Overview.bs

<pre class="metadata">
Title: CSS Multi-column Layout Module Level 1
Group: CSSWG
Shortname: css-multicol
Level: 1
Status: ED
Work Status: Testing
ED: http://dev.w3.org/csswg/css-multicol/
TR: http://www.w3.org/TR/css3-multicol/
Previous Version: http://www.w3.org/TR/2011/CR-css3-multicol-20110412/
Previous Version: http://www.w3.org/TR/2009/CR-css3-multicol-20091217/
Previous Version: http://www.w3.org/TR/2009/WD-css3-multicol-20090630/
Previous Version: http://www.w3.org/TR/2007/WD-css3-multicol-20070606/
Previous Version: http://www.w3.org/TR/2005/WD-css3-multicol-20051215/
Previous Version: http://www.w3.org/TR/2001/WD-css3-multicol-20010118/
Previous Version: http://www.w3.org/1999/06/WD-css3-multicol-19990623
Editor: Håkon Wium Lie, Opera Software, howcome@opera.com
Abstract: This specification describes multi-column layouts in CSS, a style sheet language for the web. Using functionality described in the specification, content can be flowed into multiple columns with a gap and a rule between them.
Link Defaults: css-color (property) color, css21 (property) max-height
</pre>

<style type="text/css">
.cols { width: 500px; height: 200px; background: #fff; position: relative; border: solid 5px blue; margin: 0.5em 2em 1em 0; font: bold 14px/19px Arial, sans-serif }
.cols p { padding: 3px; margin: 0 }
.col { position: absolute; left: 0px; top: 0; z-index: 6; width: 170px }
.gap { position: absolute; background: green; width: 5px; bottom: 0px; top: 0px; border: 10px solid yellow; border-top-width: 0; border-bottom-width: 0;  }
.rep { position: absolute; top: 45px; background: black; height: 110px; width: 100px;  color: white; z-index: 4 }

table.breaks { border-collapse: collapse; margin: 1em 0 }
table.breaks td, table.breaks th { border: thin solid black; padding: 0.1em 0.2em }

div.example:before { width: 9em }
</style>

<h2 id="introduction">
Introduction</h2>

	(This section is not normative.)

	This module describes multi-column layout in CSS. By using
	functionality described in this document, style sheets can declare
	that the content of an element is to be laid out in multiple
	columns.

	On the Web, tables have also been used to describe multi-column
	layouts. The main benefit of using CSS-based columns is flexibility;
	content can flow from one column to another, and the number of columns
	can vary depending on the size of the viewport. Removing presentation
	table markup from documents allows them to more easily be presented on
	various output devices including speech synthesizers and small mobile
	devices.

	Multi-column layouts are easy to describe in CSS. Here is a simple example:

	<div class=example>
		<pre>body { column-width: 12em }</pre>

		In this example, the <code class=html>body</code> element is
		set to have columns at least ''12em'' wide. The exact number of
		columns will depend on the available space.
	</div>

	The number of columns can also be set explicitly in the style sheet:

	<div class=example>
		<pre>body { column-count: 2 }</pre>

		In this case, the number of columns is fixed and the column widths
		will vary depending on the available width.
	</div>

	The shorthand 'columns' property can be used to set either,
	or both, properties in one declaration.

	<div class=example>
		In these examples, the number of columns, the width of columns, and
		both the number and width are set, respectively:

		<pre>
		body { columns: 2 }
		body { columns: 12em }
		body { columns: 2 12em }
		</pre>

		However, as described below, setting both the width and number of
		columns rarely makes sense.
	</div>

	Another group of properties introduced in this module describe
	gaps and rules between columns.

	<div class=example>
		<pre>
		body {
			column-gap: 1em;
			column-rule: thin solid black;
		}
		</pre>

		The first declaration in the example above sets the gap between two
		adjacent columns to be 1em. Column gaps are similar to padding areas.
		In the middle of the gap there will be a rule which is described by
		the 'column-rule' property.
	</div>

	The values of the 'column-rule' property are similar to those of
	the CSS border properties. Like 'border', 'column-rule' is a
	shorthand property.

	<div class=example>
		In this example, the shorthand 'column-rule' declaration from the
		above example has been expanded:

		<pre>
		body {
			column-gap: 1em;
			column-rule-width: thin;
			column-rule-style: solid;
			column-rule-color: black;
		}
		</pre>
	</div>

	The 'column-fill' and 'column-span' properties give style sheets a
	wider range of visual expressions in multi-column layouts.

	<div class=example>
		In this example, columns are set to be balanced, i.e., to have
		approximately the same length. Also, <code>h2</code> elements are set
		to span across all columns.

		<pre>
		div { column-fill: balance }
		h2 { column-span: all }
		</pre>
	</div>

	This specification introduces ten new properties, all of which
	are used in the examples above.

	To indicate where column breaks should (or should not) appear, new
	keyword values are introduced.

	<div class=example>
		In this example, <code>h1</code> elements will always have a column
		break before them, but the formatter will try to avoid column breaks
		inside and after the element.

		<pre>
		h1 {
			break-before: column;
			break-inside: avoid-column;
			break-after: avoid-column;
		}
		</pre>

		<!--
		The properties and values used in this example are formally defined in [!CSS3PAGE]].
		-->
	</div>

	If all column properties have their initial value, the layout of
	an element will be identical to a multi-column layout with only one
	column.

