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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "">
<html lang=en>
<head
profile="http://dublincore.org/documents/2008/08/04/dc-html/ http://microformats.org/profile/hcard http://microformats.org/wiki/rel-license">
<meta content="text/html; charset=utf-8" http-equiv=content-type>
<title>CSS Template Layout Module</title>
<link href="http://purl.org/dc/terms/" rel=schema.dcterms>
<link href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=dcterms.rights>
<meta content="CSS Template Layout Module" name=dcterms.title>
<meta content=text name=dcterms.type>
<meta content=2015-09-22 name=dcterms.date>
<meta content="Bert Bos" name=dcterms.creator>
<meta content="César Acebal" name=dcterms.creator>
<meta content=W3C name=dcterms.publisher>
<meta content="http://dev.w3.org/csswg/css-template-3/"
name=dcterms.identifier>
<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}
/* The TR postprocessor already inserted quotes: */
.css::before, .property::before, .descriptor::before {content: none}
.css::after, .property::after, .descriptor::after {content: none}
.prod { font-family: inherit; font-size: inherit }
pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
code { font-size: inherit; }
.example .visible {border: thin dotted silver}
</style>
<link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet>
<body class=h-entry>
<div class=head><!--begin-logo-->
<p><a href="http://www.w3.org/"><img alt=W3C height=48
src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
<h1 class=p-name>CSS Template Layout Module</h1>
<h2 class="no-num no-toc">Editor's Draft 22 September 2015</h2>
<dl>
<dt>This version:
<dd><a class=u-url
href="http://dev.w3.org/csswg/css-template-3/">http://dev.w3.org/csswg/css-template-3/</a>
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css-template-3/">http://www.w3.org/TR/css-template-3/</a>
<dt>Previous version:
<dd><a
href="http://www.w3.org/TR/2015/NOTE-css-template-3-20150326/">http://www.w3.org/TR/2015/NOTE-css-template-3-20150326/</a>
<dt>Feedback:
<dd><a
href="mailto:www-style@w3.org?subject=%5Bcss3-layout%5D%20feedback">www-style@w3.org</a>
with subject line “[css-template-3] <var>… message topic
…</var>” (<a href="http://lists.w3.org/Archives/Public/www-style/"
rel=discussion>archives</a>)
<dt>Editors:
<dd class="p-author h-card vcard"><span class="p-name fn">Bert Bos</span>
(<span class="p-org org h-org">W3C</span>) <a class="u-email email"
href="mailto:bert@w3.org" rel=author>bert@w3.org</a>
<dd class="p-author h-card vcard"><span class="p-name fn">César
Acebal</span> (<span class="p-org org h-org">University of
Oviedo</span>)
<dt>Editors' draft:
<dd><a
href="http://dev.w3.org/csswg/css-template/">http://dev.w3.org/csswg/css-template/</a>
</dl>
<!--begin-copyright-->
<p class=copyright><a
href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
rel=license>Copyright</a> © 2015 <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>). 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 Note
contains experimental ideas for <em>layout templates</em> and alternative
layout models in CSS.
<p>At the moment, it defines a <em>typographic grid</em> for CSS. It has
features to set up a grid-based template, to style the <a
href="#slot"><em>slots</em></a> of the template and to flow content into
them.
<p>A grid template can be seen as a cross between table layout (align
blocks of text automatically in two-dimensions) and absolute positioning
(position elements in arbitrary order), but it also has unique features of
its own.
<p>Grid templates can also be associated with pages in paged media (via
‘<code class=css>@page</code>’), to create <em>page templates.</em>
<p>Slots can form <a href="#chains0"><em>chains,</em></a> to create
non-rectangular regions. A chain of slots is like a series of small pages:
content is broken at possible page breaks and distributed over the slots.
<p><a href="#region-based-styling"><em>Region-based styling</em></a> allows
content to be styled not only based on its position in the document tree,
but also based on the slot it finds itself in. This is achieved by
allowing slot names to appear in selectors.
<!--=================================================================-->
<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=%5Bcss-template-3%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-template-3” in the subject, preferably like this:
“[<!---->css-template-3<!---->] <em>…summary of comment…</em>”
<p>This document was produced by the <a
href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
the <a href="http://www.w3.org/Style/">Style Activity</a>).
