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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang=en>
<head
profile="http://microformats.org/profile/hcard http://microformats.org/wiki/rel-license">
<title>CSS Grid Template Layout Module</title>
<meta content="text/html; charset=utf-8" http-equiv=content-type>
<link href="../default.css" rel=stylesheet type="text/css">
<style type="text/css">
/* Just in case an incorrect max-width occurs in default.css */
body {max-width: none !important}
.prod { font-family: inherit; font-size: inherit }
pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
code { font-size: inherit; }
/* Content that could be moved to level 4 */
.level4 {color: gray; clear: both}
.level4 h2, .level4 h3, .level4 h4 {color: inherit}
p.level4:before, div.level4:before, li.level4:before {
content: "LEVEL\A 4"; background: #BBB; color: white; white-space: pre;
text-align: center; float: left; margin: 0 0.3em 0.1em 0; min-width: 0;
border-radius: 100%; line-height: 1; font-size: small;
padding: 1.1em 0.4em 0.6em 0.4em}
/* Content to be moved to css3-grid */
/*
.grid h2, .grid h3, .grid h4 {color: inherit}
p.grid:before, div.grid:before, li.grid:before {
content: "BASIC\A GRID"; background: #BB0; color: white; white-space: pre;
text-align: center; float: left; margin: 0 0.3em 0.1em 0; min-width: 0;
border-radius: 100%; line-height: 1; font-size: small;
padding: 1.1em 0.4em 0.6em 0.4em}
ins.grid {font-weight: bold; background: none; color: inherit;
text-decoration: none; border-bottom: solid thin #BB8}
*/
.example .visible {border: thin dotted silver}
</style>
<link href=with.css rel=stylesheet title="With basic grid and level 4">
<link href=without-grid.css rel="alternate stylesheet"
title="Without basic grid">
<link href=without-grid-4.css rel="alternate stylesheet"
title="Without basic grid and level 4">
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet>
<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>CSS Grid Template Layout Module</h1>
<!--=================================================================-->
<h2 class="no-num no-toc" id=longstatus-date-3-august-2004>Editor's Draft
10 August 2012</h2>
<dl>
<dt>This version:
<dd><a
href="http://www.w3.org/TR/2012/ED-css3-layout-20120810/">http://www.w3.org/TR/2012/ED-css3-layout-20120810/</a>
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css3-layout/">http://www.w3.org/TR/css3-layout/</a>
<dt>Previous version:
<dd><a
href="http://www.w3.org/TR/2011/WD-css3-layout-20111129/">http://www.w3.org/TR/2011/WD-css3-layout-20111129/</a>
<dt>Editors:
<dd class=vcard><span class=fn>Bert Bos</span> (<span
class=org>W3C</span>) <a class=email href="mailto:bert@w3.org"
rel=author>bert@w3.org</a>
<dd class=vcard><span class=fn>César Acebal</span> (<span
class=org>University of Oviedo</span>)
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2012 <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>), 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>
<div class=sidefigure>
<p><img alt="Image: four elements move to four slots in a template"
longdesc=diagram.desc src=diagram.png>
<p class=caption>Above: a typical Web page. Below: the underlying grid
template.
</div>
<p>CSS is a simple, declarative language for creating style sheets that
specify the rendering of HTML and other structured documents. This module
defines a typographic grid for CSS. <del class=grid>It has features to set
up a grid template, to flow content into it, and to position overlapping
elements on a grid.</del> <ins class=grid>It uses the grid defined in <a
href="#CSS3GRID" rel=biblioentry>[CSS3GRID]<!--{{!CSS3GRID}}--></a> to
build a template into which an element's content can flow.</ins>
<p><del class=grid>The ‘<a href="#grid0"><code
class=property>grid</code></a>’ property sets up a matrix of rows and
columns and designates empty areas and areas for content (called
“slots”).</del> The ‘<a href="#flow0"><code
class=property>flow</code></a>’ property specifies into which slot an
element flows. A grid template is like a table in that the various slots
are aligned in rows and columns and can automatically adapt to each
other's size, and it is like absolute positioning in that elements can be
put in arbitrary slots so that the visual order becomes independent of the
document order.
<p>The <a href="#slot-pseudo-element.">‘<code
class=css>::slot()</code>’ pseudo-element</a> allows to style the slots
(backgrounds, borders, etc.)