<h2 id="the-multi-column-model">
The multi-column model</h2>

	A <dfn lt="multi-column element|multicol element" export>multi-column element</dfn>
	(or <em>multicol element</em> for short)
	is an element whose 'column-width' or 'column-count'
	property is not ''column-width/auto'' and therefore acts as a container for
	multi-column layout.

	In the traditional CSS box model, the content of an element is
	flowed into the content box of the corresponding element. Multi-column
	layout introduces a new type of container between the content box and
	the content, namely the <dfn>column box</dfn> (or <em>column</em> for
	short). The content of a multicol element is flowed into its column
	boxes.

	Column boxes in a multi-column element are arranged
	into <em>rows</em>. Like table cells, the column boxes in a row are
	ordered in the inline direction of the multicol element. The
	<em>column width</em> is the length of the column box in the inline
	direction. The <em>column height</em> is the length of the column box
	in the block direction. All column boxes in a row have the same column width, and all
	column boxes in a row have the same column height. Within each row in the multi-column element,
	adjacent column boxes are separated by a <em>column gap</em>, which
	may contain a <em>column rule</em>. All column gaps in the same row
	are equal. All column rules in the same row are also equal, if they
	appear; column rules only appear between columns that both have
	content.

	In the simplest case a multicol element will contain only one row
	of columns, and the height of each column will be equivalent to the
	used height of the multi-column element's content box.

	<div class="example">
		Column gaps (yellow) and column rules (green) are shown in this
		sample rendition of a multi-column element with padding (blue). The
		blue and yellow is present for illustrational purposes only. In actual
		implementations these areas will be determined by the background.

		<div class=cols>
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs
			</div>

			<div class="col" style="left: 175px">
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
			</div>

			<div class="col" style="left: 350px">
				M nop qrst uv wx yz.<br>
				<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				Pqr stu vw xyz.
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>
	</div>

	If the multi-column element is paginated, the height of each row is
	constrained by the page and the content continues in a new row of
	column boxes on the next page; a column box never splits across pages.

	The same effect occurs when a <em>spanning element</em> divides the
	multi-column element: the columns before the spanning element are
	balanced and shortened to fit their content. Content after the
	spanning element then flows into a new row of column boxes.

	<div class="example">
		<div class=cols>
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			<br>
			<br>
			M nop qrst uv wx yz.<br>
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			def g hij klm nopqrs<br>
			tuv wxy z. Abc de fg<br>
			hi jklmno. Pqrstu vw<br>

			<div class="col" style="left: 175px">
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				<br>
				<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
			</div>

			<div class="col" style="left: 350px">
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				<br>
				<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz.
			</div>

			<div class=rep style="width: 490px; height: 20px; background: silver; font-size: 1.5em; padding: 5px">A spanning element</div>
			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>
	</div>

<!--
	To illustrate the effects of the various properties described in
	this specification, variations on a sample document will be used. Here
	is the source code of the sample document:

	<pre class="html">
	&lt;html>
	&lt;style type="text/css">
	div {
		column-width: 15em;
		column-gap: 2em;   /* shown in yellow */
		column-rule: 4px solid green;
		padding: 5px;      /* shown in blue */
	}
	p { margin: 0; padding: 0 }
	img { display: none }
	&lt;/style>
	&lt;body>
	&lt;div>
	&lt;p&gt;Ab cde fgh i jkl. Mno
	pqr stu vw xyz. A bc
	&lt;img src=...>
	def g hij
	...
	&lt;/div>
	&lt;/body>
	&lt;/html>
	</pre>

	The nonsensical text in the example is the English alphabet which
	shows how text flows from one column to another. To simplify the
	visualization, the textual content of the different examples vary
	slightly.
-->

	Column boxes are block container boxes. That
	is, column boxes behave like block-level, table cell, and inline-block
	boxes as per CSS 2.1, section 10.1, item 2 [[!CSS21]]. However, column
	boxes do not establish block container boxes for elements with ''position:
	fixed'' or ''position: absolute''.

	<div class=example>
		In this example, the width of the image is set with these rules:

		<pre class=css>
		img { display: block; width: 100% }
		</pre>

		Given that the width is calculated relative to the column box, the
		image will be as wide as the column box:

		<div class=cols>
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			<br>
			<br>
			<br>
			<br>
			<br>
			<br>
			def g hij klm nopqrs<br>
			tuv wxy z. Abc de fg<br>

			<div class="col" style="left: 175px">
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
			</div>

			<div class="col" style="left: 350px">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz.
			</div>

			<div class=rep style="width: 150px"></div>
			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>
	</div>

	Floats that appear inside multi-column layouts are positioned with
	regard to the column box where the float appears.

	<div class="example">
		In this example, this CSS fragment describes the presentation of the image:

		<pre class="css">
		img { display: block; float: right }
		</pre>

		<div class=cols>
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g<br>
				hij klm<br>
				nopq<br>
				rs tuv<br>
				wxy x<br>
				yz. Ab <br>
				cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc
			</div>

			<div class="col" style="left: 175px">
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
			</div>

			<div class="col" style="left: 350px">
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
			</div>

			<div class=rep style="left: 50px"></div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>

		The black box represents the image.
	</div>

	A multi-column element establishes a new block formatting context,
	as per CSS 2.1 section 9.4.1.

	<div class="example">
		A top margin set on the first child element of a multicol element will not collapse with the margins of the multicol element.
	</div>

	Nested multi-column elements are allowed, but there may be
	implementation-specific limits.


	Note: It is not possible to set properties/values on column boxes. For
	example, the background of a certain column box cannot be set and a
	column box has no concept of padding, margin or borders. Future specifications may add additional
	functionality. For example, columns of different widths and different
	backgrounds may be supported.

