <a href="#grid-item"><i>grid items</i></a>, each
optimized for different scenarios. This example illustrates one that an
author may use to define the position and space for each <a
href="#grid-item"><i>grid item</i></a> using the ‘<a
href="#grid-definition-rows"><code
class=property>grid-definition-rows</code></a>’ and ‘<a
href="#grid-definition-columns"><code
class=property>grid-definition-columns</code></a>’ properties on the <a
href="#grid-container"><i>grid container</i></a>, and the ‘<a
href="#grid-row"><code class=property>grid-row</code></a>’ and ‘<a
href="#grid-column"><code class=property>grid-column</code></a>’
properties on each <a href="#grid-item"><i>grid item</i></a>.
<pre class=example>
<style type="text/css">
#grid {
display: grid;
/* Two columns: the first sized to content, the second receives
* the remaining space, but is never smaller than the minimum
* size of the board or the game controls, which occupy this
* column. */
grid-definition-columns: auto minmax(min-content, 1fr);
/* Three rows: the first and last sized to content, the middle
* row receives the remaining space, but is never smaller than
* the minimum height of the board or stats areas. */
grid-definition-rows: auto minmax(min-content, 1fr) auto
}
/* Each part of the game is positioned between grid lines by
* referencing the starting grid line and then specifying, if more
* than one, the number of rows or columns spanned to determine
* the ending grid line, which establishes bounds for the part. */
#title { grid-column: 1; grid-row: 1 }
#score { grid-column: 1; grid-row: 3 }
#stats { grid-column: 1; grid-row: 2; justify-self: start }
#board { grid-column: 2; grid-row: 1 / span 2; }
#controls { grid-column: 2; grid-row: 3; align-self: center }
</style>
<div id="grid">
<div id="title">Game Title</div>
<div id="score">Score</div>
<div id="stats">Stats</div>
<div id="board">Board</div>
<div id="controls">Controls</div>
</div></pre>
<h3 id=source-independence><span class=secno>1.3. </span> Source
Independence</h3>
<div class=sidefigure>
<p> <img alt="Image: An arrangement suitable for portrait orientation."
src="images/game-portrait.png">
<p class=caption>An arrangement suitable for ‘<code
class=css>portrait</code>’ orientation.
</div>
<div class=sidefigure>
<p> <img alt="Image: An arrangement suitable for landscape orientation."
src="images/game-landscape.png">
<p class=caption>An arrangement suitable for ‘<code
class=css>landscape</code>’ orientation.
</div>
<p> Continuing the prior example, the author also wants the game to adapt
to the space available on traditional computer monitors, handheld devices,
or tablet computers. Also, the game should optimize the placement of the
components when viewed either in landscape or portrait orientation
(Figures 4 and 5). By combining grid layout with media queries, the author
is able to use the same semantic markup, but rearrange the layout of
elements independent of their source order, to achieve the desired layout
in both orientations.
<p> The following example leverages grid layout’s ability to name the
space which will be occupied by a <a href="#grid-item"><i>grid
item</i></a>. This allows the author to avoid rewriting rules for <a
href="#grid-item"><i>grid items</i></a> as the grid’s definition
changes.
<pre class=example>
<style type="text/css">
@media (orientation: portrait) {
#grid {
display: grid;
/* The rows, columns and areas of the grid are defined visually
* using the grid-template property. Each string is a row, and
* each word an area. The number of words in a string
* determines the number of columns. Note the number of words
* in each string must be identical. */
grid-template: "title stats"
"score stats"
"board board"
"ctrls ctrls";
/* Columns and rows created with the template property can be
* assigned a sizing function with the grid-definition-columns
* and grid-definition-rows properties. */
grid-definition-columns: auto minmax(min-content, 1fr);
grid-definition-rows: auto auto minmax(min-content, 1fr) auto
}
}
@media (orientation: landscape) {
#grid {
display: grid;
/* Again the template property defines areas of the same name,
* but this time positioned differently to better suit a
* landscape orientation. */
grid-template: "title board"
"stats board"
"score ctrls";
grid-definition-columns: auto minmax(min-content, 1fr);
grid-definition-rows: auto minmax(min-content, 1fr) auto
}
}
/* The grid-area property places a grid item into a named
* region (area) of the grid. */
#title { grid-area: title }
#score { grid-area: score }
#stats { grid-area: stats }
#board { grid-area: board }
#controls { grid-area: ctrls }
</style>
<div id="grid">
<div id="title">Game Title</div>
<div id="score">Score</div>
<div id="stats">Stats</div>
<div id="board">Board</div>
<div id="controls">Controls</div>
</div></pre>
<h3 id=grid-layering><span class=secno>1.4. </span> Grid Layering of
Elements</h3>
<div class=sidefigure>
<p> <img alt="Image: A control composed of layered HTML elements."
