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<!DOCTYPE html><html lang=en><head>
<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
<title>CSS Grid Layout Module Level 1</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-ED rel=stylesheet type=text/css>
</head>
<body class=h-entry>
<style scoped 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>
<div class=he
9E7F
ad>
<p data-fill-with=logo><a class=logo href=http://www.w3.org/>
<img alt=W3C height=48 src=http://www.w3.org/Icons/w3c_home width=72>
</a></p>
<h1 class="p-name no-ref" id=title>CSS Grid Layout Module Level 1</h1>
<h2 class="no-num no-toc no-ref" id=subtitle><span class=content>Editor's Draft,
<span class=dt-updated><span class=value-title title=20130819>19 August 2013</span></span></span></h2>
<div data-fill-with=spec-metadata><dl><dt>This version:<dd><a class=u-url href=http://dev.w3.org/csswg/css-grid/>http://dev.w3.org/csswg/css-grid/</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/css-grid/>http://dev.w3.org/csswg/css-grid/</a>
<dt>Feedback:</dt>
<dd><a href="mailto:www-style@w3.org?subject=%5Bcss-grid%5D%20feedback">www-style@w3.org</a>
with subject line
“<kbd>[css-grid] <var>… message topic …</var></kbd>”
(<a href=http://lists.w3.org/Archives/Public/www-style/ rel=discussion>archives</a>)<dt>Test Suite:<dd>None Yet<dt>Editors:
<dd class="p-author h-card vcard"><a class="p-name fn u-url url" href=http://www.xanthir.com/contact/>Tab Atkins Jr.</a> (<span class="p-org org">Google</span>)<dd class="p-author h-card vcard"><a class="p-name fn u-url url" href=http://fantasai.inkedblade.net/contact>fantasai</a> (<span class="p-org org">Mozilla</span>)<dd class="p-author h-card vcard"><a class="p-name fn u-email email" href=mailto:ratan@microsoft.com>Rossen Atanassov</a> (<span class="p-org org">Microsoft</span>)<dt>Previous 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<dt>Previous version:<dd>http://www.w3.org/TR/2013/WD-css3-grid-layout-20130402/<dd>http://www.w3.org/TR/2012/WD-css3-grid-layout-20121106/<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></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> © 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>
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc no-ref" id=abstract><span class=content>Abstract</span></h2>
<p class=p-summary data-fill-with=abstract>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.
<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.</p>
<h2 class="no-num no-toc no-ref" id=status><span class=content>Status of this document</span></h2>
<div data-fill-with=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=%5Bcss-grid%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 “css-grid” in the subject,
preferably like this:
“[css-grid] <em>…summary of comment…</em>”
<p>
This document was produced by the <a href=/Style/CSS/members>CSS Working Group</a>
(part of the <a href=/Style/>Style Activity</a>).
<p>
This document was produced by a group operating under
the <a href=/Consortium/Patent-Policy-20040205/>5 February 2004 W3C Patent Policy</a>.
W3C maintains a <a href=/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=/Consortium/Patent-Policy-20040205/#def-essential>Essential Claim(s)</a>
must disclose the information in accordance with <a href=/Consortium/Patent-Policy-20040205/#sec-Disclosure>section 6 of the W3C Patent Policy</a>.</div>
<div data-fill-with=at-risk></div>
<h2 class="no-num no-toc no-ref" id=contents><span class=content>Table of contents</span></h2>
<div data-fill-with=table-of-contents><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 and Cells</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 <span data-link-type=value>grid</span> and <span class=css data-link-type=maybe>inline-grid</span> <span class=property data-link-type=propdesc title=display>display</span> values</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 <span class=property data-link-type=propdesc title=visibility>visibility</span> property</a><li><a href=#order-property><span class=secno>4.4</span>
Reordered Grid Items: the <span class=property data-link-type=propdesc title=order>order</span> property</a></ul><li><a href=#grid-definition><span class=secno>5</span>
The Explicit Grid</a><ul class=toc><li><a href=#track-sizing><span class=secno>5.1</span>
Track Sizing: the <span class=property data-link-type=propdesc title=grid-template-rows>grid-template-rows</span> and <span class=property data-link-type=propdesc title=grid-template-columns>grid-template-columns</span> properties</a><ul class=toc><li><a href=#named-lines><span class=secno>5.1.1</span>
Named Grid Lines: the <span class=css data-link-type=maybe>(<span class=production data-link-type=type><ident></span>*)</span> syntax</a><li><a href=#repeat-notation><span class=secno>5.1.2</span>
Repeating Rows and Columns: the <span class=css data-link-type=maybe>repeat()</span> notation</a><li><a href=#fr-unit><span class=secno>5.1.3</span>
Flexible Lengths: the <span class=css data-link-type=maybe>fr</span> unit</a><li><a href=#subgrids><span class=secno>5.1.4</span>
Subgrids: the <span data-link-for=grid-template-rows data-link-type=value>subgrid</span> keyword</a><li><a href=#resolved-track-list><span class=secno>5.1.5</span>
Resolved Values</a></ul><li><a href=#grid-template-areas-property><span class=secno>5.2</span>
Named Areas: the <span class=property data-link-type=propdesc title=grid-template-areas>grid-template-areas</span> property</a><ul class=toc><li><a href=#implicit-named-lines><span class=secno>5.2.1</span>
Implicit Named Lines</a></ul><li><a href=#explicit-grid-shorthand><span class=secno>5.3</span>
Grid Definition Shorthand: the <span class=property data-link-type=propdesc title=grid-template>grid-template</span> property</a></ul><li><a href=#implicit-grids><span class=secno>6</span>
The Implicit Grid</a><ul class=toc><li><a href=#auto-tracks><span class=secno>6.1</span>
Sizing Auto-generated Rows and Columns: the <span class=property data-link-type=propdesc title=grid-auto-rows>grid-auto-rows</span> and <span class=property data-link-type=propdesc title=grid-auto-columns>grid-auto-columns</span> properties</a><li><a href=#grid-auto-flow-property><span class=secno>6.2</span>
