Overview.bs

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<pre class='metadata'>
Title: CSS Basic User Interface Module Level 4
ED: https://drafts.csswg.org/css-ui-4/
Status Text: This specification will include and extend <cite>CSS Basic User Interface Module Level&nbsp;3.</cite> [[CSS-UI-3]]
TR: https://www.w3.org/TR/css-ui-4/
Previous Version: https://www.w3.org/TR/2021/WD-css-ui-4-20210316/
Previous Version: https://www.w3.org/TR/2020/WD-css-ui-4-20200124/
Previous Version: https://www.w3.org/TR/2020/WD-css-ui-4-20200102/
Previous Version: https://www.w3.org/TR/2017/WD-css-ui-4-20171222/
Previous Version: https://www.w3.org/TR/2015/WD-css-ui-4-20150922/
Shortname: css-ui
Level: 4
Status: ED
Group: csswg
Work Status: Revising
Editor: Florian Rivoal, On behalf of Bloomberg, https://florian.rivoal.net/, w3cid 43241
Editor: Tab Atkins-Bittner, Google, http://xanthir.com/contact/, w3cid 42199
Abstract: This specification describes user interface related
	properties and values to style HTML and XML (including XHTML).
	It includes and extends user interface related features
	from the properties and values of previous CSS levels.
	It uses various properties and values
	to style basic user interface elements in a document.
At risk: Applicability of 'user-select' to ''::before'' and ''::after''
Can I Use URL: https://drafts.csswg.org/css-ui-3/
Can I Use URL: http://drafts.csswg.org/css-ui-3/
Can I Use URL: https://drafts.csswg.org/css-ui/
Can I Use URL: http://drafts.csswg.org/css-ui/
Can I Use URL: https://www.w3.org/TR/css-ui-3/
Can I Use URL: http://www.w3.org/TR/css-ui-3/
Can I Use URL: https://www.w3.org/TR/css3-ui/
Can I Use URL: http://www.w3.org/TR/css3-ui/
Can I Use URL: https://drafts.csswg.org/css-ui-4/
Can I Use URL: http://drafts.csswg.org/css-ui-4/
Can I Use URL: https://www.w3.org/TR/css-ui-4/
Can I Use URL: http://www.w3.org/TR/css-ui-4/
Ignore Can I Use URL Failure: https://drafts.csswg.org/css-ui-3/
Ignore Can I Use URL Failure: http://drafts.csswg.org/css-ui-3/
Ignore Can I Use URL Failure: https://drafts.csswg.org/css-ui/
Ignore Can I Use URL Failure: http://drafts.csswg.org/css-ui/
Ignore Can I Use URL Failure: https://www.w3.org/TR/css-ui-3/
Ignore Can I Use URL Failure: http://www.w3.org/TR/css-ui-3/
Ignore Can I Use URL Failure: https://www.w3.org/TR/css3-ui/
Ignore Can I Use URL Failure: http://www.w3.org/TR/css3-ui/
Ignore Can I Use URL Failure: https://drafts.csswg.org/css-ui-4/
Ignore Can I Use URL Failure: http://drafts.csswg.org/css-ui-4/
Ignore Can I Use URL Failure: https://www.w3.org/TR/css-ui-4/
Ignore Can I Use URL Failure: http://www.w3.org/TR/css-ui-4/
</pre>

<pre class=link-defaults>
spec:css-writing-modes-4; type:dfn; text:start
spec:css-writing-modes-4; type:dfn; text:end
spec:css2; type:property; text:min-width
spec:css2; type:property; text:max-width
spec:css2; type:property; text:min-height
spec:css2; type:property; text:max-height
spec:css2; type:property; text:bottom
spec:css2; type:property; text:top
spec:css2; type:property; text:right
spec:css2; type:property; text:visibility
spec:css2; type:property; text:z-index
spec:css-overflow-3; type:dfn; text:ink overflow area
spec:css-pseudo-4; type:selector; text:::before
spec:css-pseudo-4; type:selector; text:::after
spec:css-pseudo-4; type:selector; text:::first-line
spec:css-pseudo-4; type:selector; text:::first-letter
spec:selectors-4; type:selector; text::checked
spec:css-display-3; type:property; text:display
spec:css-color-4; type:value; text:currentcolor
spec:css-overflow-3; type:property; text:overflow
spec:css-sizing-3; type:property; text:box-sizing
spec:css-backgrounds-3; type:property; text:background-image
spec:css-backgrounds-3; type:property; text:border-width
spec:css-overflow-4; type:property; text:text-overflow
spec:selectors-4; type:selector; text::enabled
spec:selectors-4; type:selector; text::disabled
spec:css-color-4; type:property; text:color
spec:selectors-4; type:selector; text::focus
spec:selectors-4; type:selector; text::focus-visible
spec:css-backgrounds-3; type:property; text:border-radius
spec:css-backgrounds-3; type:property; text:border-color
spec:css-backgrounds-3; type:property; text:border-top-color
spec:css-backgrounds-3; type:property; text:border-right-color
spec:css-backgrounds-3; type:property; text:border-bottom-color
spec:css-backgrounds-3; type:property; text:border-left-color
</pre>
<pre class=anchors>
urlPrefix: https://html.spec.whatwg.org/multipage/; spec:HTML
	text:password; type:attr-value; for:input/type; url: input.html#attr-input-type-password-keyword
</pre>