src="images/control-layering-and-alignment.png">
<p class=caption>A control composed of layered HTML elements.
</div>
<p> In the example shown in Figure 6, the author is creating a custom
slider control. The control has six parts. The lower and upper labels
align to the left and right edges of the control. The track of the slider
spans the area between the labels. The lower and upper fill parts touch
beneath the thumb, and the thumb is a fixed width and height that can be
moved along the track by updating the two flex-sized columns.
<p> Prior to the introduction of grid layout, the author would have likely
used absolute positioning to control the top and left coordinates, along
with the width and height of each HTML element that comprises the control.
By leveraging grid layout, the author can instead limit script usage to
handling mouse events on the thumb, which snaps to various positions along
the track as the ‘<a href="#grid-definition-columns"><code
class=property>grid-definition-columns</code
10986
></a>’ property of the <a
href="#grid-container"><i>grid container</i></a> is updated.
<pre class=example>
<style type="text/css">
#grid {
display: grid;
/* The grid-definition-columns and rows properties also support
* naming grid lines which can then be used to position grid
* items. The line names are assigned on either side of a column
* or row sizing function where the line would logically exist. */
grid-definition-columns:
"start" auto
"track-start" 0.5fr
"thumb-start" auto
"fill-split" auto
"thumb-end" 0.5fr
"track-end" auto
"end";
}
/* The grid-placement properties accept named lines. Below the
* lines are referred to by name. Beyond any
* semantic advantage, the names also allow the author to avoid
* renumbering the grid-start and grid-before properties of the
* grid items. This is similar to the concept demonstrated in the
* prior example with the grid-template property during orientation
* changes, but grid lines can also work with layered grid items
* that have overlapping areas of different shapes like the thumb
* and track parts in this example. */
#lower-label { grid-start: "start" }
#track { grid-column: "track-start" / "track-end"; align-self: center }
#upper-label { grid-end: "end"; }
/* Fill parts are drawn above the track so set z-index to 5. */
#lower-fill { grid-column: "track-start" / "fill-split";
align-self: end;
z-index: 5 }
#upper-fill { grid-column: "fill-split" / "track-end";
align-self: start;
z-index: 5 }
/* Thumb is the topmost part; assign it the highest z-index value. */
#thumb { grid-column: "thumb-start" / "thumb-end"; z-index: 10 }
</style>
<div id="grid">
<div id="lower-label">Lower Label</div>
<div id="upper-label">Upper Label</div>
<div id="track">Track</div>
<div id="lower-fill">Lower Fill</div>
<div id="upper-fill">Upper Fill</div>
<div id="thumb">Thumb</div>
</div></pre>
<h2 id=grid-concepts><span class=secno>2. </span> Grid Layout Concepts and
Terminology</h2>
<p> In <dfn id=grid-layout>grid layout</dfn>, the content of a <a
href="#grid-container"><i>grid container</i></a> is laid out by
positioning and aligning it into a <a
href="#display-grid"><i>grid</i></a>. The <dfn id=grid>grid</dfn> is an
intersecting set of horizontal and vertical <a href="#grid-line"><i>grid
lines</i></a> that divides the <a href="#grid-container"><i>grid
container</i></a>’s space into <a href="#grid-area"><i>grid
areas</i></a>, into which <a href="#grid-item"><i>grid items</i></a>
(representing the <a href="#grid-container"><i>grid container</i></a>’s
content) can be placed. There are two sets of <a href="#grid-line"><i>grid
lines</i></a>: one set defining <dfn id=columns
title="grid column | column">columns</dfn> that run along the <a
href="http://www.w3.org/TR/css3-writing-modes/#block-axis">block axis</a>,
and an orthogonal set defining <dfn id=rows
title="grid row | row">rows</dfn> along the <a
href="http://www.w3.org/TR/css3-writing-modes/#inline-axis">inline
axis</a>. <a href="#CSS3-WRITING-MODES"
rel=biblioentry>[CSS3-WRITING-MODES]<!--{{!CSS3-WRITING-MODES}}--></a>
<!--
<div class="figure">
<img class="figure" alt="Image: A diagram illustrating the relationship between the Grid Element and its Tracks, Lines, Areas and Items." src="images/grid-concepts.png" />
<p class="caption">A diagram illustrating the relationship between the <i>grid container</i> and its tracks, lines, areas and items.