<p class=grid>Use ‘<a href="#grid-area"><code
class=property>grid-area</code></a>’ instead of ‘<a
href="#flow0"><code class=property>flow</code></a>’ to put multiple
elements on top of one another in the same slot.
<p class=level4>Grid templates can also be associated with pages in paged
media, to create page templates.
<p class=level4>Slots can form “chains” to create non-rectangular
regions. A chain of slots is like a series of pages or columns: content is
distributed over the slots by breaking it at possible break points (see
the ‘<code class=css>break-*</code>’ properties from <a
href="#CSS3-BREAK" rel=biblioentry>[CSS3-BREAK]<!--{{CSS3-BREAK}}--></a>).
<p class=level4>The <a href="#region-based">‘<code
class=css>::flow()</code>’ pseudo-element</a> allows to select (parts
of) elements based on whether they fall in a certain slot or not, and thus
style content differently in different slots (region-based styling).
<!--=================================================================-->
<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-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-layout” in the subject, preferably like this:
“[<!---->css3-layout<!---->] <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>.</p>
<!--end-status-->
<p>This draft combines ideas from earlier drafts on Template Layout, Grid
Positioning <a href="#CSS3GRID"
rel=biblioentry>[CSS3GRID]<!--{{CSS3GRID}}--></a> and Grid Layout <a
href="#CSS3-GRID-LAYOUT"
rel=biblioentry>[CSS3-GRID-LAYOUT]<!--{{CSS3-GRID-LAYOUT}}--></a>.
<p>The module is expected to be split into two or three smaller modules or
some parts may be split off to form a level-4 module. Those parts are
marked <span class=level4>like this</span> or
<p class=level4 style="overflow: auto">like this.
<p>The section on <a href="#cr-exit-criteria">“CR exit criteria”</a>
lists some conditions for this specification to become a W3C
Recommendation.
<p>Issues on this draft are mentioned in the text itself and/or in the
on-line Tracker under <a
href="http://www.w3.org/Style/CSS/Tracker/products/15">“Details on
Product CSS3 Template Layout.”</a>
<!--=================================================================-->
<h2 class="no-num no-toc" id=contents>Table of contents</h2>
<!--begin-toc-->
<ul class=toc>
<li><a href="#introduction"><span class=secno>1. </span>Introduction</a>
<ul class=toc>
<li><a href="#summary-and-use-cases"><span class=secno>1.1.
</span>Summary and use cases</a>
<li><a href="#dependencies"><span class=secno>1.2. </span>Dependencies
on other modules</a>
<li><a href="#values"><span class=secno>1.3. </span>Values</a>
<li><a href="#accessibility"><span class=secno>1.4. </span>A note about
accessibility</a>
</ul>
<li><a href="#declaring-templates"><span class=secno>2. </span>Declaring
templates</a>
<ul class=toc>
<li class=grid><a href="#grid-template"><span class=secno>2.1.
</span>Declaring a template: ‘<code
class=property>grid-template</code>’</a>
<li class=grid><a href="#grid-column-sizes"><span class=secno>2.2.
</span>Specifying the widths of columns: ‘<code
class=property>grid-columns</code>’</a>
<li class=grid><a href="#grid-row-sizes"><span class=secno>2.3.
</span>Specifying the height of rows: ‘<code
class=property>grid-rows</code>’</a>
<li class=grid><a href="#grid-shorthand"><span class=secno>2.4.
</span>The ‘<code class=property>grid</code>’ shorthand
property</a>
<li class=grid><a href="#default"><span class=secno>2.5. </span>Default
slots</a>
<li class=grid><a href="#slot-sizes"><span class=secno>2.6.
</span>Calculating the size of the grid</a>
</ul>
<li><a href="#positioning"><span class=secno>3. </span>Putting content
into a grid element</a>
<ul class=toc>
<li><a href="#flow"><span class=secno>3.1. </span>Flowing content into
slots: ‘<code class=property>flow</code>’</a>
<li class=grid><a href="#stacking-elements-on-top-of-a-grid-grid-"><span
class=secno>3.2. </span>Stacking elements on top of a grid: ‘<code
class=property>grid-area</code>’</a>
</ul>
<li><a href="#slot-pseudo"><span class=secno>4. </span>Styling slots: the
‘<code class=css>::slot()</code>’ pseudo-element</a>
<li class=level4><a href="#region-based"><span class=secno>5.