Automatic Placement: the <span class=property data-link-type=propdesc title=grid-auto-flow>grid-auto-flow</span> property</a><ul class=toc><li><a href=#auto-placement-algo><span class=secno>6.2.1</span>
Automatic Grid Item Placement Algorithm</a></ul><li><a href=#implicit-grid-shorthand><span class=secno>6.3</span>
Implicit Grid Shorthand: the <span class=property data-link-type=propdesc title=grid-auto>grid-auto</span> property</a></ul><li><a href=#placement><span class=secno>7</span>
Placing Grid Items</a><ul class=toc><li><a href=#line-placement><span class=secno>7.1</span>
Line-based Placement: the <span class=property data-link-type=propdesc title=grid-row-start>grid-row-start</span>, <span class=property data-link-type=propdesc title=grid-column-start>grid-column-start</span>, <span class=property data-link-type=propdesc title=grid-row-end>grid-row-end</span>, and <span class=property data-link-type=propdesc title=grid-column-end>grid-column-end</span> properties</a><li><a href=#placement-shorthands><span class=secno>7.2</span>
Placement Shorthands: the <span class=property data-link-type=propdesc title=grid-column>grid-column</span>, <span class=property data-link-type=propdesc title=grid-row>grid-row</span>, and <span class=property data-link-type=propdesc title=grid-area>grid-area</span> properties</a></ul><li><a href=#alignment><span class=secno>8</span>
Alignment</a><ul class=toc><li><a href=#auto-margins><span class=secno>8.1</span>
Aligning with <span data-link-for=margin data-link-type=value>auto</span> margins</a><li><a href=#row-align><span class=secno>8.2</span>
Row-axis Alignment: the <span class=property data-link-type=propdesc title=justify-self>justify-self</span> and <span class=property data-link-type=propdesc title=justify-items>justify-items</span> properties</a><li><a href=#column-align><span class=secno>8.3</span>
Column-axis Alignment: the <span class=property data-link-type=propdesc title=align-self>align-self</span> and <span class=property data-link-type=propdesc title=align-items>align-items</span> properties</a><li><a href=#z-order><span class=secno>8.4</span>
Z-axis Ordering: the <span class=property data-link-type=propdesc title=z-index>z-index</span> property</a><li><a href=#grid-baselines><span class=secno>8.5</span>
Grid Baselines</a></ul><li><a href=#layout-algorithm><span class=secno>9</span>
Grid Layout Algorithm</a><ul class=toc><li><a href=#algo-terms><span class=secno>9.1</span>
Definition of Terms for use in Calculating Grid Track Sizes</a><li><a href=#grid-track-sizing-algorithm><span class=secno>9.2</span>
Grid Track Sizing Algorithm</a><li><a href=#shrink-to-fit><span class=secno>9.3</span>
Defining the Shrink-to-fit Behavior of Grid Elements</a></ul><li><a href=#pagination><span class=secno>10</span>
Fragmenting Grid Layout</a><li><a href=#acknowledgements><span class=secno></span>
Acknowledgements</a><li><a href=#changes><span class=secno></span>
Changes</a><li><a href=#conformance><span class=secno></span>
Conformance</a><ul class=toc><li><a href=#conventions><span class=secno></span>
Document conventions</a><li><a href=#conformance-classes><span class=secno></span>
Conformance classes</a><li><a href=#partial><span class=secno></span>
Partial implementations</a><li><a href=#experimental><span class=secno></span>
Experimental implementations</a><li><a href=#testing><span class=secno></span>
Non-experimental implementations</a></ul><li><a href=#references><span class=secno></span>
References</a><ul class=toc><li><a href=#normative><span class=secno></span>
Normative References</a><li><a href=#informative><span class=secno></span>
Informative References</a></ul><li><a href=#index><span class=secno></span>
Index</a><li><a href=#property-index><span class=secno></span>
Property index</a></ul></div>
<h2 data-level=1 id=intro><span class=secno>1 </span><span class=content>
Introduction and Overview</span><a class=section-link href=#intro>§</a></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.
<h3 data-level=1.1 id=background><span class=secno>1.1 </span><span class=content>
Background and Motivation</span><a class=section-link href=#background>§</a></h3>
<div class=sidefigure>
<amg 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.
</amg></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>grid areas</a> defined by these columns and rows.
Figure 1 illustrates a basic layout which can be achieved with grid layout.
<h3 data-level=1.2 id=adapting-to-available-space><span class=secno>1.2 </span><span class=content>
Adapting Layouts to Available Space</span><a class=section-link href=#adapting-to-available-space>§</a></h3>
<div class=sidefigure>
<p>
<amg alt="Image: Five grid items arranged according to content size and available space." src=images/game-smaller.png>
</amg><p class=caption>
Five grid items arranged according to content size and available space.
</div>
<div class=sidefigure>
<p>
<amg alt="Image: Growth in the grid due to an increase in available space." src=images/game-larger.png>
</amg><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:
<p> <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>grid items</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>grid item</a>
using the <a class=property data-link-type=propdesc href=#propdef-grid-template-rows title=grid-template-rows>grid-template-rows</a> and <a class=property data-link-type=propdesc href=#propdef-grid-template-columns title=grid-template-columns>grid-template-columns</a> properties on the <a href=#grid-container>grid container</a>,
and the <a class=property data-link-type=propdesc href=#propdef-grid-row title=grid-row>grid-row</a> and <a class=property data-link-type=propdesc href=#propdef-grid-column title=grid-column>grid-column</a> properties on each <a href=#grid-item>grid item</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-template-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-template-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 data-level=1.3 id=source-independence><span class=secno>1.3 </span><span class=content>
Source Independence</span><a class=section-link href=#source-independence>§</a></h3>
<div class=sidefigure>
<p>
<amg alt="Image: An arrangement suitable for portrait orientation." src=images/game-portrait.png>
</amg><p class=caption>An arrangement suitable for <span class=css data-link-type=maybe>portrait</span> orientation.
