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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang="en">
<head>
<title>Tables</title>
<link rel="stylesheet" href="style/default.css" type="text/css">
<link rel="stylesheet" href="http://www.w3.org/StyleSheets/TR/W3C-REC.css" type="text/css">
<link rel="prev" href="text.html">
<link rel="next" href="ui.html">
<link rel="contents" href="cover.html#minitoc">
<link rel="CSS-properties" href="propidx.html" title="properties">
<link rel="index" href="indexlist.html" title="index">
<link rel="first" href="cover.html">
<script src="./annotate.js#CSS21_DEV" type="text/javascript" defer></script>
</head>
<body>
<div class="navbar">
<p><a href="text.html">previous</a>
<a href="ui.html">next</a>
<a href="cover.html#minitoc">contents</a>
<a href="propidx.html">properties</a>
<a href="indexlist.html">index</a>
</div>
<hr class="navbar">
<h1><a name="q0">17 Tables</a></h1>
<div class="subtoc">
<p><strong>Contents</strong>
<ul class="toc">
<li class="tocline2"><a href="tables.html#tables-intro" class="tocxref">17.1 Introduction to tables</a>
<li class="tocline2"><a href="tables.html#table-display" class="tocxref">17.2 The CSS table model</a>
<ul class="toc">
<li class="tocline3"><a href="tables.html#anonymous-boxes" class="tocxref">17.2.1 Anonymous table objects</a>
</ul>
<li class="tocline2"><a href="tables.html#columns" cl
8096
ass="tocxref">17.3 <del>Column selectors</del><ins>Columns</ins></a>
<li class="tocline2"><a href="tables.html#model" class="tocxref">17.4 Tables in the visual formatting model</a>
<ul class="toc">
<li class="tocline3"><a href="tables.html#caption-position" class="tocxref">17.4.1 Caption position and alignment</a>
</ul>
<li class="tocline2"><a href="tables.html#table-layout" class="tocxref">17.5 Visual layout of table contents</a>
<ul class="toc">
<li class="tocline3"><a href="tables.html#table-layers" class="tocxref">17.5.1 Table layers and transparency</a>
<li class="tocline3"><a href="tables.html#width-layout" class="tocxref">17.5.2 Table width algorithms: the <span class="propinst-table-layout">'table-layout'</span> property</a>
<ul class="toc">
<li class="tocline4"><a href="tables.html#fixed-table-layout" class="tocxref"><ins>17.5.2.1</ins> Fixed table layout</a>
<li class="tocline4"><a href="tables.html#auto-table-layout" class="tocxref"><ins>17.5.2.2</ins> Automatic table layout</a>
</ul>
<li class="tocline3"><a href="tables.html#height-layout" class="tocxref">17.5.3 Table height algorithms</a>
<li class="tocline3"><a href="tables.html#column-alignment" class="tocxref">17.5.4 Horizontal alignment in a column</a>
<li class="tocline3"><a href="tables.html#dynamic-effects" class="tocxref">17.5.5 Dynamic row and column effects</a>
</ul>
<li class="tocline2"><a href="tables.html#borders" class="tocxref">17.6 Borders</a>
<ul class="toc">
<li class="tocline3"><a href="tables.html#separated-borders" class="tocxref">17.6.1 The separated borders model</a>
<ul class="toc">
<li class="tocline4"><a href="tables.html#empty-cells" class="tocxref"><ins>17.6.1.1</ins> Borders <ins>and Backgrounds</ins> around empty cells: the <span class="propinst-empty-cells">'empty-cells'</span> property</a>
</ul>
<li class="tocline3"><a href="tables.html#collapsing-borders" class="tocxref">17.6.2 The collapsing border model</a>
<ul class="toc">
<li class="tocline4"><a href="tables.html#border-conflict-resolution" class="tocxref"><ins>17.6.2.1</ins> Border conflict resolution</a>
</ul>
<li class="tocline3"><a href="tables.html#table-border-styles" class="tocxref">17.6.3 Border styles</a>
</ul>
</ul>
</div>
<h2> <del>17.7 Audio rendering of tables 17.7.1 Speaking headers: the 'speak-header' property</del>17.1 <a name="tables-intro">Introduction to tables</a></h2>
<p><ins>This chapter defines the processing model for</ins> tables <ins>in CSS. Part
of this processing model is the layout. For the layout, this chapter
introduces two algorithms; the first, the fixed table layout
algorithm, is well-defined, but the second, the automatic table layout
algorithm, is not fully defined by this specification.</ins>
<p><ins>For the automatic table layout algorithm, some widely deployed
implementations have achieved relatively close interoperability.</ins>
<p><a name="x0"><span class="index-def" title="tables"><ins>Table</ins></span></a> <ins>layout can be
used to</ins> represent <ins>tabular</ins> relationships between data. Authors specify
these relationships in the <a href="conform.html#doclanguage">document
language</a> and <ins>can</ins> specify their <em>presentation</em> <ins>using
CSS 2.1.</ins>
<p><ins>In a visual medium, CSS tables can also be used to achieve specific
layouts.</ins> In <del>CSS,</del><ins>this case, authors should not use table-related elements</ins>
in <del>two ways: visually and aurally.</del><ins>the document language, but should apply the CSS to the relevant
structural elements to achieve the desired layout.</ins>
<p>Authors may specify the visual formatting of a table as a
rectangular grid of cells. Rows and columns of cells may be organized
into row groups and column groups. Rows, columns, row groups, <del>row columns,</del><ins>column
groups,</ins> and cells may have borders drawn around them (there are two
border models in <del>CSS2).</del><ins>CSS 2.1).</ins> Authors may align data vertically or
horizontally within a cell and align data in all cells of a row or
column.
<div class="example"><P style="display:none"> <del>Authors may also specify the aural rendering of a table; how headers and data will be spoken. In the document language, authors may label cells and groups of cells so that when rendered aurally, cell headers are spoken before cell data. In effect, this "serializes" the table: users browsing the table aurally hear a sequence of headers followed by data.</del>Example(s):</P><p>
Here is a simple three-row, three-column
table described in HTML <del>4.0:</del><ins>4:</ins>
<pre class="html-example">
<TABLE>
<CAPTION>This is a simple 3x3 table</CAPTION>
<TR id="row1">
<TH>Header 1 <TD>Cell 1 <TD>Cell 2
<TR id="row2">
<TH>Header 2 <TD>Cell 3 <TD>Cell 4
<TR id="row3">
<TH>Header 3 <TD>Cell 5 <TD>Cell 6
</TABLE>
</pre>
<p>This code creates one table (the TABLE element), three
rows (the TR elements), three header cells (the TH elements),
and six data cells (the TD elements). Note that the three columns
of this example are specified implicitly: there are as many
columns in the table as required by header and data cells.