</span>Styling the contents of slots: ‘<code
class=css>::flow()</code>’</a>
<li><a href="#rendering-of-grid-elements"><span class=secno>6.
</span>Rendering of grid elements</a>
<ul class=toc>
<li><a href="#vertical-alignment"><span class=secno>6.1. </span>Vertical
alignment of the contents of slots</a>
<li><a href="#paged"><span class=secno>6.2. </span>Breaking grid
elements across pages or columns</a>
<li class=grid><a href="#stacking-order"><span class=secno>6.3.
</span>Stacking order</a>
<li><a href="#floating-elements-inside-templates"><span class=secno>6.4.
</span>Floating elements inside templates</a>
</ul>
<li class=level4><a href="#page-templates"><span class=secno>7.
</span>Page-based grid templates</a>
<li class=level4><a href="#chains"><span class=secno>8. </span>Chaining
slots: the ‘<code class=property>chains</code>’ property</a>
<li><a href="#cr-exit-criteria"><span class=secno>9. </span>CR exit
criteria</a>
<li><a href="#history"><span class=secno>10. </span>History</a>
<ul class=toc>
<li><a href="#developing-a-model-of-declaring-using-st"><span
class=secno>10.1. </span>Developing a model of declaring, using,
styling and resizing grids</a>
<li><a href="#syntax-features-and-levels"><span class=secno>10.2.
</span>Syntax, features and levels</a>
<ul class=toc>
<li><a href="#named-vs-numbered-slots"><span class=secno>10.2.1.
</span>Named vs numbered slots</a>
<li><a href="#single-letter-names-vs-identifiers"><span
class=secno>10.2.2. </span>Single letter names vs identifiers</a>
<li><a href="#display"><span class=secno>10.2.3. </span>Extend
‘<code class=property>display</code>’ or add a grid property</a>
<li><a href="#combining-columns-and-grids"><span class=secno>10.2.4.
</span>Combining columns and grids</a>
<li><a href="#shorthand-vs-single-property"><span class=secno>10.2.5.
</span>Shorthand vs single property</a>
<li><a href="#the-number-of-rows-and-columns"><span
class=secno>10.2.6. </span>The number of rows and columns</a>
<li><a href="#need-fr"><span class=secno>10.2.7. </span>‘<code
class=css>*</code>’ vs ‘<code class=css>fr</code>’</a>
<li><a href="#auto-add"><span class=secno>10.2.8. </span>Automatically
add rows and columns</a>
<li><a href="#rectangular-slots-vs-non-rectangular-slo"><span
class=secno>10.2.9. </span>Rectangular slots vs non-rectangular
slots</a>
<li><a href="#chained"><span class=secno>10.2.10. </span>Chained
slots</a>
<li><a href="#page-grid"><span class=secno>10.2.11. </span>Page
grids</a>
<li><a href="#style-the-slots-pseudo-elements"><span
class=secno>10.2.12. </span>Style the slots (pseudo-elements)</a>
<li><a href="#style-the-contents-of-slots-region-based"><span
class=secno>10.2.13. </span>Style the contents of slots (region-based
styling)</a>
<li><a href="#orient-the-grid-with-writing-mode-vs-ori"><span
class=secno>10.2.14. </span>Orient the grid with writing mode vs
orient the slots</a>
<li><a href="#indicating-the-default-slot-vs-"><span
class=secno>10.2.15. </span>Indicating the default slot (‘<code
class=css>*</code>’ vs ‘<code class=css>@</code>’)</a>
<li><a href="#abspos"><span class=secno>10.2.16. </span>Flowing vs
absolutely positioning content in a grid</a>
<li><a href="#use-the-pseudo-class-to-create-additiona"><span
class=secno>10.2.17. </span>Use the pseudo-class to create additional
slots</a>
<li><a href="#names-for-edges"><span class=secno>10.2.18. </span>Names
for edges</a>
<li><a href="#position-from-the-right-and-bottom"><span
class=secno>10.2.19. </span>Position from the right and bottom</a>
<li><a href="#syntax-features-to-shorten-long-grid-spe"><span
class=secno>10.2.20. </span>Syntax features to shorten long grid
specifications</a>
<li><a href="#fit-content-vs-auto-vshellip"><span class=secno>10.2.21.