</div>
<div class=sidefigure>
<p>
<amg alt="Image: An arrangement suitable for landscape orientation." src=images/game-landscape.png>
</amg><p class=caption>An arrangement suitable for <span class=css data-link-type=maybe>landscape</span> 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>grid item</a>.
This allows the author to avoid rewriting rules for <a href=#grid-item>grid items</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-areas 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-areas: "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-template-columns
* and grid-template-rows properties. */
grid-template-columns: auto minmax(min-content, 1fr);
grid-template-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-areas: "title board"
"stats board"
"score ctrls";
grid-template-columns: auto minmax(min-content, 1fr);
grid-template-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 data-level=1.4 id=grid-layering><span class=secno>1.4 </span><span class=content>
Grid Layering of Elements</span><a class=section-link href=#grid-layering>§</a></h3>
<div class=sidefigure>
<p>
<amg alt="Image: A control composed of layered HTML elements." src=images/control-layering-and-alignment.png>
</amg><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 class=property data-link-type=propdesc href=#propdef-grid-template-columns title=grid-template-columns>grid-template-columns</a> property of the <a href=#grid-container>grid container</a> is updated.
<pre class=example><style type="text/css">
#grid {
display: grid;
/* The grid-template-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-template-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-column-start and grid-row-start properties of the
* grid items. This is similar to the concept demonstrated in the
* prior example with the grid-template-areas 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-column-start: start }
#track { grid-column: track-start / track-end; align-self: center }
#upper-label { grid-column-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 data-level=2 id=grid-concepts><span class=secno>2 </span><span class=content>
Grid Layout Concepts and Terminology</span><a class=section-link href=#grid-concepts>§</a></h2>
<p>
In <dfn data-dfn-type=dfn data-export="" id=grid-layout>grid layout</dfn>,
the content of a <a href=#grid-container>grid container</a> is laid out
by positioning and aligning it into a <a href=#grid>grid</a>.
The <dfn data-dfn-type=dfn data-export="" id=grid>grid</dfn> is an intersecting set of horizontal and vertical <a href=#grid-line>grid lines</a>
that divides the <a href=#grid-container>grid container</a>’s space into <a href=#grid-area>grid areas</a>,
into which <a href=#grid-item>grid items</a> (representing the <a href=#grid-container>grid container</a>’s content) can be placed.
There are two sets of <a href=#grid-line>grid lines</a>:
one set defining <dfn data-dfn-type=dfn data-export="" 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> (the <dfn data-dfn-type=dfn data-export="" id=column-axis>column axis</dfn>,
and an orthogonal set defining <dfn data-dfn-type=dfn data-export="" 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> (the <dfn data-dfn-type=dfn data-export="" id=row-axis>row axis</dfn>).
<a data-biblio-type=normative data-link-type=biblio href=#css3-writing-modes title=CSS3-WRITING-MODES>[CSS3-WRITING-MODES]</a>
<!--
<div class="figure">
<amg 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 <a>grid container</a> and its tracks, lines, areas and items.
</div>
-->
<div class=figure>
<amg 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.
</amg></div>
<h3 data-level=2.1 id=grid-track-concept><span class=secno>2.1 </span><span class=content>
Grid Tracks and Cells</span><a class=section-link href=#grid-track-concept>§</a></h3>
<p>
<dfn data-dfn-type=dfn data-export="" id=grid-track>Grid track</dfn> is a generic term for a <a href=#columns>grid column</a> or <a href=#rows>grid row</a>—in
other words, it is the space between two adjacent <a href=#grid-line>grid lines</a>.
Each <a href=#grid-track>grid track</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>grid lines</a> are.
<p>
A <dfn data-dfn-type=dfn data-export="" id=grid-cell>grid cell</dfn> is the similar term for the full grid—it
is the space between two adjacent row and two adjacent column <a href=#grid-line>grid lines</a>.
It is the smallest unit of the grid that can be referenced when positioning <a href=#grid-item>grid items</a>.
<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>grid container</a> changes.
If the used width of the <a href=#grid-container>grid container</a> is 200px, then the second column 50px wide.
If the used width of the <a href=#grid-container>grid container</a> is 100px, then the second column is 0px
and any content positioned in the column will overflow the <a href=#grid-container>grid container</a>.
<pre><style type="text/css">
#grid {
display: grid;
grid-template-columns: 150px 1fr; /* two columns */
grid-template-rows: 50px 1fr 50px /* three rows */
}
</style></pre> </div>
<h3 data-level=2.2 id=grid-line-concept><span class=secno>2.2 </span><span class=content>
Grid Lines</span><a class=section-link href=#grid-line-concept>§</a></h3>
<p>
<dfn data-dfn-type=dfn data-export="" 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=#grid>grid</a>.
A <a href=#grid-line>grid line</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>grid item</a> references the <a href=#grid-line>grid lines</a> to determine its position within the <a href=#grid>grid</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>grid lines</a> and four row <a href=#grid-line>grid lines</a>.
The first example demonstrates how an author would position a <a href=#grid-item>grid item</a> using <a href=#grid-line>grid line</a> numbers.
The second example uses explicitly named <a href=#grid-line>grid lines</a>.
<pre><style type="text/css">
#grid {
display: grid;
grid-template-columns: 150px 1fr;
grid-template-rows: 50px 1fr 50px
}
#item1 { grid-column: 2;
grid-column-start: 1; grid-column-end: 1; }
</style></pre>
<pre><style type="text/css">
/* equivalent layout to the prior example, but using named lines */
#grid {
display: grid;
grid-template-columns: 150px (item1-start) 1fr (item1-end);
grid-template-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 data-level=2.3 id=grid-area-concept><span class=secno>2.3 </span><span class=content>
Grid Areas</span><a class=section-link href=#grid-area-concept>§</a></h3>
<p>
A <dfn data-dfn-type=dfn data-export="" id=grid-area>grid area</dfn> is the logical space used to lay out one or more <a href=#grid-item>grid items</a>.