	Note: Multicol elements with column heights larger than the viewport may pose accessibility issues.


<h2 id="the-number-and-width-of-columns">
The number and width of columns</h2>

	Finding the number and width of columns is fundamental when laying
	out multi-column content. These properties are used to set the number
	and width of columns:

<!--When the block direction
is unconstrained and no column breaks are added through style sheets,
these two properties determine the outcome:-->

	<ul>
		<li>'column-count'
		<li>'column-width'
	</ul>

	A third property, 'columns', is a shorthand property which sets both
	'column-width' and 'column-count'.

	Other factors, such as explicit column breaks, content, and height
	constraints, may influence the actual number and width of columns.


<h3 id='cw'>
'column-width'</h3>

	<pre class=propdef>
	Name: column-width
	Value: auto | <<length>>
	Initial: auto
	Applies to: non-replaced block-level elements (except table elements), table cells, and inline-block elements
	Inherited: no
	Percentages: N/A
	Media: visual
	Computed value: the absolute length, zero or larger
	Animatable: as <<length>>
	</pre>

	This property describes the width of columns in multicol elements.

	<dl dfn-type=value dfn-for=column-width>
		<dt><dfn>auto</dfn>
		<dd>
			means that the column width will be determined by other properties
			(e.g., 'column-count', if it has a non-auto value).

		<dt><dfn><<length>></dfn>
		<dd>
			describes the optimal column width. The actual column width may be
			wider (to fill the available space), or narrower (only if the
			available space is smaller than the specified column width). Specified values
			must be greater than 0.
	</dl>

	<div class=example>
		For example, consider this style sheet:

		<pre>
		div {
			width: 100px;
			column-width: 45px;
			column-gap: 0;
			column-rule: none;
		}
		</pre>

		There is room for two 45px wide columns inside the 100px wide element. In
		order to fill the available space the actual column width will be
		increased to 50px.
	</div>

	<div class=example>
		Also, consider this style sheet:

		<pre>
		div {
			width: 40px;
			column-width: 45px;
			column-gap: 0;
			column-rule: none;
		}
		</pre>

		The available space is smaller than the specified column width and
		the actual column width will therefore be decreased.
	</div>

	To ensure that 'column-width' can be used with vertical text,
	column width means the length of the line boxes inside the columns.

	Note: The reason for making 'column-width' somewhat flexible
	is to achieve scalable designs that can fit many screen sizes. To set
	an exact column width, the column gap and the width of the multicol
	element (assuming horizontal text) must also be specified.


<h3 id='cc'>
'column-count'</h3>

	<pre class=propdef>
	Name: column-count
	Value: auto | <<integer>>
	Initial: auto
	Applies to: non-replaced block-level elements (except table elements), table cells, and inline-block elements
	Inherited: no
	Percentages: N/A
	Media: visual
	Computed value: specified value
	Animatable: as <<integer>>
	</pre>

	This property describes the number of columns of a multicol element.

	<dl dfn-type=value dfn-for=column-count>
		<dt><dfn>auto</dfn>
		<dd>
			means that the number of columns will be determined by other properties
			(e.g., 'column-width', if it has a non-auto value).

		<dt><dfn><<integer>></dfn>
		<dd>
			describes the optimal number of columns into which the content of
			the element will be flowed. Values must be greater than 0. If both
			'column-width' and 'column-count' have non-auto values, the integer
			value describes the maximum number of columns.
	</dl>


	<div class=example>
		Example:

		<pre>body { column-count: 3 }</pre>
	</div>


<h3 id="columns">
'columns'</h3>

	<pre class=propdef>
	Name: columns
	Value: <<'column-width'>> || <<'column-count'>>
	Initial: see individual properties
	Applies to: see individual properties
	Inherited: see individual properties
	Percentages: see individual properties
	Media: see individual properties
	Computed value: see individual properties
	Animatable: see individual properties
	</pre>

	This is a shorthand property for setting 'column-width' and
	'column-count'. Omitted values are set to their initial values.

	<div class="example">
		Here are some valid declarations using the 'columns' property:

		<pre>
		columns: 12em;      /* column-width: 12em; column-count: auto */
		columns: auto 12em; /* column-width: 12em; column-count: auto */
		columns: 2;         /* column-width: auto; column-count: 2 */
		columns: 2 auto;    /* column-width: auto; column-count: 2 */
		columns: auto;      /* column-width: auto; column-count: auto */
		columns: auto auto; /* column-width: auto; column-count: auto */
		</pre>
	</div>

<h3 id="pseudo-algorithm">
Pseudo-algorithm</h3>

	The pseudo-algorithm below determines the used values for
	'column-count' (N) and 'column-width' (W) when . There is one other variable
	in the pseudo-algorithm: U is the used width of the multi-column
	element.

	Note: The used width U of the multi-column element can depend on the element's contents,
	in which case it also depends on the computed values of the 'column-count' and 'column-width' properties.
	This specification does not define how U is calculated.
	Another module
	(probably the Basic Box Model [[CSS3BOX]] or the Intrinsic & Extrinsic Sizing Module [[CSS3-SIZING]])
	is expected to define this.

<!--
Two assumptions are being made by the pseudo-algorithm:

<ul>
<li>that the block direction is unconstrained
<li>that no column breaks are added through style sheets
</ul>
-->

	The <code>floor(X)</code> function returns the largest integer Y &le; X.