</span>‘<code class=css>fit-content</code>’ vs ‘<code
class=css>auto</code>’ vs…</a>
<li><a href="#vert-align"><span class=secno>10.2.22. </span>Vertical
alignment inside slots</a>
<li><a href="#horizontal-alignment-inside-slots"><span
class=secno>10.2.23. </span>Horizontal alignment inside slots</a>
<li><a href="#auto-margins-on-slots"><span class=secno>10.2.24.
</span>Auto margins on slots</a>
<li><a href="#page-floats"><span class=secno>10.2.25. </span>Page
floats</a>
<li><a href="#break-properties"><span class=secno>10.2.26.
</span>Break-* properties</a>
<li><a href="#next-same"><span class=secno>10.2.27. </span>Automatic
placement of elements</a>
</ul>
</ul>
<li><a href="#changes"><span class=secno>11. </span>Changes</a>
<li class=no-num><a href="#acknowledgments">Acknowledgments</a>
<li class=no-num><a href="#references">References</a>
<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=introduction><span class=secno>1. </span>Introduction</h2>
<p><em>(This section is not normative.)</em>
<h3 id=summary-and-use-cases><span class=secno>1.1. </span>Summary and use
cases</h3>
<div class=sidefigure>
<p><img alt="Image: four elements move to four slots in a template"
longdesc=diagram.desc src=diagram.png>
<p class=caption>Above: a typical Web page. Below: the underlying grid
template. It has four slots, a, b, c and d and the grid template is
defined by ‘<code class=css>grid: "a a a a a a a" "b c c c c d
d"</code>’.
</div>
<p class=mtb>The styling of a Web page, a form or a graphical user
interface can roughly be divided into two parts: (1) defining the overall
“grid” of the page or window and (2) specifying the fonts, indents,
colors, etc., of the text and other objects. The two are not completely
separate, of course, because indenting or coloring a text influences the
perceived grid as well. Nevertheless, when one separates the parts of a
style that should change when the window gets bigger from the parts that
stay the same, one often finds that the grid changes (room for a sidebar,
extra navigation bar, big margins, larger images…), while fonts, colors,
indents, numbering styles, and many other things don't have to change,
until the size of the window becomes extreme.
<p>The properties in this specification associate a layout grid with an
element. Rather than rendering all descendants of an element in a single
flow, they give an element multiple flows, called <a
href="#slot">slots,</a> placed on an invisible grid by means of a
<span>grid template.</span> The descendants are given a ‘<a
href="#flow0"><code class=property>flow</code></a>’ property to
designate the slot into which they flow.
<p>Because layouts on the Web have to adapt to different window and paper
sizes, the rows and columns of the grid can be made fixed or flexible in
size.
<p class=note>In some typographical traditions, the slots are called
“<span class=index id=fields
title="field (of a typographical grid)">fields</span>.” Traditionally,
also, all columns have the same width, called the “<span class=index
id=module title="module (of a typographical grid)">module</span>” or
“<span class=index id=unit
title="unit (of a typographical grid)">unit</span>,” so that the width
of a field is always a multiple of the module. This specification does not
use those terms, because equal-width columns is merely the default in CSS,
which means the grid does not necessarily have a “module.”
<p>The typical use cases for these properties include:
<ul>
<li>
<p>Complex Web pages, with multiple navigation bars in fixed positions,
areas for advertisements, etc.
<li>
<p>Complex forms, where the alignment of labels and form fields may be
easier with the properties of this module than with the properties for
tables and margins.
<li>
<p>GUIs, where buttons, toolbars, labels, icons, etc., are aligned in
complex ways and have to stay aligned (and not wrap, for example) when
the window is resized.
<li class=level4>
<p>Paged displays (e.g., printed media) where each page is divided in
fixed areas for different kinds of content.
<li class=level4>
<p>Complex pages with multiple regions, where the style of the text does
not only depend on the type of element it comes from, but also on the
region it is displayed in.