It is bound by four <a href=#grid-line>grid lines</a>, one on each side of the <a href=#grid-area>grid area</a>,
and participates in the sizing of the <a href=#grid-track>grid tracks</a> it intersects.
A <a href=#grid-area>grid area</a> can be named explicitly using the <a class=property data-link-type=propdesc href=#propdef-grid-template-areas title=grid-template-areas>grid-template-areas</a> property of the <a href=#grid-container>grid container</a>,
or referenced implicitly by its bounding <a href=#grid-line>grid lines</a>.
A <a href=#grid-item>grid item</a> is assigned to a <a href=#grid-area>grid area</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-areas: ". a"
"b a"
". a";
grid-template-columns: 150px 1fr;
grid-template-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>grid item</a>’s <a href=#grid-area>grid area</a> forms the containing block into which it is laid out.
Percentage lengths specified on a <a href=#grid-item>grid item</a> resolve against this containing block.
Percentages specified for <a class=property data-link-type=propdesc href=http://www.w3.org/TR/CSS21/box.html#propdef-margin-top title=margin-top>margin-top</a>, <a class=property data-link-type=propdesc href=http://www.w3.org/TR/CSS21/box.html#propdef-padding-top title=padding-top>padding-top</a>, <a class=property data-link-type=propdesc href=http://www.w3.org/TR/CSS21/box.html#propdef-margin-bottom title=margin-bottom>margin-bottom</a>, and <a class=property data-link-type=propdesc href=http://www.w3.org/TR/CSS21/box.html#propdef-padding-bottom title=padding-bottom>padding-bottom</a> on a <a href=#grid-item>grid item</a>
resolve against the height of its containing block,
rather than the width (as for blocks).
<p>
<a href=#grid-item>Grid items</a> placed into the same <a href=#grid-area>grid area</a> do not directly affect each other's layout.
Indirectly, a <a href=#grid-item>grid item</a> can affect the position of a <a href=#grid-line>grid line</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>grid item</a>.
<h2 data-level=3 id=grid-model><span class=secno>3 </span><span class=content>
Grid Layout Box Model</span><a class=section-link href=#grid-model>§</a></h2>
<h3 data-level=3.1 id=grid-containers><span class=secno>3.1 </span><span class=content>
Grid Containers: the <a data-link-type=value href=#valuedef-grid>grid</a> and <a class=css data-link-type=maybe href=#valuedef-inline-grid>inline-grid</a> <a class=property data-link-type=propdesc href=#propdef-display title=display>display</a> values</span><a class=section-link href=#grid-containers>§</a></h3>
<table class=propdef><tr><th>Name:<td><dfn data-dfn-type=property data-export="" id=propdef-display>display</dfn><tr><th>New Values:<td>grid | inline-grid</table>
<dl data-dfn-for=display data-dfn-type=value>
<dt><dfn data-dfn-for=display data-dfn-type=value data-export="" id=valuedef-grid>grid</dfn>
<dd>
This value causes an element to generate a block-level <a href=#grid-container>grid container</a> box.
<dt><dfn data-dfn-for=display data-dfn-type=value data-export="" id=valuedef-inline-grid>inline-grid</dfn>
<dd>
This value causes an element to generate an inline-level <a href=#grid-container>grid container</a> box.
</dl>
<p>
A <dfn data-dfn-type=dfn data-export="" id=grid-container>grid container</dfn> establishes a new <dfn data-dfn-type=dfn data-export="" 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>Grid containers</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 data-biblio-type=normative data-link-type=biblio href=#css21 title=CSS21>[CSS21]</a>
The <a class=property data-link-type=propdesc href=http://dev.w3.org/csswg/css-overflow-3/#overflow title=overflow>overflow</a> property applies to <a href=#grid-container>grid containers</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:
<p> <ul>
<li>
all of the <a class=property data-link-type=propdesc title=column-*>column-*</a> properties in the Multicol module have no effect on a grid container.
<li>
<a class=property data-link-type=propdesc href=http://www.w3.org/TR/CSS21/visuren.html#propdef-float title=float>float</a> and <a class=property data-link-type=propdesc href=http://www.w3.org/TR/CSS21/visuren.html#propdef-clear title=clear>clear</a> have no effect on a <a href=#grid-item>grid item</a>.
(However, the <a class=property data-link-type=propdesc href=http://www.w3.org/TR/CSS21/visuren.html#propdef-float title=float>float</a> property still affects the computed value of <a class=property data-link-type=propdesc href=#propdef-display title=display>display</a> on children of a grid container,
as this occurs <em title="">before</em> <a href=#grid-item>grid items</a> are determined.)
<li>
<a class=property data-link-type=propdesc href=http://www.w3.org/TR/CSS21/visudet.html#propdef-vertical-align title=vertical-align>vertical-align</a> has no effect on a grid item.
<li>
the <span class=css data-link-type=maybe>::first-line</span> and <span class=css data-link-type=maybe>::first-letter</span> pseudo-elements do not apply to <a href=#grid-container>grid containers</a>.
</ul>
<p>
If an element's specified <a class=property data-link-type=propdesc href=#propdef-display title=display>display</a> is <a class=css data-link-type=maybe href=#valuedef-inline-grid>inline-grid</a>
and the element is floated or absolutely positioned,
the computed value of <a class=property data-link-type=propdesc href=#propdef-display title=display>display</a> is <a data-link-type=value href=#valuedef-grid>grid</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 class=css data-link-type=maybe href=#valuedef-inline-grid>inline-grid</a> in the "Specified Value" column
and <a href=#grid>grid</a> in the "Computed Value" column.