<p>This document was produced by a group operating under the <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
2004 W3C Patent Policy</a>. W3C maintains a <a
href="http://www.w3.org/2004/01/pp-impl/32061/status"
rel=disclosure>public list of any patent disclosures</a> made in
connection with the deliverables of the group; that page also includes
instructions for disclosing a patent. An individual who has actual
knowledge of a patent which the individual believes contains <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
Claim(s)</a> must disclose the information in accordance with <a
href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
6 of the W3C Patent Policy</a>.</p>
<!--end-status-->
<p>This draft combines ideas from earlier drafts on Template Layout, Grid
Positioning <a href="#ref-CSS3GRID"
rel=biblioentry>[CSS3GRID]<!--{{CSS3GRID}}--></a> and Grid Layout <a
href="#ref-CSS-GRID-1"
rel=biblioentry>[CSS-GRID-1]<!--{{CSS-GRID-1}}--></a>.
<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> <!-- Decided at Sep 2014 ftf: -->
<p><em>This document currently serves as a repository for ideas around
using templates for laying out elements, regions or pages; and for various
alternative layout models. It is expected to be updated, but it is not
expected to become a W3C Recommendation in this form. Instead, ideas may
migrate to other modules of CSS.</em>
<!--=================================================================-->
<nav id="toc">
<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="#stack-of-cards-layout"><span class=secno>2. </span>Stack of
cards layout</a>
<li><a href="#declaring-templates"><span class=secno>3. </span>Declaring
templates</a>
<ul class=toc>
<li><a href="#grid-template"><span class=secno>3.1. </span>Declaring a
template: ‘<code class=property>grid-template-areas</code>’</a>
<li><a href="#grid-column-sizes"><span class=secno>3.2.
</span>Specifying the widths of columns: ‘<code
class=property>grid-template-columns</code>’</a>
<li><a href="#grid-template-row-sizes"><span class=secno>3.3.
</span>Specifying the height of rows: ‘<code
class=property>grid-template-rows</code>’</a>
<li><a href="#grid-shorthand"><span class=secno>3.4. </span>The ‘<code
class=property>grid</code>’ and ‘<code
class=property>grid-template</code>’ shorthand properties</a>
<li><a href="#default"><span class=secno>3.5. </span>Default slots</a>
<li><a href="#columns"><span class=secno>3.6. </span>Interaction of
‘<code class=property>grid</code>’ and ‘<code
class=property>columns</code>’</a>
<li><a href="#slot-sizes"><span class=secno>3.7. </span>Calculating the
size of the grid</a>
</ul>
<li><a href="#flow"><span class=secno>4. </span>Flowing content into
slots: ‘<code class=property>flow</code>’</a>
<li><a href="#absolute"><span class=secno>5. </span>Comparison with
‘<code class=css>display: grid</code>’ and ‘<code
class=css>display: inline-grid</code>’</a>
<li><a href="#styling-slots"><span class=secno>6. </span>Styling slots</a>
<ul class=toc>
<li><a href="#slot-pseudo"><span class=secno>6.1. </span>The ‘<code
class=css>::slot()</code>’ pseudo-element</a>
<li><a href="#the-blank-pseudo-element"><span class=secno>6.2.
</span>The ‘<code class=css>::blank()</code>’ pseudo-element</a>
<li><a href="#content"><span class=secno>6.3. </span>Slots and the
‘<code class=property>content</code>’ property</a>
</ul>
<li><a href="#region-based"><span class=secno>7. </span>Styling the
contents of slots</a>
<li><a href="#rendering-of-grid-elements"><span class=secno>8.
</span>Rendering of grid elements</a>
<ul class=toc>
<li><a href="#vertical-alignment"><span class=secno>8.1. </span>Vertical
alignment of the contents of slots</a>
<li><a href="#paged"><span class=secno>8.2. </span>Breaking grid
elements across pages or columns</a>
<li><a href="#stacking-order"><span class=secno>8.3. </span>Stacking
order</a>
<li><a href="#floating-elements-inside-templates"><span class=secno>8.4.
</span>Floating elements inside templates</a>
</ul>
<li><a href="#page-templates"><span class=secno>9. </span>Page-based grid
templates</a>
<li><a href="#chains"><span class=secno>10. </span>Chaining slots: the
‘<code class=property>chains</code>’ property</a>
<li><a href="#history"><span class=secno>11. </span>History and
discussion</a>
<ul class=toc>
<li><a href="#developing-a-model-of-declaring-using-st"><span
class=secno>11.1. </span>Developing a model of declaring, using,
styling and resizing grids</a>
<li><a href="#syntax-features-and-levels"><span class=secno>11.2.
</span>Syntax, features and levels</a>
<ul class=toc>
<li><a href="#named-vs-numbered-slots"><span class=secno>11.2.1.