</ul>
<p>Once a grid template has been defined, it can also be used to position
elements without adding them to a flow, typically for the purpose of
making them overlap (somewhat similar to absolute positioning). For those
elements, ‘<a href="#grid-area"><code
class=property>grid-area</code></a>’, instead of ‘<a
href="#flow0"><code class=property>flow</code></a>’, specifies the
position; and ‘<a href="#z-index"><code
class=property>z-index</code></a>’ determines the stacking order. <ins
class=grid>This feature is defined in <a href="#CSS3-GRID-LAYOUT"
rel=biblioentry>[CSS3-GRID-LAYOUT]<!--{{!CSS3-GRID-LAYOUT}}--></a>.</ins>
<p>Template-based positioning makes many traditional uses of absolute
positioning unnecessary. Like absolute positioning, grid templates are
especially useful for aligning elements that don't have simple
relationships in the source (parent-child, ancestor-descendant, immediate
sibling). But in contrast to absolute positioning, the elements are not
positioned with the help of horizontal and vertical coordinates, but by
flowing them into a template that is very much like a table: The size and
alignment of elements are governed implicitly by the rows and columns of
the template, and can automatically adapt to the overall size of the
element and to the content in each row and column.
<div class=example>
<p>In this example, the four children of an element are assigned to four
slots (called a, b, c and d) in a 2×2 template. (All mark-up examples in
this specification are HTML fragments, unless otherwise stated.)
<div class=sidefigure>
<p><img alt="Image: sample rendering" longdesc=aapje.desc src=aapje.png>
<p class=caption>Each element occupies one slot. In this template, all
slots have the same size.
</div>
<pre>
<style type="text/css">
dl { grid: "a b"
"c d" }
#sym1 { flow: a }
#lab1 { flow: b }
#sym2 { flow: c }
#lab2 { flow: d }
</style>
<dl>
<dt id=sym1>A
<dd id=lab1>A is een aapje
<dt id=sym2>B
<dd id=lab2>B is de bakker
</dl>
</pre>
<p><a href=ex-aapje.html>Try it out!</a> (Uses a JavaScript emulation in
browsers that do not implement grid templates natively.)
</div>
<div class=example>
<p>Templates can also help with device-independence. This example uses
Media Queries <a href="#MEDIAQ"
rel=biblioentry>[MEDIAQ]<!--{{MEDIAQ}}--></a> to change the overall
layout of a page from 3-column layout for a wide screen to a 1-column
layout for a narrow screen. It assumes the page has been marked-up with
logical sections with IDs.
<pre>
@media all
{
body { grid: "a a a"
"b c d" }
#head { flow: a }
#nav { flow: b }
#adv { flow: c }
#body { flow: d }
}
@media all and (max-width: 500px)
{
body { grid: "a"
"b"
"c" }
#head { flow: a }
#nav { flow: b }
#adv { display: none }
#body { flow: c }
}
</pre>
</div>
<div class=example>
<p>The slots in a grid do not overlap, unless with negative margins. Here
is how the <a
href="http://www.csszengarden.com/?cssfile=/026/026.css&page=0">
“zunflower” design</a> of the CSS Zen Garden could be done:
<pre>
#container {grid: "A B C"}
#container::slot(A) {box-shadow: 0.5em 0.5em 0.5em; z-index: 1}
#container::slot(B) {box-shadow: 0.5em 0.5em 0.5em; margin-left: -2em}
#intro {flow: A}
#supportingText {flow: B}
#linkList {flow: C}
</pre>
</div>
<div class=example>
<p>Template-based positioning borrows some concepts from table layout, in
particular the idea of aligning elements in rows and columns, so that
they constrain one another's size. But there are also differences. This
example shows some of them. Assume this document fragment:
<pre>
<div class=group>
<div>aa aa aa aa aa aa</div>
<div>bbb</div>
<div class=menu>ccccc</div>
</div>
</pre>
<p>We can lay it out as three columns, as the following illustrations
show. The style sheet would contain the following.
<pre>
.group {display: table}
.group > div {display: table-cell}
</pre>
<div class=figure>
<p><img alt="[Three unequal cells]" longdesc=table1.desc src=table1.png>
<p class=caption>Example of rendering with a table.
</div>
<p>We can also use a template, in which case the style sheet would contain
this:
<pre>
.group {grid: "a b c"}
.group > div {flow: a}
.group > div + div {flow: b}
.group > div + div + div {flow: c}
</pre>
<p>By default, the table is as wide as needed to fit its contents. To make
sure it is as wide as its containing block, we need to add
<pre>.group {display: table; width: 100%}</pre>
<p>That is not needed for the grid template, but, on the other hand, if we
want the template to fit its contents, we would need to say so:
<pre>.group {grid: "a b c"; width: auto}</pre>
<p>(See <a href="#CSS3BOX"
rel=biblioentry>[CSS3BOX]<!--{{!CSS3BOX}}--></a> for the definition of
the ‘<a href="#width"><code class=property>width</code></a>’
property.) The columns of the template are by default all the same size.