<h2 data-level=4 id=grid-items><span class=secno>4 </span><span class=content>
Grid Items</span><a class=section-link href=#grid-items>§</a></h2>
<p>
The contents of a <a href=#grid-container>grid container</a> consists of zero or more <dfn data-dfn-type=dfn data-export="" id=grid-item title="grid item">grid items</dfn>:
each child of a <a href=#grid-container>grid container</a>
becomes a <a href=#grid-item>grid item</a>,
and each contiguous run of text that is directly contained inside a <a href=#grid-container>grid container</a>
is wrapped in an anonymous <a href=#grid-item>grid item</a>.
However, an anonymous grid item that contains only
<a href=http://www.w3.org/TR/CSS21/text.html#white-space-prop>white space</a>
is not rendered, as if it were <a class=css data-link-type=maybe href=#propdef-display title=display>display:none</a>.
<p>
A <a href=#grid-item>grid item</a> establishes a new formatting context for its contents.
The type of this formatting context is determined by its <a class=property data-link-type=propdesc href=#propdef-display title=display>display</a> value, as usual.
The computed <a class=property data-link-type=propdesc href=#propdef-display title=display>display</a> of a <a href=#grid-item>grid item</a>
is determined by applying the table in
<a href=http://www.w3.org/TR/CSS2/visuren.html#dis-pos-flo>CSS 2.1 Chapter 9.7</a>.
However, grid items are grid-level boxes, not block-level boxes:
they participate in their container's <a href=#grid-formatting-context>grid formatting context</a>,
not in a block formatting context.
<div class=example>
<p>
Examples of grid items:
<pre><div style="display:grid">
<!-- grid item: block child -->
<div id="item1">block</div>
<!-- grid item: floated element; floating is ignored -->
<div id="item2" style="float: left;">float</div>
<!-- grid item: anonymous block box around inline content -->
anonymous item 3
<!-- grid item: inline child -->
<span>
item 4
<!-- grid items do not split around blocks -->
<div id=not-an-item>item 4</div>
item 4
</span>
</div></pre> </div>
<p>
Some values of <a class=property data-link-type=propdesc href=#propdef-display title=display>display</a> trigger the generation of anonymous boxes.
For example, a misparented <span class=css data-link-type=maybe>table-cell</span> child is fixed up
by <a href=http://www.w3.org/TR/CSS21/tables.html#anonymous-boxes>generating anonymous <span class=css data-link-type=maybe>table</span> and <span class=css data-link-type=maybe>table-row</span> elements</a> around it. <a data-biblio-type=normative data-link-type=biblio href=#css21 title=CSS21>[CSS21]</a>
This fixup must occur <em>before</em> a <a href=#grid-container>grid container</a>’s children are promoted to <a href=#grid-item>grid items</a>.
For example, given two contiguous child elements with <a class=css data-link-type=maybe href=#propdef-display title=display>display:table-cell</a>,
an anonymous table wrapper box around them becomes the <a href=#grid-item>grid item</a>.
<p class=note>
Future display types may generate anonymous containers (e.g. ruby) or otherwise mangle the box tree (e.g. run-ins).
It is intended that grid item determination run after these operations.
<h3 data-level=4.1 id=position-grid><span class=secno>4.1 </span><span class=content>
Non-children Grid Items</span><a class=section-link href=#position-grid>§</a></h3>
<p class=issue>
This is a proposal to create the ability to have descendants of a grid item participate in a grid layout,
similar to the behavior defined by the Template Layout module.
<p>
A descendant of the grid can be pulled out of flow and participate directly in the grid
by assigning it <a class=css data-link-type=maybe href=http://dev.w3.org/csswg/css-position-3/#position title=position>position: grid</a>.
An element with <a class=css data-link-type=maybe href=http://dev.w3.org/csswg/css-position-3/#position title=position>position: grid</a> is pulled out of flow and participates as a grid item
belonging to the first ancestor with <a class=css data-link-type=maybe href=#propdef-display title=display>display: grid</a>.
If the element is positioned using named lines or slots,
it belongs to the first ancestor with <a class=css data-link-type=maybe href=#propdef-display title=display>display: grid</a> that has all of the corresponding named lines/slots.
If no such ancestor exists, the item remains in flow.
<p class=issue>
Alternatively, the item can just go into the first grid,
and missing names are treated as <a data-link-for="<grid-line>" data-link-type=value href=#grid-placement-auto>auto</a>.
<h3 data-level=4.2 id=abspos-items><span class=secno>4.2 </span><span class=content>
Absolutely-positioned Grid Children</span><a class=section-link href=#abspos-items>§</a></h3>
<p>
An absolutely-positioned child element of a <a href=#grid-container>grid container</a> does not participate directly in grid layout.
Its static position is ???
<p class=issue>
The static position is affected by the alignment properties,
as if it was a 0x0 thing floating around in the <a>containing block</a>.
(Defaults to the start/start corner, since <span class=css data-link-type=maybe>stretch</span> can't do anything to it.)
<p>
If an absolutely positioned element's <a>containing block</a>
is generated by a <a href=#grid-container>grid container</a>,
the <a href=#grid-placement-properties>grid-placement properties</a> can be used to constrain it to a particular <a href=#grid-area>grid area</a>,
similar to how they affect regular <a href=#grid-item>grid items</a>.
In this case, an <a data-link-for="<grid-line>" data-link-type=value href=#grid-placement-auto>auto</a> value for a <a href=#grid-placement-properties>grid-placement property</a> indicates the corresponding padding edge of the <a href=#grid-container>grid container</a>.
<p class=note>
Absolute positioning can allow an element to “skip past” intervening grid containers,
and resolve its grid-placement properties against a grid container
other than its closest ancestor.
68E3
However, as in other forms of CSS layout,
elements that are absolutely-positioned to a <a href=#grid-container>grid container</a>
do not take up space or otherwise participate in the layout of the grid.