</span>Named vs numbered slots</a>
<li><a href="#single-letter-names-vs-identifiers"><span
class=secno>11.2.2. </span>Single letter names vs identifiers</a>
<li><a href="#quoted-names"><span class=secno>11.2.3. </span>Quote
marks to delimit rows or slot names</a>
<li><a href="#display"><span class=secno>11.2.4. </span>Extend
‘<code class=property>display</code>’ or add a grid property</a>
<li><a href="#combining-columns-and-grids"><span class=secno>11.2.5.
</span>Combining columns and grids</a>
<li><a href="#shorthand-vs-single-property"><span class=secno>11.2.6.
</span>Shorthand vs single property</a>
<li><a href="#the-number-of-rows-and-columns"><span
class=secno>11.2.7. </span>The number of rows and columns</a>
<li><a href="#need-fr"><span class=secno>11.2.8. </span>‘<code
class=css>*</code>’ vs ‘<code class=css>fr</code>’</a>
<li><a href="#auto-add"><span class=secno>11.2.9. </span>Automatically
add rows and columns</a>
<li><a href="#rectangular-slots-vs-non-rectangular-slo"><span
class=secno>11.2.10. </span>Rectangular slots vs non-rectangular
slots</a>
<li><a href="#page-grid"><span class=secno>11.2.11. </span>Page
grids</a>
<li><a href="#style-the-slots-pseudo-elements"><span
class=secno>11.2.12. </span>Style the slots (pseudo-elements)</a>
<li><a href="#select-after-pseudo"><span class=secno>11.2.13.
</span>Style the contents of slots (region-based styling)</a>
<li><a href="#orient-the-grid-with-writing-mode-vs-ori"><span
class=secno>11.2.14. </span>Orient the grid with writing mode vs
orient the slots</a>
<li><a href="#star-or-at-sign"><span class=secno>11.2.15.
</span>Indicating the default slot (‘<code class=css>*</code>’ vs
‘<code class=css>@</code>’)</a>
<li><a href="#abspos"><span class=secno>11.2.16. </span>Flowing vs
absolutely positioning content in a grid</a>
<li><a href="#use-the-pseudo-class-to-create-additiona"><span
class=secno>11.2.17. </span>Use the pseudo-class to create additional
slots</a>
<li><a href="#names-for-edges"><span class=secno>11.2.18. </span>Names
for edges</a>
<li><a href="#position-from-the-right-and-bottom"><span
class=secno>11.2.19. </span>Position from the right and bottom</a>
<li><a href="#syntax-features-to-shorten-long-grid-spe"><span
class=secno>11.2.20. </span>Syntax features to shorten long grid
specifications</a>
<li><a href="#fit-content-vs-auto-vshellip"><span class=secno>11.2.21.
</span>‘<code class=css>fit-content</code>’ vs ‘<code
class=css>auto</code>’ vs…</a>
<li><a href="#vert-align"><span class=secno>11.2.22. </span>Vertical
alignment inside slots</a>
<li><a href="#horizontal-alignment-inside-slots"><span
class=secno>11.2.23. </span>Horizontal alignment inside slots</a>
<li><a href="#auto-margins-on-slots"><span class=secno>11.2.24.
</span>Auto margins on slots</a>
<li><a href="#page-floats"><span class=secno>11.2.25. </span>Page
floats</a>
<li><a href="#break-properties"><span class=secno>11.2.26.
</span>Break-* properties</a>
<li><a href="#next-same"><span class=secno>11.2.27. </span>Automatic
placement of elements</a>
<li><a href="#the-names-of-the-properties"><span class=secno>11.2.28.
</span>The names of the properties</a>
</ul>
</ul>
<li><a href="#conformance"><span class=secno>12. </span>Conformance</a>
<li><a href="#changes"><span class=secno>13. </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-->
</nav>
<!--=================================================================-->
<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 (different number of
columns and rows, different order for the blocks of content, less or more
open space between those blocks, etc.), 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 (or with a page, see below). 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>” or “<span
class=index id=spatial-zones. title="spatial zone">spatial
zones.</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>.”
The horizontal lines of a grid that define the rows are sometimes called
“<span class=index id=flow-lines. title="flow line">flow
lines.</span>” Some traditions make the space between pieces of content
an explicit part of the grid, some consider the space part of the content:
Both styles are possible in CSS, the latter by using the ‘<a
href="#margin"><code class=property>margin</code></a>’ property, the
former by using the ‘<code class=css>.</code>’ symbol in a grid
template.
<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, floats 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>
<p>Paged displays (e.g., printed media) where each page is divided into
fixed areas for different kinds of content.
<li>
<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 (<a
href="#region-based-styling"><em>region-based styling</em></a>).
<li>Paged displays with complex running headers and footers, e.g., running
headers that are in between parts of the page content, rather than at the
edge of the page.