The columns of the table satisfy certain constraints, but the exact size
is not defined. We can make them all the same by adding a rule (see <a
href="#CSS3TBL" rel=biblioentry>[CSS3TBL]<!--{{!CSS3TBL}}--></a>):
<pre>.group {display: table; width: 100%; table-layout: fixed}</pre>
<div class=figure>
<p><img alt="[Three equal cells]" longdesc=table2.desc src=table2.png>
<p class=caption>Example of rendering with equal columns.
</div>
<p>In both styles, we can set a column to a certain size:
<pre>div.menu {width: 3em}</pre>
<p>resp.,
<pre>.group {grid: * * 3em "a b c"}</pre>
<div class=figure>
<p><img alt="[Two equal cells, third is 3em wide]" longdesc=table3.desc
src=table3.png>
<p class=caption>Example of rendering with a fixed third column and the
other two columns of equal width.
</div>
<p>If there is an unknown number of columns (children of the div.group
element), the style sheet for the table model will automatically take
them into account. The style sheet for the template model, however,
creates a template of exactly three columns and can't handle tables with
an unknown number of columns. The extra elements will be added into the
default slot (in this case the ‘<code class=css>a</code>’ slot).
<p>(However, extra columns or rows <em>will</em> be created if necessary
to absolutely position elements. See the ‘<a href="#grid-area"><code
class=property>grid-area</code></a>’ property.)
<p>In both models, elements can have borders, but only in the table model
can borders be collapsed, which makes setting borders easier in the table
model:
<pre>
.group {display: table; border-collapse: collapse}
.group > div {border: solid}
</pre>
<p>resp.,
<pre>
.group > div {border: solid; border-left: none}
.group > div:first-child {border-left: solid}
</pre>
<p>In the template model, the order of the elements is explicit, and thus
it is possible to reverse the order of the columns:
<pre>
.group > div {flow: c}
.group > div + div {flow: b}
.group > div + div + div {flow: a}
</pre>
<div class=figure>
<p><img alt="[Different contents for the cells]" longdesc=table4.desc
src=table4.png>
<p class=caption>Example of rendering with the contents of the three
columns reversed: the third element is shown in the first slot and the
first element in the third slot.
</div>
<p>In the table model, the order of the rows and columns is given by the
document source and thus can't be changed.
</div>
<div class=example>
<p>This example shows a way to move notes to the end of a section.
“Notes” in this example refers to elements in HTML with a class of
“note”. A fragment of HTML such as
<pre>
<div class=section>
<p>The balubious coster of the fifth secter<span
class=note> The sixth secter coster is a difter
manon.</span> of The Rollow Carpug mentizes a costernica.
<p>…
</div>
</pre>
<p>with this style sheet
<pre>
div.section {
grid: "*"
"F"}
.note {
flow: F;
content: counter(note) ".\A0" contents;
counter-increment: note;
font-size: smaller}
.note::before {
content: counter(note);
vertical-align: super;
font-size: larger}
</pre>
<p>results in a rendering similar to this:
<div class=figure>
<p><img
alt="Same text, with the SPAN replaced by “(1)” and its content moved to the end."
longdesc=footnotes.desc src=footnotes.png>
<p class=caption>Rendering of a text with footnotes.
</div>
<p>The “Generated content for paged media” module <a href="#CSS3GCPM"
rel=biblioentry>[CSS3GCPM]<!--{{CSS3GCPM}}--></a> is expected to define
specific features for footnotes that are both easier and more powerful
than this example.
</div>
<div class="example level4">
<p>This example shows the use of chained regions: text from region 1
continues in region 2, 3 and 4. And it shows how to use pseudo-elements
to style text in a particular region: text in region 1 is bigger than in
other regions.