	<pre>
	(01)  if ((column-width = auto) and (column-count = auto)) then
	(02)      exit; /* not a multicol element */
	(03)  if column-width = auto then
	(04)      N := column-count
	(05)  else if column-count = auto then
	(06)      N := max(1,
	(07)        floor((U + column-gap)/(column-width + column-gap)))
	(08)  else
	(09)      N := min(column-count, max(1,
	(10)        floor((U + column-gap)/(column-width + column-gap))))
	</pre>

	And:

	<pre>
	(11)  W := max(0, ((U + column-gap)/N - column-gap))
	</pre>

	In paged media, user agents may perform this calculation on a
	per-page basis.

	The used value for 'column-count' is calculated without
	regard for explicit column breaks or constrained column heights,
	while the actual value takes these into consideration.

	<div class=example>
		In this example, the actual column-count is higher than the used column-count due to explicit column breaks:

		<pre>
		div { width: 40em; columns: 20em; column-gap: 0 }
		p { break-after: column }

		&lt;div>
			&lt;p>one
			&lt;p>two
			&lt;p>three
		&lt;/div>
		</pre>

		The computed column-count is auto, the used column-count is 2 and the actual column-count is 3.
	</div>

	<div class=example>
		The actual column-count may be lower than the used column-count. Consider this example:

		<pre>
		div {
			width: 80em;
			height: 10em;
			columns: 20em;
			column-gap: 0;
			column-fill: auto;
		}

		&lt;div>foo&lt;/div>
		</pre>

		The computed column-count is auto, the used column-count is 4, and the actual column-count is 1.
	</div>

<h3 id="stacking-context">
Stacking context</h3>

	All column boxes in a multi-column element are in the same stacking
	context and the drawing order of their contents is as specified in
	CSS 2.1. Column boxes do not establish new stacking contexts.

<h2 id="column-gaps-and-rules">
Column gaps and rules</h2>

	Column gaps and rules are placed between columns in the same
	multicol element. The length of the column gaps and column rules
	is equal to the column height. Column gaps take up space. That
	is, column gaps will push apart content in adjacent columns (within
	the same multicol element).

	A column rule is drawn in the middle of the column gap with the
	endpoints at opposing content edges of the multicol element. Column
	rules do not take up space. That is, the presence or thickness of a
	column rule will not alter the placement of anything else. If a column
	rule is wider than its gap, the adjacent column boxes will overlap the
	rule, and the rule may possibly extend outside the box of the multicol
	element. Column rules are painted in the inline content layer, but
	below all inline content inside the multicol element. Column rules are
	only drawn between two columns that both have content.

<h3 id='column-gap'>
'column-gap'</h3>

	<pre class=propdef>
	Name: column-gap
	Value: <<length>> | normal
	Initial: normal
	Applies to: <a>multicol elements</a>
	Inherited: no
	Percentages: N/A
	Media: visual
	Computed value: absolute length or ''normal''
	Animatable: as <<length>>
	</pre>

	<dl dfn-type=value dfn-for=column-gap>
		<dt><dfn><<length>></dfn>
		<dd>
			Specifies the gap between columns.
			If there is a column rule between columns,
			it will appear in the middle of the gap.

			The <<length>> cannot be negative.

		<dt><dfn>normal</dfn>
		<dd>
			Identical to <a value for="column-gap">&lt;length></a>,
			but with a UA-specified length.
			A value of ''1em'' is suggested.
	</dl>


<h3 id='crc'>
'column-rule-color'</h3>

	<pre class=propdef>
	Name: column-rule-color
	Value: <<color>>
	Initial: currentcolor
	Applies to: multicol elements
	Inherited: no
	Percentages: N/A
	Media: visual
	Computed value: same as the computed value of 'color' is computed
	Animatable: as <<color>>
	</pre>

	<dl>
		<dt><dfn value for=column-rule-color><<color>></dfn>
		<dd>
			Specifies the color of the column rule.
	</dl>


<h3 id='crs'>
'column-rule-style'</h3>

	<pre class=propdef>
	Name: column-rule-style
	Value: <<'border-style'>>
	Initial: none
	Applies to: multicol elements
	Inherited: no
	Percentages: N/A
	Media: visual
	Computed value: specified value
	Animatable: no
	</pre>

	The 'column-rule-style' property sets the style of the rule between columns of an element.
	The <<'border-style'>> values are interpreted as in the <a href="http://www.w3.org/TR/CSS2/tables.html#collapsing-borders">collapsing border model</a>.

	The ''border-style/none'' value forces the computed value of 'column-rule-width' to be ''0''.


<h3 id='crw'>
'column-rule-width'</h3>

	<pre class=propdef>
	Name: column-rule-width
	Value: <<'border-width'>>
	Initial: medium
	Applies to: multicol elements
	Inherited: no
	Percentages: N/A
	Media: visual
	Computed value: absolute length; ''0'' if the column rule style is ''none'' or ''hidden''
	Animatable: as <<length>>
	</pre>

	This property sets the width of the rule between columns.
	Negative values are not allowed.


<h3 id="column-rule">
'column-rule'</h3>

	<pre class=propdef>
	Name: column-rule
	Value: <<'column-rule-width'>> || <<'column-rule-style'>> || <<'column-rule-color'>>
	Initial: see individual properties
	Applies to: see individual properties
	Inherited: see individual properties
	Percentages: see individual properties
	Media: see individual properties
	Computed value: see individual properties
	Animatable: see individual properties
	</pre>

	This property is a shorthand for setting
	'column-rule-width', 'column-rule-style', and 'column-rule-color' at
	the same place in the style sheet. Omitted values are set to their
	initial values.