<p>The following CSS rule centers the text horizontally in the header
cells and <del>present</del><ins>presents</ins> the <del>data</del><ins>text in the header cells</ins> with a bold font
weight:
<pre>
th { text-align: center; font-weight: bold }
</pre>
<p>The next rules align the text of the header cells on their baseline
and vertically <del>centers</del><ins>center</ins> the text in each data cell:
<pre>
th { vertical-align: baseline }
td { vertical-align: middle }
</pre>
<p>The next rules specify that the top row will be surrounded by a 3px
solid blue border and each of the other rows will be surrounded by a
1px solid black border:
<pre>
table { border-collapse: collapse }
tr#row1 { <del>border-top:</del><ins>border:</ins> 3px solid blue }
tr#row2 { <del>border-top:</del><ins>border:</ins> 1px solid black }
tr#row3 { <del>border-top:</del><ins>border:</ins> 1px solid black }
</pre>
<p>Note, however, that the borders around the rows overlap where the
rows meet. What color (black or blue) and thickn
2451
ess (1px or 3px) will
the border between row1 and row2 be? We discuss this in the section on
<a href="#border-conflict-resolution">border conflict resolution.</a>
<p>The following rule puts the table caption above the table:
<pre>
caption { caption-side: top }
</pre>
</div>
<p> <del>Finally, the following rule specifies that, when rendered aurally, each row of data is to be spoken as a "Header, Data, Data": TH { speak-header: once } For instance, the first row would be spoken "Header1 Cell1 Cell2". On the other hand, with the following rule: TH { speak-header: always } it would be spoken "Header1 Cell1 Header1 Cell2".</del>The preceding example shows how CSS works with HTML <del>4.0</del><ins>4</ins> elements;
in HTML <del>4.0,</del><ins>4,</ins> the semantics of the various table elements (TABLE,
CAPTION, THEAD, TBODY, TFOOT, COL, COLGROUP, TH, and TD) are
well-defined. In other document languages (such as XML applications),
there may not be pre-defined table elements. Therefore, <del>CSS2</del><ins>CSS 2.1</ins> allows
authors to <a name="x1"><span class="index-inst" title="mapping elements to table
parts">"map"</span></a> document language elements to table elements via
the <a href="visuren.html#propdef-display" class="noxref"><span class="propinst-display">'display'</span></a> property. For
example, the following rule makes the FOO element act like an HTML
TABLE element and the BAR element act like a CAPTION element:</p>
<PRE class="example">
FOO { display : table }
BAR { display : table-caption }
</pre>
<p><a name="internal"></a> We discuss the various table elements in the
following section. In
this specification, the term <a name="x2"><span class="index-def" title="table
element"><dfn>table element</dfn></span></a> refers to any element
involved in the creation of a table. An <a name="x3"><span class="index-def"
title="internal table element|table element::internal"><dfn id="internal-table-element"> <del>"internal"</del><ins>internal</ins>
table element</dfn></span></a> is one that produces a row, row group, column,
column group, or cell.
<h2>17.2 <a name="table-display">The CSS table model</a></h2>
<p>The CSS table model is based on the <del>HTML 4.0</del><ins>HTML4</ins> table model, in
which the structure of a table closely parallels the visual layout of
the table. In this model, a table consists of an optional caption and
any number of rows of cells. The table model is said to be "row
primary" since authors specify rows, not columns, explicitly in the
document language. Columns are derived once all the rows have been
specified -- the first cell of each row belongs to the first column,
the second to the second column, etc.). Rows and columns may be
grouped structurally and this grouping reflected in presentation
(e.g., a border may be drawn around a group of rows).
<p>Thus, the table model consists of tables, captions, rows, <a name="x5"><span
class=index-def>row <del>groups,</del><ins>groups</ins></span></a> <ins>(including header groups and footer
groups),</ins> columns, column groups, and cells.
<p>The CSS model does not require that the <a
href="conform.html#doclanguage">document language</a> include elements
that correspond to each of these components. For document languages
(such as XML applications) that do not have pre-defined table
elements, authors must map document language elements to table
elements; this is done with the <a href="visuren.html#propdef-display" class="noxref"><span
class="propinst-display">'display'</span></a> property. The following
<a href="visuren.html#propdef-display" class="noxref"><span class="propinst-display">'display'</span></a> values assign table
<del>semantics</del><ins>formatting rules</ins> to an arbitrary element:
<dl>
<dt><strong><span class="index-def" title="table"><a
class="value-def" name="value-def-table">table</a></span></strong>
(In HTML: TABLE) <dd>Specifies that an element defines a <a
href="visuren.html#block-level">block-level</a> table: it is a
rectangular block that participates in a <a
href="visuren.html#block-formatting">block formatting context</a>.
<dt><strong><span class="index-def" title="inline-table"><a
class="value-def"
name="value-def-inline-table">inline-table</a></span></strong> (In
HTML: TABLE) <dd>Specifies that an element defines an <a
href="visuren.html#inline-level">inline-level</a> table: it is a
rectangular block that participates in an <a
href="visuren.html#inline-formatting">inline formatting
context</a>).
<dt><strong><span class="index-def" title="table-row"><a
class="value-def"
name="value-def-table-row">table-row</a></span></strong> (In HTML:
TR) <dd>Specifies that an element is a row of cells.
<dt><strong><span class="index-def" title="table-row-group"><a
class="value-def"
name="value-def-table-row-group">table-row-group</a></span></strong>
(In HTML: TBODY) <dd>Specifies that an element groups one or more
rows.
<dt><strong><span class="index-def" title="table-header-group"><a
class="value-def"
name="value-def-table-header-group">table-header-group</a></span></strong>
(In HTML: THEAD) <dd>Like 'table-row-group', but for visual
formatting, the row group is always displayed before all other rows
and <del>rowgroups</del><ins>row groups</ins> and after any top captions. Print user agents may
repeat <del>footer</del><ins>header</ins> rows on each page spanned by a table. <ins>If a table
contains multiple elements with 'display: table-header-group', only
the first is rendered as a header; the others are treated as if they
had 'display: table-row-group'.</ins>
<dt><strong><span class="index-def" title="table-footer-group"><a
class="value-def"
name="value-def-table-footer-group">table-footer-group</a></span></strong>
(In HTML: TFOOT) <dd>Like 'table-row-group', but for visual
formatting, the row group is always displayed after all other rows
and <del>rowgroups</del><ins>row groups</ins> and before any bottom captions. Print user agents may
repeat footer rows on each page spanned by a table. <del>table-column (In HTML: COL) Specifies that an element describes</del><ins>If</ins> a <del>column of cells. table-column-group (In HTML: COLGROUP) Specifies that an element</del><ins>table
contains multiple elements with 'display: table-footer-group', only
the first is rendered as a footer; the others are treated as if they
had 'display: table-row-group'.</ins>
<dt><strong><span class="index-def" title="table-column"><a
class="value-def"
name="value-def-table-column"><ins>table-column</ins></a></span></strong> <ins>(In
HTML: COL)</ins> <dd><ins>Specifies that an element describes a column of
cells.</ins>
<dt><strong><span class="index-def" title="table-column-group"><a
class="value-def"
name="value-def-table-column-group"><ins>table-column-group</ins></a></span></strong>
<ins>(In HTML: COLGROUP)</ins> <dd><ins>Specifies that an element</ins> groups one or more
columns.