<div class=figure>
<p><img alt="Image of a complex, 3-column layout"
longdesc=regions-intro-rendering.desc src=regions-intro-rendering.png>
<p class=caption>Example rendering
</div>
<p>We assume a document fragment similar to this:
<pre>
<div id=article>
<h1>Introduction</h1>
<p><img src="sunset" alt="">
<p>This is an example…
<h1>More Details</h1>
<p>This illustrates…
<p>Then, the example…
<p>Finally, this…
</div>
</pre>
<p>The style sheet makes the DIV into a template element with five
regions, called A, *, b, c and d. The regions are grouped into two
chains: region A on its own, and the chain consisting of *, b, c and d.
<pre>
#article {
grid: "A A c"
"A A c"
"* * c"
"a b c";
chains: * a b c }
</pre>
<p>The ‘<code class=css>*</code>’ is a special name. It indicates the
<a href="#default-slot."><em>default slot,</em></a> the slot where
content goes if it doesn't have an explicit ‘<a href="#flow0"><code
class=property>flow</code></a>’ property. We could have used a normal
letter and added an explicit ‘<a href="#flow0"><code
class=property>flow</code></a>’ property to the children of the DIV,
but by using * we don't have to. All children thus go into region * (and
continue in a, b and c as needed). The IMG element goes into region A. We
assume for simplicity that there is only one IMG element:
<pre>#article img { flow: A }</pre>
<p>The text in region * is bolder, larger and a different color than in
the other regions. Also, an H1 that falls into this region is rendered
differently from other H1s:
<pre>
::slot(*) {
font-weight: bold;
color: #0C3D5F;
font-size: larger }
h1::slot(*) {
color: crimson;
display: run-in }
</pre>
<p>(For brevity, the example doesn't show the style rules to set the color
and background, to make the text justified, add the left border to the
second H1, etc.)
<p>As the image shows, the text of the last paragraph isn't complete and
presumably continues somewhere else, but that part is outside the scope
of this example. In paged media, we could attach the grid template to a
page instead of an element and let the text continue on the next page; we
could also make slot c into a multi-column element so that the text forms
additional columns to the right of current image (see <a href="#CSS3GCPM"
rel=biblioentry>[CSS3GCPM]<!--{{CSS3GCPM}}--></a> for some ideas), or we
could allow a scrollbar on slot c.
</div>
<div class=example>
<p>This example shows two [three] ways to align the contents of a
fixed-height paragraph to the bottom of the box:
<dl>
<dt>Method 1
<dd>
<pre>P {height: 20em; grid: "." "*" fit-content}</pre>
<dt>Method 2
<dd>
<pre>P {height: 20em; grid: "*"}
P::slot(*) {vertical-align: bottom}</pre>
<dt>[Method 3]
<dd class=issue>
<pre>P {height: 20em; vertical-align: bottom}</pre>
</dl>
<p>However, the styles differ in case the content is taller than 20 em
and overflows: the first style has a baseline-aligned content which will
thus overflow <em>below</em> the element's box; the second example has
bottom-aligned content, which will thus overflow <em>above</em> the
element's box.
</div>
<div class=example>
<p>This example (based on a challenge by Andrew Fedoniouk) shows how a
grid template can be used to display six items in two rows of three.
Assume the following document:
<pre>
<p>
<span>...</span>
<span>...</span>
<span>...</span>
<span>...</span>
<span>...</span>
<span>...</span>
</p>
</pre>
<p>The simplest way to break this into two lines (or more) is to add a
hard line break after the third SPAN: ‘<code
class=css>span:nth-child(3)::after {content: "\A"; white-space:
pre}</code>’. That works fine, unless the SPANs are inline blocks
(‘<code class=css>span {display: inline-block}</code>’). Another way
is to float all SPANs and add a ‘<code class=property>clear</code>’
property on the fourth: ‘<code class=css>span {float: left}
span:nth-child(4) {clear: left}</code>’. But if the SPANs have
different heights or baselines, their vertical alignment will be
different than if they were on the same line.
<p>With a grid template, we can say that the P has not one, but two flows,
a and b; and then we assign the fourth and subsequent SPANs to the
“b” flow. (The others automatically go into the default, first flow.)
<pre>
p {grid: "a" "b"}
span:nth-child(n+4) {flow: b}
</pre>
<p>This almost works. There is just a subtle issue with the spaces between
the SPANs. We moved the last three SPANs to flow b, but we have no way to
move the spaces between them. They remain in the default (first) slot.