</ul>
<p>Once a grid template has been defined, it can also be used to position
elements without adding them to a flow. Setting ‘<code
class=css>display: grid</code>’ on a grid element makes all children
into separate flows and automatically distributes them over the grid. This
is explained in <cite>CSS Grid Layout</cite> <a href="#ref-CSS-GRID-1"
rel=biblioentry>[CSS-GRID-1]<!--{{!CSS-GRID-1}}--></a>.
<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="#ref-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; <i>width: 100%</i>}</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"; <i>width: fit-content</i>}</pre>
<p>(See <a href="#ref-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 their sizes may
differ. We can make them all the same by adding a rule (see <a
href="#ref-CSS3TBL" rel=biblioentry>[CSS3TBL]<!--{{!CSS3TBL}}--></a>):
<pre>.group {display: table; width: 100%; <i>table-layout: fixed</i>}</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:nth-child(3) {<i>width: 3em</i>}</pre>
<p>resp.,
<pre>.group {grid: <i>* * 3em</i> "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, setting ‘<a href="#display0"><code
class=property>display</code></a>’ to ‘<a href="#grid"><code
class=property>grid</code></a>’ on the grid element creates a different
kind of grid, that <em>does</em> grow, see <a
href="#absolute">“Comparison with ‘<code class=css>display:
grid</code>’ and ‘<code class=css>display:
inline-grid</code>’”</a> below.)
<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; <i>border-collapse: collapse</i>}
.group > div {<i>border: solid</i>}
</pre>
<p>resp.,
<pre>
.group > div {<i>border: solid; border-left: none</i>}
.group > div:first-child {<i>border-left: solid</i>}
</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: <i>c</i>}
.group > div + div {flow: b}
.group > div + div + div {flow: <i>a</i>}
</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 cannot be changed.
</div>
<div class=example>
<p>[Editorial note: Remove this example if the ‘<a
href="#content1"><code class=property>content</code></a>’ property will
<em>not</em> be allowed on elements, as it is currently expected to be.]
<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="#ref-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>
<p>This example shows the use of <a class=index href="#chain."
id=chained-regions title=chain>chained regions:</a> 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 grid 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 {
<a class=index href="#grid" id=grid0>grid</a>: "A A c"
"A A c"
"* * c"
"a b c";
<a
class=index href="#chains0" id=chains1>chains</a>: * 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>
<a class=index href="#atregion" id=atregion0>@region</a> ::slot(*)
{
* {
font-weight: bold;
color: #0C3D5F;
font-size: larger }
h1 {
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="#ref-CSS3GCPM" rel=biblioentry>[CSS3GCPM]<!--{{CSS3GCPM}}--></a>
for some ideas), or there could be a scrollbar on slot c.
</div>
<div class=example>
<p>This example shows 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> [Editorial note: Remove method 3 if <a class=index
href="#vertical-align" id=vertical-align0>vertical-align</a> will
<em>not</em> be generalized to apply to all blocks.]
<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, the second one positioned below the first; 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 is 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.
<p>If, on the other hand, we <em>don't</em> want spaces between the SPANs,
then the question becomes how to get rid of the spaces between the SPANs
in the first row. There are several ways of doing that. One way is to
explicitly flow the three first SPANs to slot “a”:
<pre>span {flow: a}</pre>
<p>The SPANs are thus taken out of the P, causing the P's spaces to end up
next to each other at the start of flow “a” and collapse away.
Another, maybe more intuitive way is to set the spaces to zero width in
the P, and then back to normal in the SPANs (see ‘<a
href="#word-spacing"><code class=property>word-spacing</code></a>’ in
<a href="#ref-CSS-TEXT-3"
rel=biblioentry>[CSS-TEXT-3]<!--{{CSS-TEXT-3}}--></a>):
<pre>
p {word-spacing: -100%}
span {word-spacing: normal}
</pre>
<p>[Editorial note: Remove this last method if percentage values on ‘<a
href="#word-spacing"><code class=property>word-spacing</code></a>’ will
not be allowed. They currently (March 2015) have Working Draft status.]
</div>
<div class=example>
<p>This example uses a <a href="#page-based-template"><em>page-based
template</em></a> to create a running header that is not at the top of
the page, but exactly in the middle. We need to define our own page
template for this, because the predefined page template of <a
href="#ref-CSS3PAGE" rel=biblioentry>[CSS3PAGE]<!--{{CSS3PAGE}}--></a>
only has margin boxes along the edge of the page.
<pre>
@page {
grid:
"top-half"
"running-header" 3em
"bottom-half";
chains: top-half bottom-half
}
::slot(running-header) {
content: "My Magazine - page " counter(page) " - February 2013";
text-align: center;
<a
class=index href="#vertical-align"