	<div class=example>
		In this example, the column rule and the column gap have the same
		width. Therefore, they will occupy exactly the same space.

		<pre>
		body {
			column-gap: 1em;
			column-rule-width: 1em;
			column-rule-style: solid;
			column-rule-color: black;
		}
		</pre>
	</div>


	<div class=example>
		If a tall image is moved to a column on the next page to find room
		for it, its natural column may be left empty. If so, the column is
		still considered to have content for the purpose of deciding if the
		column rule should be drawn.
	</div>

<h2 id="column-breaks">
Column breaks</h2>

	When content is laid out in multiple columns, the user agent must
	determine where column breaks are placed. The problem of breaking
	content into columns is similar to breaking content into pages, which
	is described in CSS 2.1, section 13.3.3 [[!CSS21]].

	Three new properties are introduced to allow column breaks to be
	described in the same properties as page breaks: 'break-before',
	'break-after', and 'break-inside'. These properties take the same
	values as 'page-break-before', 'page-break-after', and
	'page-break-inside'  [[!CSS21]]. In addition, some new keyword values
	are added.


<h3 id="break-before-break-after-break-inside">
'break-before', 'break-after', 'break-inside'</h3>

	<div noexport>
		<pre class="propdef">
		Name: break-before
		Value: auto | always | avoid | left | right | page | column | avoid-page | avoid-column
		Initial: auto
		Applies to: block-level elements
		Inherited: no
		Percentages: N/A
		Media: visual
		Computed value: specified value
		</pre>

		<pre class="propdef">
		Name: break-after
		Value: auto | always | avoid | left | right | page | column | avoid-page | avoid-column
		Initial: auto
		Applies to: block-level elements
		Inherited: no
		Percentages: N/A
		Media: visual
		Computed value: specified value
		</pre>

		<pre class="propdef">
		Name: break-inside
		Value: auto | avoid | avoid-page | avoid-column
		Initial: auto
		Applies to: block-level elements
		Inherited: no
		Percentages: N/A
		Media: visual
		Computed value: specified value
		</pre>
	</div>

	These properties describe page/column break behavior before/after/inside the generated box. These values are normatively defined in [[!CSS21]]:

	<dl dfn-type=value dfn-for="break-before, break-after, break-inside">
		<dt><dfn>auto</dfn>
		<dd>
			Neither force nor forbid a page/column break before (after, inside) the generated box.

		<dt><dfn>always</dfn>
		<dd>
			Always force a page break before (after) the generated box.

		<dt><dfn>avoid</dfn>
		<dd>
			Avoid a page/column break before (after, inside) the generated box.

		<dt><dfn for="break-before, break-after">left</dfn>
		<dd>
			Force one or two page breaks before (after) the generated box so that the next page is formatted as a left page.

		<dt><dfn for="break-before, break-after">right</dfn>
		<dd>
			Force one or two page breaks before (after) the generated box so that the next page is formatted as a right page.
	</dl>

	This specification adds the following new values:

	<dl dfn-type=value dfn-for="break-before, break-after, break-inside">
		<dt><dfn for="break-before, break-after">page</dfn>
		<dd>
			Always force a page break before (after) the generated box.

		<dt><dfn for="break-before, break-after">column</dfn>
		<dd>
			Always force a column break before (after) the generated box.

		<dt><dfn>avoid-page</dfn>
		<dd>
			Avoid a page break before (after, inside) the generated box.

		<dt><dfn>avoid-column</dfn>
		<dd>
			Avoid a column break before (after, inside) the generated box.
	</dl>

	When a page or column break splits a box, the box's margins,
	borders, and padding have no visual effect where the split occurs.
	However, the margin immediately after a forced page/column break will
	be preserved. A forced page/column break is a break that does not occur
	naturally.

	Note: In the future, new properties may describe alternate
	ways to handle margins, borders and padding around page/column breaks.

	<div class="example">
		In this example, forced column breaks appear before <code>h2</code>
		elements and after <code>img</code> elements:

		<pre>
		.multicol { column-width: 8em }
		.multicol h2 { break-before: column; margin-top: 2em }
		.multicol img { break-after: column }
		</pre>

		The top margin of <code>h2</code> elements will be preserved since the column break is forced.
	</div>

	<div class="example">
		In this example, the formatter will try avoid column breaks inside <code>p</code> elements:

		<pre>
		p { break-inside: avoid-column }
		</pre>
	</div>



<h2 id="spanning-columns">
Spanning columns</h2>

	The 'column-span' property makes it possible for an element to span across several columns.


<h3 id="column-span">
'column-span'</h3>

	<pre class="propdef">
	Name: column-span
	Value: none | all
	Initial: none
	Applies to: in-flow block-level elements
	Inherited: no
	Percentages: N/A
	Media: visual
	Computed value: specified value
	</pre>

	This property describes how many columns an element spans across. Values are:

	<dl dfn-type=value dfn-for=column-span>
		<dt><dfn>none</dfn>
		<dd>
			The element does not span multiple columns.

		<dt><dfn>all</dfn>
		<dd>
			The element spans across all columns of the nearest multicol
			ancestor in the same block formatting context. The element spans
			across all columns. Content in the normal flow that appears before the
			element is automatically balanced across all columns before the
			element appears. The element establishes a new block formatting
			context.
	</dl>

	An element that spans more than one column is called a
	<dfn export>spanning element</dfn> and the box it creates is called a <dfn export>spanner</dfn>.