<h3 data-level=4.3 id=visibility-collapse><span class=secno>4.3 </span><span class=content>
Collapsed Grid Items: the <a class=property data-link-type=propdesc href=http://www.w3.org/TR/CSS21/visufx.html#propdef-visibility title=visibility>visibility</a> property</span><a class=section-link href=#visibility-collapse>§</a></h3>
<!--
<p>
Specifying <span data-link-type="maybe" class="css">visibility: collapse</span> on a <a>grid item</a> causes it to become a <dfn export title="collapsed grid item|collapsed">collapsed grid item</dfn>.
This has the same effect as <span data-link-type="maybe" class="css">visibility: hidden</span>,
except that if all the <a>grid items</a> spanning a track are <a>collapsed</a>,
the track's intrinsic size becomes zero.
-->
<p class=issue>
We want the ability to collapse grid tracks (similar to collapsing flex items or table rows/columns), but we're not sure exactly how to do it.
Ideas welcome, please post them to the list.
<h3 data-level=4.4 id=order-property><span class=secno>4.4 </span><span class=content>
Reordered Grid Items: the <a class=property data-link-type=propdesc href=http://dev.w3.org/csswg/css-flexbox-1/#order title=order>order</a> property</span><a class=section-link href=#order-property>§</a></h3>
<p>
The <a class=property data-link-type=propdesc href=http://dev.w3.org/csswg/css-flexbox-1/#order title=order>order</a> property also applies to <a href=#grid-item>grid items</a>.
It affects their <a href=#grid-auto-flow-property>auto-placement</a> and <a href=#z-order>painting order</a>.
<h2 data-level=5 id=grid-definition><span class=secno>5 </span><span class=content>
The Explicit Grid</span><a class=section-link href=#grid-definition>§</a></h2>
<p>
The three properties <a class=property data-link-type=propdesc href=#propdef-grid-template-rows title=grid-template-rows>grid-template-rows</a>, <a class=property data-link-type=propdesc href=#propdef-grid-template-columns title=grid-template-columns>grid-template-columns</a>, and <a class=property data-link-type=propdesc href=#propdef-grid-template-areas title=grid-template-areas>grid-template-areas</a>
together define the <dfn data-dfn-type=dfn data-export="" id=explicit-grid>explicit grid</dfn> of a <a href=#grid-container>grid container</a>.
The <a class=property data-link-type=propdesc href=#propdef-grid-template title=grid-template>grid-template</a> property is a shorthand that sets all three at the same time.
The final grid may end up larger due to <a href=#grid-item>grid items</a> placed outside the <a href=#explicit-grid>explicit grid</a>;
in this case, any implicit tracks are sized by the <a class=property data-link-type=propdesc href=#propdef-grid-auto-rows title=grid-auto-rows>grid-auto-rows</a> and <a class=property data-link-type=propdesc href=#propdef-grid-auto-columns title=grid-auto-columns>grid-auto-columns</a> properties.
<p>
The size of the <a href=#explicit-grid>explicit grid</a> is determined by the larger of
the number of rows/columns defined by <a class=property data-link-type=propdesc href=#propdef-grid-template-areas title=grid-template-areas>grid-template-areas</a>
and the number of rows/columns sized by <a class=property data-link-type=propdesc href=#propdef-grid-template-rows title=grid-template-rows>grid-template-rows</a>/<a class=property data-link-type=propdesc href=#propdef-grid-template-columns title=grid-template-columns>grid-template-columns</a>.
Any rows/columns defined by <a class=property data-link-type=propdesc href=#propdef-grid-template-areas title=grid-template-areas>grid-template-areas</a> but not sized by <a class=property data-link-type=propdesc href=#propdef-grid-template-rows title=grid-template-rows>grid-template-rows</a>/<a class=property data-link-type=propdesc href=#propdef-grid-template-columns title=grid-template-columns>grid-template-columns</a>
take their size from the <a class=property data-link-type=propdesc href=#propdef-grid-auto-rows title=grid-auto-rows>grid-auto-rows</a>/<a class=property data-link-type=propdesc href=#propdef-grid-auto-columns title=grid-auto-columns>grid-auto-columns</a> properties.
<p>
Numeric indexes in the <a href=#grid-placement-properties>grid-placement properties</a>
count from the edges of the <a href=#explicit-grid>explicit grid</a>,
starting from 1.
Positive indexes count from the before/start side,
while negative indexes count from the after/end side.
<h3 data-level=5.1 id=track-sizing><span class=secno>5.1 </span><span class=content>
Track Sizing: the <a class=property data-link-type=propdesc href=#propdef-grid-template-rows title=grid-template-rows>grid-template-rows</a> and <a class=property data-link-type=propdesc href=#propdef-grid-template-columns title=grid-template-columns>grid-template-columns</a> properties</span><a class=section-link href=#track-sizing>§</a></h3>
<table class=propdef><tr><th>Name:<td><dfn data-dfn-type=property data-export="" id=propdef-grid-template-columns>grid-template-columns</dfn>, <dfn data-dfn-type=property data-export="" id=propdef-grid-template-rows>grid-template-rows</dfn><tr><th>Value:<td>none | <a class=production data-link-type=type href=#typedef-track-list><track-list></a> | subgrid <a class=production data-link-type=type href=#typedef-line-names><line-names></a>*<tr><th>Initial:<td>none<tr><th>Applies to:<td><a href=#grid-container>grid containers</a><tr><th>Inherited:<td>no<tr><th>Percentages:<td>n/a<tr><th>Media:<td>visual<tr><th>Computed value:<td>As specified, except for <a data-link-for=grid-template-columns data-link-type=value href=#valuedef-auto>auto</a> (see prose)</table>
<p>
These properties specify,
as a space-separated <dfn data-dfn-type=dfn data-export="" id=track-list>track list</dfn>,
the line names and track <a href=#sizing-function>sizing functions</a> of the <a href=#grid>grid</a>.