</div>
-->
<div class=figure> <img alt="Image: Grid Lines." class=figure
src="images/grid-lines.png">
<p class=caption>Grid lines: Three in the block axis and four in the
inline axis.
</div>
<h3 id=grid-track-concept><span class=secno>2.1. </span> Grid Tracks</h3>
<p> <dfn id=grid-track>Grid track</dfn> is a generic term for a <a
href="#columns"><i>grid column</i></a> or <a href="#rows"><i>grid
row</i></a>—in other words, it is the space between two adjacent <a
href="#grid-line"><i>grid lines</i></a>. Each <a
href="#grid-track"><i>grid track</i></a> is assigned a sizing function,
which controls how wide or tall the column or row may grow, and thus how
far apart its bounding <a href="#grid-line"><i>grid lines</i></a> are.
<div class=example>
<p> In the following example there are two columns and three rows. The
first column is fixed at 150px. The second column uses flexible sizing,
which is a function of the unassigned space in the Grid, and thus will
vary as the width of the <a href="#grid-container"><i>grid
container</i></a> changes. If the used width of the <a
href="#grid-container"><i>grid container</i></a> is 200px, then the
second column 50px wide. If the used width of the <i>grid element</i> is
100px, then the second column is 0px and any content positioned in the
column will overflow the <a href="#grid-container"><i>grid
container</i></a>.
<pre>
<style type="text/css">
#grid {
display: grid;
grid-definition-columns: 150px 1fr; /* two columns */
grid-definition-rows: 50px 1fr 50px /* three rows */
}
</style></pre>
</div>
<h3 id=grid-line-concept><span class=secno>2.2. </span> Grid Lines</h3>
<p> <dfn id=grid-line title="grid line|grid row line|grid column line">Grid
lines</dfn> are the horizontal and vertical dividing lines of the <a
href="#display-grid"><i>grid</i></a>. A <a href="#grid-line"><i>grid
line</i></a> exists on either side of a column or row. They can be
referred to by numerical index, or by an author-specified name. A <a
href="#grid-item"><i>grid item</i></a> references the <a
href="#grid-line"><i>grid lines</i></a> to determine its position within
the <a href="#display-grid"><i>grid</i></a> using the <a
href="#placement">grid-placement properties</a>.
<div class=example>
<p> The following two examples create three column <a
href="#grid-line"><i>grid lines</i></a> and four row <a
href="#grid-line"><i>grid lines</i></a>. The first example demonstrates
how an author would position a <a href="#grid-item"><i>grid item</i></a>
using <a href="#grid-line"><i>grid line</i></a> numbers. The second
example uses explicitly named <a href="#grid-line"><i>grid lines</i></a>.