	<!--
	This property has no effect on elements that do not fit entirely
	within the multicol element. Also, if a setting on this property pushes the
	element outside a multicol element, this property will have no effect.
	-->

	<div class="example">
		In this example, an <code>h2</code> element has been added to the
		sample document after the sixth sentence (i.e., after the word "jkl."). This styling applies:

		<pre class="css">
		h2 { column-span: all; background: silver }
		</pre>

		By setting 'column-span' to ''column-span/all'', all content that appear before
		the <code>h2</code> element is shown before the <code>h2</code>
		element.

		<div class=cols>
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			<br><br>
			M nop qrst uv wx yz.<br>
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			def g hij klm nopqrs<br>
			tuv wxy z. Abc de fg<br>
			hi jklmno. Pqrstu vw<br>

			<div class="col" style="left: 175px">
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				<br><br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
			</div>

			<div class="col" style="left: 350px">
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				<br><br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz.
			</div>

			<div class=rep style="width: 490px; height: 20px; background: silver; font-size: 1.5em; padding: 5px">An H2 element</div>
			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>
	</div>

	A spanning element takes up more space than the element would take
	up otherwise. When space is limited, it may be impossible to find room
	for the spanning element. In these cases, user agents may treat the
	element as if ''column-span/none'' had been specified on this property.

	<div class="example">
		In this example, the
		H2 element appears later in the content, and the height of the
		multicol element is constrained. Therefore, the H2 element appears in
		the overflow and there is not room to make the element spanning.
		As a result, the element appears as if 'column-span: none' was
		specified.

		<div class=cols style="height: 100px">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
			</div>

			<div class="col" style="left: 175px">
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs
			</div>

			<div class="col" style="left: 350px">
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
			</div>

			<div class="col" style="left: 525px">
				pqr stu vw xyz.
				<div class=rep style="width: 140px; height: 40px; background: silver; font-size: 1.5em; padding: 5px; margin: 0; position: static">An H2 element</div>
				A bc def g hij klm
			</div>

			<div class="col" style="left: 700px">
				nopqrs tuv wxy z.
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
			<div class=gap style="left: 500px"></div>
			<div class=gap style="left: 675px"></div>
		</div>
	</div>

	<div class="example">
		This example is similar to the previous example,
		except that the H2 element appears naturally in the last column.
		Still, there is not enough room to make the element spanning.

		<div class=cols style="height: 100px">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
			</div>

			<div class="col" style="left: 175px">
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs
			</div>

			<div class="col" style="left: 350px">
				tuv wxy z. Abc de fg<br>
				hi jklmno.
				<div class=rep style="width: 140px; height: 40px; background: silver; font-size: 1.5em; padding: 5px; margin: 0; position: static">An H2 element</div>
			</div>

			<div class="col" style="left: 525px">
				A bc def g hij klm<br>
				nop w rstu vw xyz.
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
			<div class=gap style="left: 500px"></div>
		</div>
	</div>

	<div class="example">
		In paged media spanning elements are honored on all pages.
		In this example, the first three paragraphs have column breaks after them.
		An spanning <code>H2</code> element appears after the fourth paragraph.
		This would appear on the first page:

		<div class=cols style="height: 80px; border-bottom: none">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz.
			</div>

			<div class="col" style="left: 175px">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z.
			</div>

			<div class="col" style="left: 350px">
				Ab cde fgh i jkl mno.<br>
				Pq rstu vwxyz.
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>

		This would appear on the second page:

		<div class=cols style="height: 200px; border-top: none">
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			<br><br>
			M nop qrst uv wx yz.<br>
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			def g hij klm nopqrs<br>
			tuv wxy z. Abc de fg<br>
			hi jklmno. Pqrstu vw<br>

			<div class="col" style="left: 175px">
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				<br><br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
			</div>

			<div class="col" style="left: 350px">
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				<br><br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz.
			</div>

			<div class=rep style="width: 490px; height: 20px; background: silver; font-size: 1.5em; padding: 5px">An H2 element</div>
			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>
	</div>

	<div class="example">
		Spanners create new block formatting contexts, but their margins
		can be changed by their surroundings. In this example, two spanners
		naturally end up at the top of a page. The top margin of the first
		spanner is truncated due to adjoining an unforced break. The margins
		between the two spanners collapse with each other. However, the bottom
		margin of the second spanner does not collapse with the top margin of
		the subsequent element.

		<pre>
		h2 {
			margin: 0.5em 0;
			column-span: all;
			background: silver
		}
		p { margin-top: 1em }
		</pre>

		<div class=cols style="border-top: none">
			<br><br><br><br>
			<br>
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			def g hij klm nopqrs<br>
			tuv wxy z. Abc de fg<br>
			hi jklmno. Pqrstu vw<br>

			<div class="col" style="left: 175px">
				<br><br><br><br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
			</div>

			<div class="col" style="left: 350px">
				<br><br><br><br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz.
			</div>

			<div class=rep style="width: 490px; top: 0; height: 20px; background: silver; font-size: 1.5em; padding: 5px">An H2 element</div>
			<div class=rep style="width: 490px; top: 40px; height: 20px; background: silver; font-size: 1.5em; padding: 5px">Another H2 element</div>
			<div class=gap style="top: 80px; left: 150px"></div>
			<div class=gap style="top: 80px; left: 325px"></div>
		</div>
	</div>



<h2 id="filling-columns">
Filling columns</h2>

	There are two strategies for filling columns: columns can either be
	balanced, or not. If columns are balanced, user agents should try to
	minimize variations in column height, while honoring forced breaks,
	'widows' and 'orphans', and other properties that may affect column
	heights. If columns are not balanced, they are filled sequentially;
	some columns may end up partially filled, or with no content at all.