Each <dfn data-dfn-type=dfn data-export="" id=sizing-function>sizing function</dfn> can be specified as a length,
a percentage of the <a href=#grid-container>grid container</a>’s size,
a measurement of the contents occupying the column or row,
or a fraction of the free space in the grid.
It can also be specified as a range using the <a class=css data-link-type=maybe href=#valuedef-minmaxmin-max>minmax()</a> notation,
which can combine any of the previously mentioned mechanisms to define a min and max size for the column or row.
<p>
The <a class=property data-link-type=propdesc href=#propdef-grid-template-columns title=grid-template-columns>grid-template-columns</a> property specifies the <a href=#track-list>track list</a> for the grid's columns,
while <a class=property data-link-type=propdesc href=#propdef-grid-template-rows title=grid-template-rows>grid-template-rows</a> specifies the <a href=#track-list>track list</a> for the grid's rows.
The syntax of a <a href=#track-list>track list</a> is:
<pre> <dfn data-dfn-type=type data-export="" id=typedef-track-list><track-list></dfn> = [ <a class=production data-link-type=type href=#typedef-line-names><line-names></a>? [ <a class=production data-link-type=type href=#typedef-track-size><track-size></a> | <a class=production data-link-type=function href=#funcdef-repeat title=repeat()><repeat()></a> ] ]+ <a class=production data-link-type=type href=#typedef-line-names><line-names></a>?
<dfn data-dfn-type=type data-export="" id=typedef-track-size><track-size></dfn> = minmax( <a class=production data-link-type=type href=#typedef-track-breadth><track-breadth></a> , <a class=production data-link-type=type href=#typedef-track-breadth><track-breadth></a> ) | auto | <a class=production data-link-type=type href=#typedef-track-breadth><track-breadth></a>
<dfn data-dfn-type=type data-export="" id=typedef-track-breadth><track-breadth></dfn> = <a class=production data-link-type=type href=http://dev.w3.org/csswg/css-values-3/#length-value><length></a> | <a class=production data-link-type=type href=http://dev.w3.org/csswg/css-values-3/#percentage-value><percentage></a> | <a class=production data-link-type=type href=#typedef-flex><flex></a> | min-content | max-content
<dfn data-dfn-type=type data-export="" id=typedef-line-names><line-names></dfn> = ( <a class=production data-link-type=type href=http://dev.w3.org/csswg/css-grid-1/#grid-placement-slot><ident></a>* )
</pre>
<p>Where:
<dl data-dfn-for="grid-template-columns grid-template-rows" data-dfn-type=value>
<dt><dfn data-dfn-for="grid-template-columns grid-template-rows" data-dfn-type=value data-export="" id=valuedef-length><a class=production data-link-type=type href=http://dev.w3.org/csswg/css-values-3/#length-value><length></a></dfn>
<dd>
A non-negative length, as defined by CSS3 Values. <a data-biblio-type=normative data-link-type=biblio href=#css3val title=CSS3VAL>[CSS3VAL]</a>
<dt><dfn data-dfn-for="grid-template-columns grid-template-rows" data-dfn-type=value data-export="" id=valuedef-percentage><a class=production data-link-type=type href=http://dev.w3.org/csswg/css-values-3/#percentage-value><percentage></a></dfn>
<dd>
A non-negative percentage, as defined by CSS3 Values. <a data-biblio-type=normative data-link-type=biblio href=#css3val title=CSS3VAL>[CSS3VAL]</a>
<a class=production data-link-type=type href=http://dev.w3.org/csswg/css-values-3/#percentage-value><percentage></a> values are relative to the measure (logical width) of the <a href=#grid-container>grid container</a> in column <a href=#grid-track>grid tracks</a>,
and the extent (logical height) of the <a href=#grid-container>grid container</a> in row <a href=#grid-track>grid tracks</a>.
If the measure or extent of the <a href=#grid-container>grid container</a> is an <a href=http://www.w3.org/TR/css3-sizing/#indefinite-size>indefinite size</a>,
<a class=production data-link-type=type href=http://dev.w3.org/csswg/css-values-3/#percentage-value><percentage></a> values relative to that size are treated as <a data-link-for=width data-link-type=value>auto</a>.
<dt><dfn data-dfn-for="grid-template-columns grid-template-rows" data-dfn-type=value data-export="" id=valuedef-flex><a class=production data-link-type=type href=#typedef-flex><flex></a></dfn>
<dd>
A non-negative dimension with the unit "fr".
Each <a class=production data-link-type=type href=#typedef-flex><flex></a> value takes a share of the remaining space in proportion to its value.
See <a href=#fr-unit>Flexible Lengths</a> for more details.
<dt><dfn data-dfn-for="grid-template-columns grid-template-rows" data-dfn-type=value data-export="" id=valuedef-max-content>max-content</dfn>
<dd>
Represents the largest <a href=http://www.w3.org/TR/css3-sizing/#max-size-contribution>max size contribution</a>
of the <a href=#grid-item>grid items</a> occupying the <a href=#grid-track>grid track</a>.
<dt><dfn data-dfn-for="grid-template-columns grid-template-rows" data-dfn-type=value data-export="" id=valuedef-min-content>min-content</dfn>
<dd>
Represents the largest <a href=http://www.w3.org/TR/css3-sizing/#min-size-contribution>min size contribution</a>
of the <a href=#grid-item>grid items</a> occupying the <a href=#grid-track>grid track</a>.
<dt><dfn data-dfn-for="grid-template-columns grid-template-rows" data-dfn-type=value data-export="" id=valuedef-minmaxmin-max title=minmax()>minmax(min, max)</dfn>
<dd>
Defines a size range
greater than or equal to <var>min</var>
and less than or equal to <var>max</var>.
If <var>max</var> < <var>min</var>,
then <var>max</var> is ignored and <span class=css data-link-type=maybe>minmax(min,max)</span> is treated as <var>min</var>.