<dt><strong><span class="index-def" title="table-cell"><a
class="value-def"
name="value-def-table-cell">table-cell</a></span></strong> (In HTML:
TD, TH) <dd>Specifies that an element represents a table cell.
<dt><strong><span class="index-def" title="table-caption"><a
class="value-def"
name="value-def-table-caption">table-caption</a></span></strong> (In
HTML: CAPTION) <dd>Specifies a caption for the table. <ins>All elements
with 'display: table-caption' must be rendered, as described in</ins>
<a href="#model"><ins>section 17.4.</ins></a>
</dl>
<p><ins>Replaced elements with these</ins> <a href="visuren.html#propdef-display" class="noxref"><span
class="propinst-display"><ins>'display'</ins></span></a> <ins>values are treated as their
given display types during layout. For example, an image that is set
to 'display: table-cell' will fill the available cell space, and its
dimensions might contribute towards the table sizing algorithms, as
with an ordinary cell.</ins>
<p>Elements with <a href="visuren.html#propdef-display" class="noxref"><span class="propinst-display">'display'</span></a> set
to 'table-column' or 'table-column-group' are not rendered (exactly as
if they had 'display: none'), but they are useful, because they may
have attributes which induce a certain style for the columns they
represent.
<p>The <a href="sample.html">default style sheet for <del>HTML 4.0</del><ins>HTML4</ins></a>
in the appendix illustrates the use of these values for <del>HTML 4.0:</del><ins>HTML4:</ins>
<pre class="example">
table { display: table }
tr { display: table-row }
thead { display: table-header-group }
tbody { display: table-row-group }
tfoot { display: table-footer-group }
col { display: table-column }
colgroup { display: table-column-group }
td, th { display: table-cell }
caption { display: table-caption }
</pre>
<p>User agents may <a href="syndata.html#ignore">ignore</a> these
<a href="visuren.html#propdef-display" class="noxref"><span class="propinst-display">'display'</span></a> property values for
HTML <del>documents,</del><ins>table elements,</ins> since <del>authors should</del><ins>HTML tables may be rendered using other
algorithms intended for backwards compatible rendering. However, this
is</ins> not <del>alter an element's expected behavior.</del><ins>meant to discourage the use of 'display: table' on other,
non-table elements in HTML.</ins>
<h3>17.2.1 <a name="anonymous-boxes">Anonymous table objects</a></h3>
<p>Document languages other than HTML may not contain all the elements
in the <del>CSS2</del><ins>CSS 2.1</ins> table model. In these cases, the "missing"
elements must be assumed in order for the table model to work. <del>The missing elements generate anonymous objects (e.g., anonymous boxes in visual table layout) according to the following rules:</del>Any
table element will automatically generate necessary anonymous table
objects around itself, consisting of at least three nested objects
corresponding to a 'table'/'inline-table' element, a 'table-row'
element, and a 'table-cell' element. <del>If the parent P of a 'table-cell' element T is not a 'table-row', an object corresponding</del><ins>Missing elements generate</ins> <a
href="visuren.html#anonymous"><ins>anonymous</ins></a> <ins>objects (e.g., anonymous
boxes in visual table layout) according</ins> to <del>a 'table-row' will be generated between P and T. This object will span all consecutive 'table-cell' siblings (in</del>the <del>document tree) of T. If</del><ins>following rules:</ins>
<p><ins>For</ins> the <del>parent P</del><ins>purposes</ins> of <del>a 'table-row' element T is not a 'table', 'inline-table', or 'table-row-group' element, an object corresponding to a 'table' element will be generated between P and T. This object will span all consecutive siblings (in</del><ins>these rules,</ins> the <del>document tree) of T that require</del><ins>following terms are defined:</ins>
<dl>
<dt><a name="x16"><span class="index-def"><ins>row group box</ins></span></a>
<dd>A <del>'table' parent: 'table-row',</del>'table-row-group', 'table-header-group', <del>'table-footer-group', 'table-column', 'table-column-group', and 'caption'. If the parent P of a 'table-row-group' (or 'table-header-group' or 'table-footer-group') element T is not a 'table'</del>or
<del>'inline-table', an object corresponding to</del><ins>'table-footer-group'</ins>
<dt><a name="x17"><span class="index-def"><ins>proper table child</ins></span></a>
<dd>A <del>'table' element will be generated between P and T. This object will span all</del><ins>'table-row' box, row group box, 'table-column' box,
'table-column-group' box, or 'table-caption' box.</ins>
<dt><a name="x18"><span class="index-def"><ins>proper table row parent</ins></span></a>
<dd><ins>A 'table' or 'inline-table' box or row group box</ins>
<dt><a name="x19"><span class="index-def"><ins>internal table box</ins></span></a>
<dd><ins>A 'table-cell' box, 'table-row' box, row group box,
'table-column' box, or 'table-column-group' box.</ins>
<dt id="tabular-container"><a name="x20"><span class="index-def"><ins>tabular container</ins></span></a>
<dd><ins>A 'table-row' box or proper table row parent</ins>
<dt><a name="x21"><span class="index-def"><ins>consecutive</ins></span></a>
<dd><ins>Two sibling boxes are</ins> consecutive <ins>if they have no intervening</ins>
siblings <del>(in</del><ins>other than, optionally, an anonymous inline containing
only white spaces. A sequence of sibling boxes is consecutive if
each box in</ins> the <del>document tree)</del><ins>sequence is consecutive to the one before it in
the sequence.</ins>
</dl>
<p><ins>For the purposes</ins> of <del>T that require a 'table' parent: 'table-row', 'table-row-group', 'table-header-group', 'table-footer-group', 'table-column', 'table-column-group',</del><ins>these rules, out-of-flow elements are
represented as inline elements of zero width</ins> and <del>'caption'.</del><ins>height. Their
containing blocks are chosen accordingly.</ins>
<p><ins>The following steps are performed in three stages.</ins>
<ol>
<li><ins>Remove irrelevant boxes:</ins>
<ol>
<li><ins>All child boxes of a 'table-column' parent are treated as if
they had 'display: none'.</ins>
<li>If a child <var> <del>T</del><ins>C</ins></var> of a <del>'table-row' element P</del><ins>'table-column-group' parent</ins> is
not a <del>'table-cell' element, an object corresponding to</del><ins>'table-column' box, then it is treated as if it had
'display: none'.</ins>
2451
<li><ins>If</ins> a <del>'table-cell' element will be generated between</del><ins>child</ins> <var><ins>C</ins></var> <ins>of a tabular container</ins> <var>P</var>
<ins>is an anonymous inline box that contains only white space,</ins>