<h3 id='cf'>
'column-fill'</h3>

	<pre class="propdef">
	Name: column-fill
	Value: auto | balance | balance-all
	Initial: balance
	Applies to: multicol elements
	Inherited: no
	Percentages: N/A
	Media: see below
	Computed value: specified value
	</pre>

	The values are:

	<dl dfn-type=value dfn-for=column-fill>
		<dt><dfn>balance</dfn>
		<dd>
			Balance content equally between columns, as far as possible.
			In paged media, only the last page is balanced.

		<dt><dfn>balance-all</dfn>
		<dd>
			Balance content equally between columns, as far as possible.
			In paged media, all pages are balanced.

		<dt><dfn>auto</dfn>
		<dd>
			fill columns sequentially
	</dl>

	<!--
	In continuous media, this property will only be consulted if the
	length of columns has been constrained. Otherwise, columns will
	automatically be balanced.
	-->

	In continuous media, this property does not have any effect in
	overflow columns.

	<!--
	In paged media, this property will only have
	effect on the last page the multicol element appears on.
	-->

	<div class=example>
		In this example, an article only has one short paragraph which fits
		on three lines. The three lines are displayed in three different
		columns due to column balancing.

		<pre>
		article { width: 60em; height: auto; columns: 4; column-fill: balance }
		</pre>

		<div class=cols style="width: 675px; height: 25px">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
			</div>

			<div class="col" style="left: 175px">
				pqr stu vw xyz. A bc
			</div>

			<div class="col" style="left: 350px">
				def g hij klm.
			</div>

			<div class="col" style="left: 525px">
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
			<div class=gap style="left: 500px"></div>
		</div>
	</div>

	<div class=example>
		In this example, column balancing is turned off:

		<pre>
		article { width: 60em; height: auto; columns: 4; column-fill: auto }
		</pre>

		As a result, the first column is filled with all content:

		<div class=cols style="width: 675px; height: 60px">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm.
			</div>

			<div class="col" style="left: 175px">
			</div>

			<div class="col" style="left: 350px">
			</div>

			<div class="col" style="left: 525px">
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
			<div class=gap style="left: 500px"></div>
		</div>
	</div>

	<div class=example>
		In this example, an article has two paragraphs: first a long one, then a shorter one. This code is applied:

		<pre>
		article { width: 60em; height: auto; columns: 4; column-fill: balance }
		p { break-after: column }
		</pre>

		The shortest column height possible contains five lines of text.
		After the column height has been established, columns are filled sequentially.
		As a result, the third column is as high as the first two columns,
		while the last column ends up being significantly shorter.

		<div class=cols style="width: 675px; height: 100px">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
			</div>

			<div class="col" style="left: 175px">
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm.
			</div>

			<div class="col" style="left: 350px">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
			</div>

			<div class="col" style="left: 525px">
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
			<div class=gap style="left: 500px"></div>
		</div>
	</div>

	<div class=example>
		<pre>
		article { width: 60em; height: auto; columns: 4; column-fill: balance }
		</pre>

		In this example, an article starts with an unbreakable figure which sets the column height.
		Subsequent content is filled sequentially into the remaining columns:

		<div class=cols style="width: 675px; height: 140px">
			<div class="col" style="">
			</div>

			<div class="col" style="left: 175px">
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			def g hij klm nopqrs<br>
			tuv wxy z. Abc de fg<br>
			hi jklmno. Pqrstu vw<br>
			x yz. Abc def ghi jkl.<br>
			M nop qrst uv wx yz.<br>
			</div>

			<div class="col" style="left: 350px">
			Ab cde fgh i jkl. Mno<br>
			pqr stu vw xyz. A bc<br>
			def g hij klm nopqrs<br>
			tuv wxy z. Abc de fg<br>
			hi jklmno.
			</div>

			<div class="col" style="left: 525px">
			</div>

			<div class=rep style="top: 0; width: 150px; height: 140px"></div>
			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
			<div class=gap style="left: 500px"></div>
		</div>
	</div>



<h2 id="overflow">
Overflow</h2>

<h3 id="overflow-inside-multicol-elements">
Overflow inside multicol elements</h3>

	<!--Floated or in-flow content that extends into column gaps (e.g.,
	long words or images) is clipped in the middle of the column gap.-->

	Floated or in-flow content that extends into column gaps or neighboring columns &mdash; e.g.,
	long words or images &mdash; is not clipped and may therefore cause overflow.

	<div class=example>
		In this example, the image is wider than the column:

		<div class=cols>
			Lorem ipsum dolor<br>sit amet. Nam at jus.
			<br><br><br><br><br><br><br>
			Sed imp er di et ris.<br>Cur abi tur et sapen.