<pre>
<style type="text/css">
#grid {
display: grid;
grid-definition-columns: 150px 1fr;
grid-definition-rows: 50px 1fr 50px
}
#item1 { grid-column: 2;
grid-start: 1; grid-end: 1; }
</style></pre>
<pre>
<style type="text/css">
/* equivalent layout to the prior example, but using named lines */
#grid {
display: grid;
grid-definition-columns: 150px "item1-start" 1fr "item1-end";
grid-definition-rows: "item1-start" 50px 1fr 50px "item1-end"
}
#item1 {
grid-column: "item1-start" / "item1-end";
grid-row: "item1-start" / "item1-end"
}
</style></pre>
</div>
<h3 id=grid-area-concept><span class=secno>2.3. </span> Grid Areas</h3>
<p> A <dfn id=grid-area>grid area</dfn> is the logical space used to lay
out one or more <a href="#grid-item"><i>grid items</i></a>. It is bound by
four <a href="#grid-line"><i>grid lines</i></a>, one on each side of the
<a href="#grid-area"><i>grid area</i></a>, and participates in the sizing
of the <a href="#grid-track"><i>grid tracks</i></a> it intersects. A <a
href="#grid-area"><i>grid area</i></a> can be named explicitly using the
‘<a href="#grid-template"><code
class=property>grid-template</code></a>’ property of the <a
href="#grid-container"><i>grid container</i></a>, or referenced implicitly
by its bounding <a href="#grid-line"><i>grid lines</i></a>. A <a
href="#grid-item"><i>grid item</i></a> is assigned to a <a
href="#grid-area"><i>grid area</i></a> using the <a
href="#placement">grid-placement properties</a>.
<pre class=example>
<style type="text/css">
/* using the template syntax */
#grid {
display: grid;
grid-template: ". a"
"b a"
". a";
grid-definition-columns: 150px 1fr;
grid-definition-rows: 50px 1fr 50px
}
#item1 { grid-area: a }
#item2 { grid-area: b }
#item3 { grid-area: b }
/* Align items 2 and 3 at different points in the Grid Area "b". */
/* By default, Grid Items are stretched to fit their Grid Area */
/* and these items would layer one over the other. */
#item2 { align-self: head }
#item3 { justify-self: end; align-self: foot }
</style></pre>
<p> A <a href="#grid-item"><i>grid item</i></a>’s <a
href="#grid-area"><i>grid area</i></a> forms the containing block into
which it is laid out. Percentage lengths specified on a <a
href="#grid-item"><i>grid item</i></a> resolve against this containing
block. Percentages specified for ‘<code
class=property>margin-top</code>’, ‘<code
class=property>padding-top</code>’, ‘<code
class=property>margin-bottom</code>’, and ‘<code
class=property>padding-bottom</code>’ on a <a href="#grid-item"><i>grid
item</i></a> resolve against the height of its containing block, rather
than the width (as for blocks).
<p> <a href="#grid-item"><i>Grid items</i></a> placed into the same <a
href="#grid-area"><i>grid area</i></a> do not directly affect each other's
layout. Indirectly, a <a href="#grid-item"><i>grid item</i></a> can affect
the position of a <a href="#grid-line"><i>grid line</i></a> in a column or
row that uses a contents-based relative size, which in turn can affect the
position or size of another <a href="#grid-item"><i>grid item</i></a>.
<h2 id=grid-model><span class=secno>3. </span> Grid Layout Box Model</h2>
<h3 id=grid-containers><span class=secno>3.1. </span> Grid Containers: the
‘<a href="#display-grid"><code class=css>grid</code></a>’ and ‘<a
href="#display-inline-grid"><code class=css>inline-grid</code></a>’
‘<code class=property>display</code>’ values</h3>
<table class=propdef>
<tbody>
<tr>
<th>Name:
<td>display
<tr>
<th><a href="#values">New Values</a>:
<td>grid | inline-grid
</table>
<dl>
<dt><dfn id=display-grid>‘<code class=css>grid</code>’</dfn>
<dd> This value causes an element to generate a block-level <a
href="#grid-container"><i>grid container</i></a> box.
<dt><dfn id=display-inline-grid>‘<code
class=css>inline-grid</code>’</dfn>
<dd> This value causes an element to generate an inline-level <a
href="#grid-container"><i>grid container</i></a> box.
</dl>
<p> A <dfn id=grid-container>grid container</dfn> establishes a new <dfn
id=grid-formatting-context>grid formatting context</dfn> for its contents.