and <del>T. This object spans all consecutive siblings</del><ins>its immediately preceding and following siblings, if
any, are proper table descendants</ins> of <var> <del>T that</del><ins>P</ins></var> <ins>and</ins> are
<del>not 'table-cell' elements. Example(s): In this XML example,</del><ins>either 'table-caption' or internal table boxes, then it is
treated as if it had 'display: none'.</ins> A <del>'table' element</del><ins>box</ins> <var><ins>D</ins></var> is
<del>assumed to contain the HBOX element: <HBOX> <VBOX>George</VBOX> <VBOX>4287</VBOX> <VBOX>1998</VBOX> </HBOX> because</del><ins>a proper table descendant of</ins> <var><ins>A</ins></var> <ins>if</ins> <var><ins>D</ins></var>
<ins>can be a descendant of</ins> <var><ins>A</ins></var> <ins>without causing</ins> the
<del>associated style sheet is: HBOX {</del><ins>generation of any intervening 'table' or 'inline-table'
boxes.</ins>
<li><ins>If a box</ins> <var><ins>B</ins></var> <ins>is an anonymous inline containing only
white space, and is between two immediate siblings each of
which is either an internal table box or a 'table-caption'
box then</ins> <var><ins>B</ins></var> <ins>is treated as if it had 'display:
none'.</ins>
</ol>
<li><ins>Generate missing child wrappers:</ins>
<ol>
<li><ins>If a child</ins> <var><ins>C</ins></var> <ins>of a 'table' or 'inline-table' box
is not a proper table child, then generate an anonymous
'table-row' box around</ins> <var><ins>C</ins></var> <ins>and all consecutive
siblings of</ins> <var><ins>C</ins></var> <ins>that are not proper table children.</ins>
<li><ins>If a child</ins> <var><ins>C</ins></var> <ins>of a row group box is not a
'table-row' box, then generate an anonymous 'table-row' box
around</ins> <var><ins>C<
7C59
/ins></var> <ins>and all consecutive siblings
of</ins> <var><ins>C</ins></var> <ins>that are not 'table-row' boxes.</ins>
<li><ins>If a child</ins> <var><ins>C</ins></var> <ins>of a 'table-row' box is not a
'table-cell', then generate an anonymous 'table-cell' box
around</ins> <var><ins>C</ins></var> <ins>and all consecutive siblings
of</ins> <var><ins>C</ins></var> <ins>that are not 'table-cell' boxes.</ins>
</ol>
<li><ins>Generate missing parents:</ins>
<ol>
<li><ins>For each 'table-cell' box</ins> <var><ins>C</ins></var> <ins>in a sequence of
consecutive internal table and 'table-caption' siblings,
if</ins> <var><ins>C</ins></var><ins>'s parent is not a 'table-row' then generate
an anonymous 'table-row' box around</ins> <var><ins>C</ins></var> <ins>and all
consecutive siblings of</ins> <var><ins>C</ins></var> <ins>that are 'table-cell'
boxes.</ins>
<li><ins>For each proper table child</ins> <var><ins>C</ins></var> <ins>in a sequence of
consecutive proper table children, if</ins> <var><ins>C</ins></var> <ins>is
misparented then generate an anonymous 'table' or
'inline-table' box</ins> <var><ins>T</ins></var> <ins>around</ins> <var><ins>C</ins></var> <ins>and all
consecutive siblings of</ins> <var><ins>C</ins></var> <ins>that are proper table
children. (If C's parent is an 'inline' box,
then</ins> <var><ins>T</ins></var> <ins>must be an 'inline-table' box; otherwise
it must be a 'table' box.)</ins>
<ul>
<li><ins>A 'table-row' is misparented if its parent is neither
a row group box nor a 'table' or 'inline-table' box.</ins>
<li><ins>A 'table-column' box is misparented if its parent is
neither a 'table-column-group' box nor a 'table' or
'inline-table' box.</ins>
<li><ins>A row group box, 'table-column-group' box, or
'table-caption' box is misparented if its parent is
neither a 'table' box nor an 'inline-table' box.</ins>
</ul>
</ol>
</ol>
<div class="example"><P style="display:none"><ins>Example(s):</ins></P>
<p><ins>In this XML example, a 'table' element is assumed to contain the
HBOX element:</ins>
<pre class="xml-example">
<ins><HBOX>
<VBOX>George</VBOX>
<VBOX>4287</VBOX>
<VBOX>1998</VBOX>
</HBOX></ins>
</pre>
<p><ins>because the associated style sheet is:</ins>
<pre class="example">
<ins>HBOX {</ins> display: table-row }
VBOX { display: table-cell }
</pre>
</div>
<div class="example"><P style="display:none">Example(s):</P>
<p>In this example, three 'table-cell' elements are assumed to contain
the text in the ROWs. Note that the text is further encapsulated in
anonymous inline boxes, as explained in <a
href="visuren.html#anonymous">visual formatting model</a>:
<pre class="xml-example">
<STACK>
<ROW>This is the <D>top</D> row.</ROW>
<ROW>This is the <D>middle</D> row.</ROW>
<ROW>This is the <D>bottom</D> row.</ROW>
</STACK>
</pre>
<p>The style sheet is:
<pre class="example">
STACK { display: inline-table }
ROW { display: table-row }
D { display: inline; font-weight: bolder }
</pre>
</div>
<h2> <del>HTML user agents are not required to create anonymous objects according to the above rules.</del>17.3 <a name="columns"> <del>Column selectors</del><ins>Columns</ins></a></h2>
<p>Table cells may belong to two contexts: rows and columns. However,
in the source document cells are descendants of rows, never of
columns. Nevertheless, some aspects of cells can be influenced by
setting properties on columns.
<p>The following properties apply to column and column-group elements:
<dl>
<dt><a href="box.html#propdef-border" class="noxref"><span class="propinst-border">'border'</span></a>
<dd>The various border properties apply to columns only if <a href="tables.html#propdef-border-collapse" class="noxref"><span
class="propinst-border-collapse">'border-collapse'</span></a> is set
to 'collapse' on the table element. In that case, borders set on
columns and column groups are input to the <a
href="#border-conflict-resolution">conflict resolution
algorithm</a> that selects the border styles at every cell edge.
<dt><a href="colors.html#propdef-background" class="noxref"><span class="propinst-background">'background'</span></a>
<dd>The background properties set the background for cells in the
column, but only if both the cell and row have transparent
backgrounds. See <a href="#table-layers">"Table layers and
transparency."</a>
<dt><a href="visudet.html#propdef-width" class="noxref"><span class="propinst-width">'width'</span></a>
<dd>The <a href="visudet.html#propdef-width" class="noxref"><span class="propinst-width">'width'</span></a> property gives
the minimum width for the column.
<dt><a href="visufx.html#propdef-visibility" class="noxref"><span class="propinst-visibility">'visibility'</span></a>
<dd>If the 'visibility' of a column is set to 'collapse', none of
the cells in the column are rendered, and cells that span into
other columns are clipped. In addition, the width of the table is
diminished by the width the column would have taken up. See <a
href="#dynamic-effects">"Dynamic effects"</a> below. Other values
for 'visibility' have no effect.