<dt><dfn data-dfn-for="grid-template-columns grid-template-rows" data-dfn-type=value data-export="" id=valuedef-auto>auto</dfn>
<dd>
Computes to <span class=css data-link-type=maybe>minmax(min-content, max-content)</span>.
</dl>
<p>
The <dfn data-dfn-for="grid-template-rows grid-template-columns" data-dfn-type=value data-export="" id=valuedef-none0>none</dfn> value indicates that there is no <a href=#explicit-grid>explicit grid</a>;
any rows/columns will be implicitly generated,
and their size will be determined by the <a class=property data-link-type=propdesc href=#propdef-grid-auto-rows title=grid-auto-rows>grid-auto-rows</a> and <a class=property data-link-type=propdesc href=#propdef-grid-auto-columns title=grid-auto-columns>grid-auto-columns</a> properties.
<p>
The <dfn data-dfn-for="grid-template-rows grid-template-columns" data-dfn-type=value data-export="" id=valuedef-subgrid>subgrid</dfn> value indicates that the grid will align to its parent grid in that axis.
Rather than specifying the sizes of rows/columns explicitly,
they'll be taken from the parent grid's definition.
If the <a href=#grid-container>grid container</a> is not a <a href=#grid-item>grid item</a>,
this value computes to <a data-link-for=grid-template-rows data-link-type=value href=#valuedef-none0>none</a>.
See the <a href=#subgrids>Subgrids</a> section for more detail.
<div class=example>
<p>
Given the following <a class=property data-link-type=propdesc href=#propdef-grid-template-columns title=grid-template-columns>grid-template-columns</a> declaration:
<pre>grid-template-columns: 100px 1fr max-content minmax(min-content, 1fr);</pre>
<p>
Five grid lines are created:
<ol>
<li>
At the start edge of the <a href=#grid-container>grid container</a>.
<li>
100px from the start edge of the <a href=#grid-container>grid container</a>.
<li>
A distance from the previous line equal to half the <a href=#free-space>free space</a>
(the width of the <a href=#grid-container>grid container</a>, minus the width of the non-flexible <a href=#grid-track>grid tracks</a>).
<li>
A distance from the previous line equal to the maximum size of any <a href=#grid-item>grid items</a>
belonging to the column between these two lines.
<li>
A distance from the previous line at least as large as the largest minimum size of any <a href=#grid-item>grid items</a>
belonging to the column between these two lines,
but no larger than the other half of the <a href=#free-space>free space</a>.
</ol>
<p>
If the non-flexible sizes
(<span class=css data-link-type=maybe>100px</span>, <a class=css data-link-type=maybe href=#valuedef-max-content>max-content</a>, and <a class=css data-link-type=maybe href=#valuedef-min-content>min-content</a>)
sum to larger than the <a href=#grid-container>grid container</a>’s width,
the final <a href=#grid-line>grid line</a> will be a distance equal to their sum away from the start edge of the <a href=#grid-container>grid container</a>
(the <span class=css data-link-type=maybe>1fr</span> sizes both resolve to <span class=css data-link-type=maybe>0</span>).
If the sum is less than the <a href=#grid-container>grid container</a>’s width,
the final <a href=#grid-line>grid line</a> will be exactly at the end edge of the <a href=#grid-container>grid container</a>.
This is true in general whenever there's at least one <a class=production data-link-type=type href=#typedef-flex><flex></a> value among the <a href=#grid-track>grid track</a> sizes.
</div>
<div class=example>
<p>
Additional examples of valid <a href=#grid-track>grid track</a> definitions:
<pre>/* examples of valid track definitions */
grid-template-rows: 1fr minmax(min-content, 1fr);
grid-template-rows: 10px repeat(2, 1fr auto minmax(30%, 1fr));
grid-template-rows: calc(4em - 5px)</pre> </div>
<p class=issue>
We should have some way of defining "gutter" columns/rows,
where content can never go
(unless it's spanning across two tracks).
Otherwise, auto-flow is completely broken when you manually add gutters,
and it's just much less convenient to add them manually.
<a href=http://lists.w3.org/Archives/Public/www-style/2013May/0057.html>Lea's email on the subject.</a>
<a href=http://lists.w3.org/Archives/Public/www-style/2013May/0077.html>Our proposal.</a>
<h4 data-level=5.1.1 id=named-lines><span class=secno>5.1.1 </span><span class=content>
Named Grid Lines: the <span class=css data-link-type=maybe>(<a class=production data-link-type=type href=http://dev.w3.org/csswg/css-grid-1/#grid-placement-slot><ident></a>*)</span> syntax</span><a class=section-link href=#named-lines>§</a></h4>
<p>
While <a href=#grid-line>grid lines</a> can always be referred to by their numerical index,
<dfn data-dfn-type=dfn data-export="" id=named-lines0 title="named line">named lines</dfn>
can make the <a href=#grid-placement-properties>grid-placement properties</a> easier to understand and maintain.
Lines can be explicitly named in the <a class=property data-link-type=propdesc href=#propdef-grid-template-rows title=grid-template-rows>grid-template-rows</a> and <a class=property data-link-type=propdesc href=#propdef-grid-template-columns title=grid-template-columns>grid-template-columns</a> properties,
or <a href=#implicit-named-lines>implicitly named</a> by creating <a href=#named-grid-areas>named grid areas</a> with the <a class=property data-link-type=propdesc href=#propdef-grid-template-areas title=grid-template-areas>grid-template-areas</a> property.
<div class=example>
<p>
For example,
the following code gives meaningful names to all of the lines in the grid.
Note that some of the lines have multiple names.
<pre><style>
#grid {
display: grid;
grid-template-columns: (first nav) 150px (main) 1fr (last);
grid-template-rows: (first header) 50px (main) 1fr (footer) 50px (last);
}
</style></pre>
<div class=figure>
<amg alt="Image: Named Grid Lines." class=figure src=images/grid-named-lines.png>
<p class=caption>Named Grid Lines.
</amg></div>
</div>
<p class=issue>