This is the same as establishing a block formatting context, except that
grid layout is used instead of block layout: floats do not intrude into
the grid container, and the grid container's margins do not collapse with
the margins of its contents. <a href="#grid-container"><i>Grid
containers</i></a> form a containing block for their contents <a
href="http://www.w3.org/TR/CSS21/visudet.html#containing-block-details">exactly
like block containers do</a>. <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> The ‘<code
class=property>overflow</code>’ property applies to <a
href="#grid-container"><i>grid containers</i></a>.
<p> Grid containers are not block containers, and so some properties that
were designed with the assumption of block layout don't apply in the
context of grid layout. In particular:
<ul>
<li> all of the ‘<code class=css>column-*</code>’ properties in the
Multicol module have no effect on a grid container.
<li> ‘<code class=property>float</code>’ and ‘<code
class=property>clear</code>’ have no effect on a <a
href="#grid-item"><i>grid item</i></a>. (However, the ‘<code
class=property>float</code>’ property still affects the computed value
of ‘<code class=property>display</code>’ on children of a grid
container, as this occurs <em title="">before</em> <a
href="#grid-item"><i>grid items</i></a> are determined.)
<li> ‘<code class=property>vertical-align</code>’ has no effect on a
grid item.
<li> the ‘<code class=css>::first-line</code>’ and ‘<code
class=css>::first-letter</code>’ pseudo-elements do not apply to <a
href="#grid-container"><i>grid containers</i></a>.
</ul>
<p> If an element's specified ‘<code class=property>display</code>’ is
‘<a href="#display-inline-grid"><code
class=css>inline-grid</code></a>’ and the element is floated or
absolutely positioned, the computed value of ‘<code
class=property>display</code>’ is <a href="#display-grid">‘<code
class=css>grid</code>’</a>. The table in <a
href="http://www.w3.org/TR/CSS2/visuren.html#dis-pos-flo">CSS 2.1 Chapter
9.7</a> is thus amended to contain an additional row, with ‘<a
href="#display-inline-grid"><code class=css>inline-grid</code></a>’ in
the "Specified Value" column and <a href="#display-grid">‘<code
class=css>grid</code>’</a> in the "Computed Value" column.
<h3 id=subgrids-the-subgrid-display-value><span class=secno>3.2.
</span>Subgrids: the ‘<code class=css>subgrid</code>’ ‘<code
class=property>display</code>’ value</h3>
<div class=issue> This is a proposal to address the alignment of sub-items
across grid items, so that, for example, a grid of labels + inputs (with
each pair styled as a unit) can still align the individual elements in a
greater grid. Potential issues:
<ul>
<li> If an item is positioned outside the subgrid's declared
rows/columns, does the subgrid expand further into the outer grid, or
just overflow within its declared bounds?
<li> How to declare a subgrid? As a separate display type, as illustrated
here, or by assigning a "subgrid" value to grid-definition-rows/columns
(which would allow aligning to the parent grid in only one dimension)?
<li> Can auto-placement in the subgrid determine/increase the size of the
subgrid?
<li> Should you be able to interleave lines from the parent grid with
subgrid lines?
</ul>
</div>
<p> A <a href="#grid-item"><i>grid item</i></a> can itself be a <a
href="#grid-container"><i>grid container</i></a> by giving it ‘<code
class=css>display: grid</code>’; in this case the layout of its contents
will be independent of the layout of the grid it participates in.
<p> In some cases it might be necessary for the contents of multiple <a
href="#grid-item"><i>grid items</i></a> to align to each other; in this
case ‘<code class=css>display: subgrid</code>’ can be used. A <a
href="#grid-item"><i>grid item</i></a> with ‘<code class=css>display:
subgrid</code>’ behaves just like one with ‘<code class=css>display:
grid</code>’ except that:
<ul>
<li> The ‘<a href="#grid-definition-columns"><code
class=property>grid-definition-columns</code></a>’ and ‘<code
class=property>grid-definition-row</code>’ properties do not apply.
Instead the number of explicit tracks is given by its <a
href="#grid-span"><i>grid span</i></a>.
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