</dl>
<div class="example"><P style="display:none">Example(s):</P>
<p>Here are some examples of style rules that set properties on
columns. The first two rules together implement the "rules" attribute
of HTML <del>4.0</del><ins>4</ins> with a value of "cols". The third rule makes the "totals"
column blue, the final two rules shows how to make a column a fixed
size, by using the <a href="#fixed-table-layout">fixed layout
algorithm</a>.
<pre>
col { border-style: none solid }
table { border-style: hidden }
col.totals { background: blue }
table { table-layout: fixed }
col.totals { width: 5em }
</pre>
</div>
<h2>17.4 <a name="model">Tables in the visual <del>formatting model In terms of the visual formatting model , a table may behave like a block-level or replaced inline-level element. Tables have content, padding, borders, and margins. In both cases, the table element generates an anonymous box that contains the table box itself and the caption's box (if present). The table and caption boxes retain their own content, padding, margin, and border areas, and the dimensions of the rectangular anonymous box are the smallest required to contain both. Vertical margins collapse where the table box and caption box touch. Any repositioning of the table must move the entire anonymous box, not just the table box, so that the caption follows the table. [D] Diagram of a table with a caption above it; the bottom margin of the caption is collapsed with the top margin of the table. 17.4.1 Caption position and alignment 'caption-side' Value: top | bottom | left | right | inherit Initial: top Applies to: 'table-caption' elements Inherited: yes Percentages: N/A Media: visual This property specifies the position</del><ins>formatting model</ins></a></h2>
<p><ins>In terms</ins> of the <del>caption box with respect to the</del><ins>visual formatting model, a</ins> table <del>box. Values have the following meanings: top Positions</del><ins>can behave like a</ins>
<a href="visuren.html#block-level"><ins>block-level</ins></a> <ins>(for 'display:
table') or</ins> <a href="visuren.html#inline-level"><ins>inline-level</ins></a> <ins>(for
'display: inline-table') element.</ins>
<p><ins>In both cases,</ins> the <del>caption</del><ins>table generates a principal block</ins> box <del>above</del><ins>called</ins> the
<dfn>table <del>box. bottom Positions the caption</del><ins>wrapper</ins> box</dfn> <del>below</del><ins>that
contains</ins> the table <del>box. left Positions the caption</del>box <del>to</del><ins>itself and any caption boxes (in document
order).</ins>
The <dfn> <del>left of</del><ins>table box</ins></dfn> <ins>is a block-level box that contains</ins> the
<ins>table's internal</ins> table <del>box. right Positions</del><ins>boxes.</ins>
The caption <del>box to the right of</del><ins>boxes are block-level boxes that retain their own
content, padding, margin, and border areas, and are rendered as normal
block boxes inside</ins> the table <ins>wrapper</ins> box. <del>Captions above or below a 'table' element</del><ins>Whether the caption boxes</ins> are <del>formatted very much as if they were a block element</del><ins>placed</ins>
before or after the <del>table, except that (1) they inherit inheritable properties from the table, and (2) they are not considered to be a block</del><ins>table</ins> box <del>for</del><ins>is decided by</ins> the <del>purposes of any 'compact' or 'run-in' element that may precede</del><ins>'caption-side'
property, as described below.</ins>
<p>The <del>table. A caption that is above or below a</del>table <ins>wrapper</ins> box <del>also behaves like</del><ins>is</ins> a <del>block</del><ins>'block'</ins> box <del>for width calculations;</del><ins>if</ins> the <del>width</del><ins>table</ins> is <del>computed with respect to the width of</del><ins>block-level, and
an 'inline-block' box if</ins> the table <del>box's containing block. For a caption that</del>is <del>on</del><ins>inline-level.</ins> The <del>left or right side of a</del>table <del>box, on the other hand, a value other than 'auto' for 'width' sets the width explicitly, but 'auto' tells the user agent to chose</del><ins>wrapper box
establishes</ins> a <del>"reasonable width". This may vary between "the narrowest possible box" to "a single line", so we recommend that users do not specify 'auto' for left and right caption widths. To align caption content horizontally within the caption box, use</del><ins>block formatting context.</ins> The <del>'text-align' property. For</del><ins>table box (not the
table wrapper box) is used when doing baseline</ins>
vertical alignment <ins>for an 'inline-table'. The width</ins> of <del>a left or right caption</del><ins>the table wrapper</ins>
box <del>with respect</del><ins>is the border-edge width of the table box inside it, as described
by section 17.5.2. Percentages on 'width' and 'height' on the table are
relative</ins> to the table <del>box, use</del><ins>wrapper box's containing block, not</ins> the <del>'vertical-align' property.</del><ins>table wrapper box
itself.</ins>
<p>The <del>only meaningful</del><ins>computed</ins> values <del>in this case are</del><ins>of properties 'position', 'float', 'margin-*',</ins>
'top', <del>'middle',</del><ins>'right', 'bottom',</ins> and <del>'bottom'.</del><ins>'left' on the table element are used on
the table wrapper box and not the table box;</ins> all other values <ins>of
non-inheritable properties</ins> are <del>treated</del><ins>used on</ins> the <del>same as 'top'. Example(s): In this example,</del><ins>table box and not</ins> the <del>'caption-side' property places captions below tables.</del><ins>table
wrapper box. (Where the table element's values are not used on the
table and table wrapper boxes,</ins> the <ins>initial values are used instead.)</ins>
<div class="figure">
<p><img src="images/table_container.png" alt="A table with a caption above
it">
<p class="caption"><ins>Diagram of a table with a</ins> caption <del>will be as wide</del><ins>above it.</ins>
</div>
<h3><ins>17.4.1</ins> <a name="caption-position"><ins>Caption position and alignment</ins></a></h3>
<div class="propdef">
<dl><dt>
<span class="index-def" title="'caption-side'"><a name="propdef-caption-side" class="propdef-title"><strong><ins>'caption-side'</ins></strong></a></span>
<dd>
<table class="propinfo" cellspacing=0 cellpadding=0>
<tr valign=baseline><td><em><ins>Value:</ins></em><ins> </ins><td><ins>top | bottom |</ins> <a href="cascade.html#value-def-inherit" class="noxref"><span class="value-inst-inherit"><ins>inherit</ins></span></a>
<tr valign=baseline><td><em><ins>Initial:</ins></em><ins> </ins><td><ins>top</ins>
<tr valign=baseline><td><em><ins>Applies to:</ins></em><ins> </ins><td><ins>'table-caption' elements</ins>
<tr valign=baseline><td><em><ins>Inherited:</ins></em><ins> </ins><td><ins>yes</ins>
<tr valign=baseline><td><em><ins>Percentages:</ins></em><ins> </ins><td><ins>N/A</ins>
<tr valign=baseline><td><em><ins>Media:</ins></em><ins> </ins><td><a href="media.html#visual-media-group" class="noxref"><ins>visual</ins></a>
<tr valign=baseline><td><em><ins>Computed value:</ins></em><ins> </ins><td>as <ins>specified</ins>
</table>
</dl>
</div>
<p><ins>This property specifies</ins> the <del>parent</del><ins>position</ins> of the <del>table, and</del>caption <del>text will be left-justified. CAPTION { caption-side: bottom; width: auto; text-align: left } Example(s):</del><ins>box with
respect to the table box. Values have</ins> the following <del>example shows how to put a caption in</del><ins>meanings:</ins>
<dl>
<dt><strong><ins>top</ins></strong> <dd><ins>Positions</ins> the <del>left margin.</del><ins>caption box above</ins> the
table <del>itself is centered, by setting its left and right margins to 'auto', and</del><ins>box.</ins>