			<div style="position: absolute; left: 175px; top: 0; z-index: 6;">
				Lorem ipsum dolor<br>sit amet. Nam at jus.<br>
				Sed imp er di et ris.<br>Cur abi tur et sapen.<br>
				Vivamus a metus.<br> Aenean at risus<br> pharetra ante
				luctu<br> feugiat quis enim.<br> Cum sociis natoque<br>
				penatibus et magni.
			</div>

			<div style="position: absolute; left: 350px; top: 0; z-index: 6;">
				Lorem ipsum dolor<br>sit amet. Nam at jus.<br>
				Sed imp er di et ris.<br>Cur abi tur et sapen.<br>
				Vivamus a metus.<br> Aenean at risus<br> pharetra ante
				luctu<br> feugiat quis enim.<br> Cum sociis natoque<br>
				penatibus et magni.
			</div>

			<div class=rep style="width: 183px"></div>
			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>
	</div>


<h3 id="pagination-and-overflow-outside-multicol">
Pagination and overflow outside multicol elements</h3>

	Content and column rules that extend outside column boxes at
	the edges of the multi-column element are clipped according to the
	'overflow' property.

	A multicol element can have more columns than it has room for due to:

	<ul>
		<li>
			a declaration that constrains the column height (e.g., using
			'height' or 'max-height'). In this case, additional column boxes
			are created in the inline direction

		<li>
			the size of the page. In this case, additional column boxes are
			moved to the next page(s).

		<li>
			explicit column breaks. In this case, additional column boxes are
			created in the inline direction for continuous media, and
			additional column boxes are moved to the next page(s) for paged
			media.
	</ul>

	Columns that appear outside the multicol element in continuous media
	are called <dfn>overflow columns</dfn>.

	<div class="example">
		In this example, the height of the multi-column element has been
		constrained to a maximum height. Also, the style sheet specifies that
		overflowing content should be visible:

		<pre>
		div {
			max-height: 5em;
			overflow: visible;
		}
		</pre>

		As a result, the number of columns is increased.

		<div class=cols style="height: 100px">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
			</div>

			<div class="col" style="left: 175px">
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs
			</div>

			<div class="col" style="left: 350px">
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
			</div>

			<div class="col" style="left: 525px">
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
			<div class=gap style="left: 500px"></div>
		</div>
	</div>

	<div class="example">
		In paged media, the overflow content goes into column on subsequent pages.
		Given the same content as in the previous example
		and a page box that only has room for five lines of formatted text,
		this would appear on the first page:

		<div class=cols style="height: 100px; border-bottom: none">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
			</div>

			<div class="col" style="left: 175px">
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs
			</div>

			<div class="col" style="left: 350px">
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
				x yz. Abc def ghi jkl.<br>
				M nop qrst uv wx yz.<br>
				Ab cde fgh i jkl. Mno<br>
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>

		Assuming column balancing, this would appear on the second page:

		<div class=cols style="height: 45px; border-top: none">
			<div class="col" style="">
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
			</div>

			<div class="col" style="left: 175px">
				tuv wxy z. Abc de fg<br>
				hi jklmno. Pqrstu vw<br>
			</div>

			<div class="col" style="left: 350px">
				x yz. Abc def ghi jkl.<br>
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>
	</div>

	<div class="example">
		In this example, explicit column breaks are generated after paragraphs:

		<pre>
		p {
			break-after: column;
		}
		</pre>

		As a result, the number of columns increases and the extra columns
		are added in the inline direction:

		<div class=cols style="height: 100px">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz.
			</div>

			<div class="col" style="left: 175px">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxyz. Abc defghi<br>
				jklmno pqrstu vwxyz.
			</div>

			<div class="col" style="left: 350px">
				Ab cde fgh i jkl mno.<br>
			</div>

			<div class="col" style="left: 525px">
				Pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxy z.
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
			<div class=gap style="left: 500px"></div>
		</div>
	</div>

	<div class="example">
		In paged media, extra columns are shown on the next page.
		Given the same code as the previous example,
		the last paragraph appears on the second page.
		This would appear on the first page:

		<div class=cols style="height: 100px; border-bottom: none">
			<div class="col" style="">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz.
			</div>

			<div class="col" style="left: 175px">
				Ab cde fgh i jkl. Mno<br>
				pqr stu vw xyz. A bc<br>
				def g hij klm nopqrs<br>
				tuv wxyz. Abc defghi<br>
				jklmno pqrstu vwxyz.
			</div>

			<div class="col" style="left: 350px">
				Ab cde fgh i jkl mno.<br>
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>

		This would appear on the second page:

		<div class=cols style="height: 23px; border-top: none">
			<div class="col" style="">
				Pqr stu vw xyz. A bc
			</div>

			<div class="col" style="left: 175px">
				def g hij klm nopqrs
			</div>

			<div class="col" style="left: 350px">
				tuv wxy z.
			</div>

			<div class=gap style="left: 150px"></div>
			<div class=gap style="left: 325px"></div>
		</div>

		Due to column balancing, the last paragraph is split across three columns.
	</div>

<h2 class=no-num id=acknowledgments>
Acknowledgments</h2>

	This document is based on several older proposals and comments on older proposals.
	Contributors include:

	Alex Mogilevsky,
	Andy Clarke,
	Anton Prowse,
	Bert Bos,
	Björn Höhrmann,
	Cédric Savarese,
	Chris Lilley,
	Chris Wilson,
	Daniel Glazman and
	Dave Raggett,
	David Hyatt,
	David Singer,
	David Woolley,
	Elika Etemad,
	Giovanni Campagna,
	Ian Hickson.
	Joost de Valk,
	Kevin Lawver,
	L. David Baron,
	Markus Mielke,
	Melinda Grant,
	Michael Day,
	Øyvind Stenhaug,
	Peter Linss,
	Peter-Paul Koch,
	Robert O'Callahan,
	Robert Stevahn,
	Sergey Genkin,
	Shelby Moore,
	Steve Zilles,
	Sylvain Galineau,
	Tantek Çelik,
	Till Halbach,