(They collapse, as there is nothing left between them, so we don't
actually see them anymore.) To get spaces between the SPANs in slot b, we
need to generate new spaces:
<pre>span:nth-child(n+4)::after {content: " "}</pre>
<p class=issue>This space handling not very intuitive. One might expect
there to be a way to say “select everything from this element onward”
or maybe a pseudo-element selector for the text between elements. Or a
new property to specify different ways to handle the anonymous text
inside a grid element. For the moment, there is no such thing.
Suggestions are welcome.
</div>
<!--=================================================================-->
<h3 id=dependencies><span class=secno>1.2. </span>Dependencies on other
modules</h3>
<p>This CSS3 module depends on the following other CSS3 modules:
<ul>
<li><cite>CSS 2.1</cite> <a href="#CSS21"
rel=biblioentry>[CSS21]<!--{{!CSS21}}--></a> – <a
href="http://www.w3.org/TR/CSS21/visuren.html#block-boxes"><dfn
id=block-container>block container</dfn></a> and property <dfn
id=content>content</dfn>.
<li><cite>CSS syntax module</cite> <a href="#CSS3SYN"
rel=biblioentry>[CSS3SYN]<!--{{!CSS3SYN}}--></a> – <dfn
id=interactive>interactive</dfn> vs <dfn
id=non-interactive>non-interactive</dfn> media.
<li><cite>CSS values and Units module</cite> <a href="#CSS3VAL"
rel=biblioentry>[CSS3VAL]<!--{{!CSS3VAL}}--></a> – <a
href="/TR/css3-values#strings"> <dfn
id=ltstringgt><var><string></var></dfn></a> and <a
href="/TR/css3-values#length-value"> <dfn
id=ltlengthgt><var><length></var></dfn></a>.
<li><cite>CSS box module</cite> <a href="#CSS3BOX"
rel=biblioentry>[CSS3BOX]<!--{{!CSS3BOX}}--></a> – properties <dfn
id=margin>margin</dfn>, <dfn id=margin-right>margin-right</dfn>, <dfn
id=margin-left>margin-left</dfn>, <dfn id=width>width</dfn>, <dfn
id=height>height</dfn>, <dfn id=float>float</dfn>, <dfn
id=display0>display</dfn> and <dfn id=overflow>overflow</dfn>
<li><cite>CSS text layout</cite> <a href="#CSS3-WRITING-MODES"
rel=biblioentry>[CSS3-WRITING-MODES]<!--{{!CSS3-WRITING-MODES}}--></a>
– defines <dfn id=block-flow-direction>block flow direction</dfn> and
the properties <dfn id=direction>direction</dfn> and <dfn
id=writing-mode>writing-mode</dfn>. The latter defines when an element
has a <dfn id=vertical-writing-mode>vertical writing mode</dfn> (text
lines are vertical) or a <dfn id=horizontal-writing-mode>horizontal
writing mode</dfn> (text lines are horizontal). For brevity, we refer to
the former as a <dfn id=vertical-element
title="vertical|vertical element">vertical element</dfn> and to the
latter as a <dfn id=horizontal-element.
title="horizontal|horizontal element">horizontal element.</dfn>
<li><cite>CSS positioning</cite> <a href="#CSS3POS"
rel=biblioentry>[CSS3POS]<!--{{!CSS3POS}}--></a> – properties <dfn
id=z-index>z-index</dfn>, <dfn id=position>position</dfn>, <dfn
id=top>top</dfn>, <dfn id=right>right</dfn>, <dfn id=bottom>bottom</dfn>,
<dfn id=left>left</dfn>.
<li><cite>CSS fragmentation</cite> <a href="#CSS3-BREAK"
rel=biblioentry>[CSS3-BREAK]<!--{{CSS3-BREAK}}--></a> – properties <dfn
id=break-before>break-before</dfn>, <dfn id=break-after>break-after</dfn>
and <dfn id=break-inside>break-inside</dfn>; the definition of <dfn
id=fragmenter>fragmenter</dfn>.
<li><cite>CSS paged media</cite> <a href="#CSS3PAGE"
rel=biblioentry>[CSS3PAGE]<!--{{CSS3PAGE}}--></a> – definition of <dfn
id=page-area>page area</dfn> (in particular its width & height).
<li><cite>CSS background and borders</cite> <a href="#CSS3BG"
rel=biblioentry>[CSS3BG]<!--{{CSS3BG}}--></a> – properties <dfn
id=background>background</dfn>, <dfn