<dt><strong><ins>bottom</ins></strong> <dd><ins>Positions</ins> the <del>whole</del><ins>caption</ins> box <del>with</del><ins>below the</ins>
table <ins>box.</ins>
</dl>
<div class=note>
<p><em><strong><ins>Note:</ins></strong> <ins>CSS2 described a different width and
horizontal alignment behavior. That behavior will be introduced in
CSS3 using the values 'top-outside'</ins> and <ins>'bottom-outside' on this
property.</ins></em>
</div>
<p><ins>To align</ins> caption <del>is shifted into</del><ins>content horizontally within the caption box, use</ins>
the <a href="text.html#propdef-text-align" class="noxref"><span class="propinst-text-align"> <del>left margin by</del><ins>'text-align'</ins></span></a> <ins>property.</ins>
<div class="example"><P style="display:none"><ins>Example(s):</ins></P>
<p><ins>In this example,</ins> the <a href="tables.html#propdef-caption-side" class="noxref"><span
class="propinst-caption-side"> <del>same amount</del><ins>'caption-side'</ins></span></a> <ins>property places
captions below tables. The caption will be as wide</ins> as the <del>width</del><ins>parent</ins> of
the <del>caption. BODY { margin-left: 8em } TABLE { margin-left: auto; margin-right: auto }</del><ins>table, and caption text will be left-justified.</ins>
<pre>
caption { caption-side: <del>left; margin-left: -8em;</del><ins>bottom;</ins>
width: <del>8em;</del><ins>auto;</ins>
text-align: <del>right; vertical-align: bottom } Assuming the width of the table is less than the available width, the formatting will be similar to this: [D] Diagram showing a centered table with the caption extending into the</del>left <del>margin, as a result of a negative 'margin-left' property.</del><ins>}</ins>
</pre>
</div>
<h2>17.5 <a name="table-layout">Visual layout of table contents</a></h2>
<p> <del>Like other elements of the document language ,</del>Internal table elements generate rectangular <a
href="box.html#box-dimensions">boxes</a> with <del>content, padding,</del><ins>content</ins> and borders.
<del>They</del><ins>Cells have padding as well. Internal table elements</ins> do not have
<del>margins, however.</del><ins>margins.</ins>
<p>The visual layout of these boxes is governed by a rectangular,
irregular grid of rows and columns. Each box occupies a whole number
of grid cells, determined according to the following rules. These
rules do not apply to HTML <del>4.0</del><ins>4</ins> or earlier HTML versions; HTML imposes
its own limitations on row and column spans.
<ol>
<li>Each row box occupies one row of grid cells. Together, the row
boxes fill the table from top to bottom in the order they occur in
the source document (i.e., the table occupies exactly as many grid
rows as there are row elements).
<li>A row group occupies the same grid cells as the rows it
contains.
<li>A column box occupies one or more columns of grid cells. Column
boxes are placed next to each other in the order they occur. The
first column box may be either on the left or on the right,
depending on the value of the <a href="visuren.html#propdef-direction" class="noxref"><span
class="propinst-direction">'direction'</span></a> property of the table.
<li>A column group box occupies the same grid cells as the columns
it contains.
<li>Cells may span several rows or columns. (Although <del>CSS2 doesn't</del><ins>CSS 2.1
does not</ins> define how the number of spanned rows or columns is
determined, a user agent may have special knowledge about the source
document; a future <del>version</del><ins>update</ins> of CSS may provide a way to express this
knowledge in CSS syntax.) Each cell is thus a rectangular box, one
or more grid cells wide and high. The top row of this rectangle is
in the row specified by the cell's parent. The rectangle must be as
far to the left as possible, but <ins>the part of the cell in the first
column</ins> it <del>may</del><ins>occupies must</ins> not overlap with any other cell <del>box,</del><ins>box (i.e., a
row-spanning cell starting in a prior row),</ins> and <ins>the cell</ins> must be to
the right of all cells in the same row that are earlier in the
source document. <ins>If this position would cause a column-spanning cell
to overlap a row-spanning cell from a prior row, CSS does not define
the results: implementations may either overlap the cells (as is
done in many HTML implementations) or may shift the later cell to
the right to avoid such overlap.</ins> (This constraint holds if the
'direction' property of the table is 'ltr'; if the 'direction' is
'rtl', interchange "left" and "right" in the previous <del>sentence.)</del><ins>two
sentences.)</ins>
<li>A cell box cannot extend beyond the last row box of a table or
<del>row-group;</del><ins>row group;</ins> the user agents must shorten it until it fits.
</ol>
<p> <del>Note. Table</del><ins>The edges of the rows, columns, row groups and column groups in the</ins>
<a href="#collapsing-borders"><ins>collapsing borders model</ins></a> <ins>coincide
with the hypothetical grid lines on which the borders of the</ins> cells <ins>are
centered. (And thus, in this model, the rows together exactly cover
the table, leaving no gaps; ditto for the columns.) In the</ins> <a
href="#separated-borders"><ins>separated borders model,</ins></a> <ins>the edges
coincide with the</ins> <a href="box.html#border-edge"><ins>border edges</ins></a> <ins>of
cells. (And thus, in this model, there</ins> may be <del>relatively</del><ins>gaps between the rows,
columns, row groups or column groups, corresponding to the</ins> <a href="tables.html#propdef-border-spacing" class="noxref"><span
class="propinst-border-spacing"><ins>'border-spacing'</ins></span></a> <ins>property.)</ins>
<div class="note">
<p><em><strong><ins>Note.</ins></strong> <ins>Positioning</ins> and <del>absolutely positioned, but this is</del><ins>floating of table cells
can cause them</ins> not <del>recommended: positioning and</del><ins>to be table cells anymore, according to the rules
in</ins> <a href="visuren.html#dis-pos-flo"><ins>section 9.7</ins></a><ins>. When</ins> floating
<del>remove a box from</del><ins>is used,</ins> the <a> <del>flow, affecting</del><ins>rules on anonymous</ins> table <del>alignment.</del><ins>objects</ins></a> <ins>may cause an
anonymous cell object to be created as well.</ins></em>
</div>
<div class="html-example">
<p>Here <del>are two examples. The first</del>is <del>assumed to occur in</del>an <del>HTML document:</del><ins>example illustrating rule 5. The following illegal
(X)HTML snippet defines conflicting cells:</ins>
<pre>
<table>
<tr><td>1 <del><TD</del><ins></td><td</ins> rowspan="2">2 <del><TD>3 <TD>4</del><ins></td><td>3 </td><td>4 </td></tr></ins>
<tr><td colspan="2">5 <ins></td></tr></ins>
</table>
</pre>
<p> <del><TABLE> <ROW><CELL>1 <CELL rowspan="2">2 <CELL>3 <CELL>4 <ROW><CELL colspan="2">5 </TABLE></del><ins>User agents are free to visually overlap</ins> the <del>second table is formatted</del><ins>cells,</ins> as in the
figure on the <del>right. However, the HTML table's rendering is explicitly undefined by HTML, and CSS doesn't try</del><ins>left, or</ins> to <del>define it. User agents are free</del><ins>shift the cell</ins> to <del>render it, e.g.,</del><ins>avoid the visual
overlap,</ins> as in the figure
8096
on the <del>left.</del><ins>right.</ins>
<div class="figure">
<p><img src="images/table-overlap.png" alt="One table with overlapping
cells and one without"><SPAN class="dlink"> <A name="img-table-overlap" href="images/longdesc/table-overlap-desc.html" title="Long description for example showing how structurally
overlapping cells are rendered">[D]</A></SPAN> <p class="caption"> <del>On the left, one</del><ins>Two</ins> possible
<del>rendering</del><ins>renderings</ins> of an erroneous HTML <del>4.0 table; on the right, the only possible formatting of a similar, non-HTML</del>table.
</div>
</div>
<h3>17.5.1 <a name="table-layers">Table layers and transparency</a></h3>
<p>For the purposes of finding the background of each table cell, the
different table elements may be thought of as being on six
superimposed layers. The background set on an element in one of the
layers will only be visible if the layers above it have a transparent
background.
<div class="figure">
<p><img src="images/tbl-layers.png" alt="schema of table layers"><SPAN class="dlink"> <A name="img-tbl-layers" href="images/longdesc/tbl-layers-desc.html" title="Long description of example of cell background calculation">[D]</A></SPAN>
<p class="caption">Schema of table layers.
</div>
<ol>
<li>The lowest layer is a single plane, representing the table box
itself. Like all boxes, it may be transparent.
<li>The next layer contains the column groups. <ins>Each column group
extends from</ins> the <del>columns groups are as tall as</del><ins>top of</ins> the <del>table, but</del><ins>cells in the top row to the bottom of
the cells on the bottom row and from the left edge of its leftmost
column to the right edge of its rightmost column. The background
covers exactly the full area of all cells that originate in the
column group, even if</ins> they <del>need not cover</del><ins>span outside</ins> the <del>whole table horizontally.</del><ins>column group, but this
difference in area does not affect background image positioning.</ins>
<li>On top of the column groups are the areas representing the
column boxes. <del>Like</del><ins>Each</ins> column <del>groups, columns are</del><ins>is</ins> as tall as the <del>table, but need not cover</del><ins>column groups and as
wide as a normal (single-column-spanning) cell in the column. The
background covers exactly the full area of all cells that originate
in the column, even if they span outside the column, but this
difference in area does not affect background image positioning.</ins>
<li><ins>Next is the layer containing the row groups. Each row group
extends from the top left corner of its topmost cell in the first
column to the bottom right corner of its bottommost cell in the last
column.</ins>
<li>The <del>whole table horizontally.</del>next <del>is the</del><ins>to last</ins> layer <del>containing</del><ins>contains</ins> the <del>row groups.</del><ins>rows.</ins> Each row <del>group</del>is as wide as
the <del>table. Together, the</del>row groups <del>completely cover</del><ins>and as tall as a normal (single-row-spanning) cell in</ins>
the <del>table from top to bottom.</del><ins>row. As with columns,</ins> the <del>next to last layer contains</del><ins>background covers exactly</ins> the <del>rows.</del><ins>full
area of all cells that originate in</ins> the <del>rows also cover</del><ins>row, even if they span
outside</ins> the <del>whole table.</del><ins>row, but this difference in area does not affect
background image positioning.</ins>
<li>The topmost layer contains the cells themselves. As the figure
shows, although all rows contain the same number of cells, not every
cell may have specified content.
<ins>In the</ins> <a href="#separated-borders"><ins>separated borders model</ins></a>
<ins>(</ins><a href="tables.html#propdef-border-collapse" class="noxref"><span class="propinst-border-collapse"><ins>'border-collapse'</ins></span></a> <ins>is
'separate'), if the value of their</ins> <a href="tables.html#propdef-empty-cells" class="noxref"><span
class="propinst-empty-cells"><ins>'empty-cells'</ins></span></a> <ins>property is 'hide'</ins>
these "empty" cells are <del>transparent,</del><ins>transparent through the cell, row, row
group, column and column group backgrounds,</ins> letting <del>lower layers shine</del><ins>the table
background show</ins> through.
</ol>
<p><ins>A "missing cell" is a cell in the row/column grid that is not
occupied by an element or pseudo-element. Missing cells are rendered
as if an anonymous table-cell box occupied their position in the grid.</ins>
<div class="html-example">
<p>In the following example, the first row contains four <ins>non-empty</ins>
cells, but the second row contains <del>no cells,</del><ins>only one non-empty cell,</ins> and thus
the table background shines through, except where a cell from the
first row spans into this row. The following HTML code and style rules
<pre>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML <del>4.0//EN"></del><ins>4.01//EN"></ins>
<HTML>
<HEAD>
<ins><TITLE>Table example</TITLE></ins>
<STYLE type="text/css">
TABLE { background: #ff0; <del>border-collapse: collapse</del><ins>border: solid black;
empty-cells: hide</ins> }
<del>TD</del><ins>TR.top</ins> { background: <del>red;</del><ins>red }
TD {</ins> border: <del>double</del><ins>solid</ins> black }
</STYLE>
</HEAD>
<BODY>
<del><P></del><TABLE>
<del><TR></del><ins><TR CLASS="top"></ins>
<TD> 1
<TD rowspan="2"> 2
<TD> 3
<TD> 4
<del></TR> <TR><TD></TD></TR></del><ins><TR>
<TD> 5
<TD></ins>
</TABLE>
</BODY>
</HTML>
</pre>
<p>might be formatted as follows:
<div class="figure">
<p><img src="images/tbl-empty.png" alt="Table with three empty cells
in bottom row"><SPAN class="dlink"> <A name="img-tbl-empty" href="images/longdesc/tbl-empty-desc.html" title="Long description of example illustrating background calculation
">[D]</A></SPAN>
<p
ED1
class="caption">Table with <del>three</del>empty cells in the bottom row.
</div>
</div>
<p><ins>Note that if the table has 'border-collapse: separate', the
background of the area given by the</ins> <a href="tables.html#propdef-border-spacing" class="noxref"><span
class="propinst-border-spacing"><ins>'border-spacing'</ins></span></a> <ins>property is
always the background of the table element. See</ins> <a
href="#separated-borders"><ins>the separated borders model</ins></a><ins>.</ins>
<h3>17.5.2 <a name="width-layout">Table width algorithms:</a>
the <a href="tables.html#propdef-table-layout" class="noxref"><span class="propinst-table-layout">'table-layout'</span></a>
property</h3>
<p>CSS does not define an "optimal" layout for tables since, in many
cases, what is optimal is a matter of taste. CSS does define
constraints that user agents must respect when laying out a table.
User agents may use any algorithm they wish to do so, and are free to
prefer rendering speed over precision, except when the "fixed layout
algorithm" is selected.
<p><ins>Note that this section overrides the rules that apply to
calculating widths as described in</ins> <a
href="visudet.html#Computing_widths_and_margins"><ins>section 10.3</ins></a><ins>. In
particular, if the margins of a table are set to '0' and the width to
'auto', the table will not automatically size to fill its containing
block. However, once the calculated value of 'width' for the table is
found (using the algorithms given below or, when appropriate, some
other UA dependent algorithm) then the other parts of section 10.3 do
apply. Therefore a table</ins> <em><ins>can</ins></em> <ins>be centered using left and right
'auto' margins, for instance.</ins>
<p><ins>Future updates of CSS may introduce ways of making tables
automatically fit their containing blocks.</ins>
<div class="propdef">
<dl><dt>
<span class="index-def" title="'table-layout'"><a name="propdef-table-layout" class="propdef-title"><strong>'table-layout'</strong></a></span>
<dd>
<table class="propinfo" cellspacing=0 cellpadding=0>
<tr valign=baseline><td><em>Value:</em> <td>auto | fixed | <a href="cascade.html#value-def-inherit" class="noxref"><span class="value-inst-inherit">inherit</span></a>
<tr valign=baseline><td><em>Initial:</em> <td>auto
<tr valign=baseline><td><em>Applies to:</em> <td>'table' and 'inline-table' elements
<tr valign=baseline><td><em>Inherited:</em> <td>no
<tr valign=baseline><td><em>Percentages:</em> <td>N/A
<tr valign=baseline><td><em>Media:</em> <td><a href="media.html#visual-media-group" class="noxref">visual</a>
<tr valign=baseline><td><em><ins>Computed value:</ins></em><ins> </ins><td><ins>as specified</ins>
</table>
</dl>
</div>
<p>The <a href="tables.html#propdef-table-layout" class="noxref"><span class="propinst-table-layout">'table-layout'</span></a>
property controls the algorithm used to lay out the table cells, rows,
and columns. Values have the following meaning:
<dl>
<dt><strong>fixed</strong> <dd>Use the fixed table layout algorithm
<dt><strong>auto</strong> <dd>Use any automatic table layout
algorithm
</dl>
<p>The two algorithms are described below.
<h4><ins>17.5.2.1</ins> <a name="fixed-table-layout">Fixed table layout</a></h4>
<p>With this (fast) algorithm, the horizontal layout of the table does
not depend on the contents of the cells; it only depends on the
table's width, the width of the columns, and borders or cell spacing.
<p>The table's width may be specified explicitly with the <a href="visudet.html#propdef-width" class="noxref"><span
class="propinst-width">'width'</span></a> property. A value of 'auto' (for
both 'display: table' and 'display: inline-table') means use the <a
href="#auto-table-layout">automatic table layout</a> algorithm.
<ins>However, if the table is a block-level table ('display: table') in
normal flow, a UA may (but does not have to) use the algorithm of</ins> <a
href="visudet.html#blockwidth"><ins>10.3.3</ins></a> <ins>to compute a width and apply
fixed table layout even if the specified width is 'auto'.</ins>
<div class="example"><P style="display:none"><ins>Example(s):</ins></P>
<p><ins>If a UA supports fixed table layout when 'width' is 'auto', the
following will create a table that is 4em narrower than its containing
block:</ins>
<pre>
<ins>table { table-layout: fixed;
margin-left: 2em;
margin-right: 2em }</ins>
</pre>
</div>
<p>In the fixed table layout algorithm, the width of each column is
determined as follows:
<ol>
<li>A column element with a value other than 'auto' for the <a href="visudet.html#propdef-width" class="noxref"><span
class="propinst-width">'width'</span></a> property sets the width for
that column.
<li>Otherwise, a cell in the first row with a value other than
'auto' for the <a href="visudet.html#propdef-width" class="noxref"><span class="propinst-width">'width'</span></a> property
<del>sets</del><ins>determines</ins> the width for that column. If the cell spans more than
one column, the width is divided over the columns.
<li>Any remaining columns equally divide the remaining horizontal
table space (minus borders or cell spacing).
</ol>
<p>The width of the table is then the greater of the value of the
<a href="visudet.html#propdef-width" class="noxref"><span class="propinst-width">'width'</span></a> property for the table
element and the sum of the column widths (plus cell spacing or
borders). If the table is wider than the columns, the extra space
should be distributed over the columns.
<p><ins>If a subsequent row has more columns than the greater of the number
determined by the table-column elements and the number determined by
the first row, then
additional columns may not be rendered. CSS 2.1 does not define
the width of the columns and the table if they</ins> <em><ins>are</ins></em> <ins>rendered.
When using 'table-layout:
fixed', authors should not omit columns from the first row.</ins>
<p>In this manner, the user agent can begin to lay out the table once
the entire first row has been received. Cells in subsequent rows do
not affect column widths. Any cell that has content that overflows
uses the <a href="visufx.html#propdef-overflow" class="noxref"><span class="propinst-overflow">'overflow'</span></a> property to
determine whether to clip the overflow content.
<h4><ins>17.5.2.2</ins> <a name="auto-table-layout">Automatic table layout</a></h4>
<p>In this algorithm (which generally requires no more than two
passes), the table's width is given by the width of its columns (and
intervening <a href="#borders">borders</a>). This algorithm reflects
the behavior of several popular HTML user agents at the writing of
this specification. UAs are not required to implement this algorithm
to determine the table layout in the case that <a href="tables.html#propdef-table-layout" class="noxref"><span
class="propinst-table-layout">'table-layout'</span></a> is 'auto'; they
can use any other <del>algorithm.</del><ins>algorithm even if it results in different behavior.</ins>
<p><ins>Input to the automatic table layout must only include the width of
the containing block and the content of, and any CSS properties set
on, the table and any of its descendants.</ins>
<div class=note>
<p><em><strong><ins>Note.</ins></strong> <ins>This may be defined in more detail in
CSS3.</ins></em>
</div>
<p><em><ins>The remainder of this section is non-normative.</ins></em>
<p>This algorithm may be inefficient since it requires the user agent
to have access to all the content in the table before determining the
final layout and may demand more than one pass.
<p>Column widths are determined as follows:
<ol>
<li><p>Calculate the minimum content width (MCW) of each cell: the
formatted content may span any number of lines but may not overflow
the cell box. If the specified <a href="visudet.html#propdef-width" class="noxref"><span
class="propinst-width">'width'</span></a> (W) of the cell is greater
than MCW, W is the minimum cell width. A value of 'auto' means that
MCW is the minimum cell width.