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

	This module describes CSS properties which enable authors
	to style user interface related properties and values.

	<a href="https://www.w3.org/TR/REC-CSS1#anchor-pseudo-classes">Section 2.1 of CSS1</a> [[CSS1]]
	and <a href="https://www.w3.org/TR/CSS2/ui.html">Chapter 18 of CSS2</a> [[CSS21]]
	introduced several user interface related properties and values.
	<a href="https://www.w3.org/TR/2000/WD-css3-userint-20000216">User Interface for CSS3 (16 February 2000)</a> introduced several new user interface related features.

	[[CSS-UI-3]] was later introduced to incorporate, extend, and supersede these.
	This specification continues this work, and in turn replaces [[CSS-UI-3]].


<h3 id="purpose">
Purpose</h3>

	The purpose of this specification is to achieve the following objectives:

	<ul>
		<li>
			Extend the user interface features in [[CSS21]] and [[CSS-UI-3]]

		<li>
			Provide additional CSS mechanisms to augment or replace other
			dynamic presentation related features in HTML.

		<li>
			Introduce directional navigation properties to assist in the construction of
			user interfaces which make use of a directional navigation model.
	</ul>

<h2 id="interaction">Module Interactions</h2>

	This document defines new features not present in earlier specifications.
	In addition, it replaces and supersedes [[!CSS-UI-3]],
	which itself replaced and superseded the following:

	<ul>
		<li>
			<a href="https://www.w3.org/TR/CSS21/ui.html#cursor-props">Section 18.1</a>,
			<a href="https://www.w3.org/TR/CSS21/ui.html#dynamic-outlines">section 18.4</a>,
			and Information on the stacking of outlines defined in
			<a href="https://www.w3.org/TR/CSS21/zindex.html">Appendix E</a>
			of Cascading Style Sheets, level 2, revision 1 [[CSS21]]

		<li>
			<a href="https://www.w3.org/TR/2000/WD-css3-userint-20000216">User Interface for CSS3 (16 February 2000)</a> [[CSS-UI-3]]
	</ul>

	Note:
	<span id="box-model"></span>
	<span id="box-sizing"></span>
	<span id="propdef-box-sizing"></span>
	<span id="valdef-box-sizing-content-box"></span>
	<span id="valdef-box-sizing-border-box"></span>
	<span id="min-inner-width"></span>
	<span id="max-inner-width"></span>
	<span id="min-inner-height"></span>
	<span id="max-inner-height"></span>
	<span id="example-d824f1dc"></span>
	<span id="box-sizing-example"></span>
	The 'box-sizing' property was previously defined in this section of the specification,
	but has been moved to [[CSS-SIZING-3#box-sizing]].

	Note:
	<span id="text-overflow" caniuse=text-overflow></span>
	<span id="propdef-text-overflow"></span>
	<span id="overflow-clip"></span>
	<span id="overflow-ellipsis"></span>
	<span id="overflow-string"></span>
	<span id="funcdef-text-overflow-fade"></span>
	<span id="issue-ebe65138"></span>
	<span id="issue-2e22b1d9"></span>
	<span id="issue-948cb1ee"></span>
	<span id="valdef-text-overflow-fade"></span>
	<span id="example-160d0058"></span>
	<span id="bidi-ellipsis"></span>
	<span id="ellipsing-details"></span>
	<span id="ellipsis-interaction"></span>
	<span id="example-44082941"></span>
	<span id="text-overflow-examples"></span>
	<span id="issue-4b5212a2"></span>
	<span id="ellipsis-scrolling"></span>
	<span id="example-45d2531f"></span>
	<span id="example-347bbb66"></span>
	The 'text-overflow' property was previously defined in this section of the specification,
	but has been moved to [[CSS-OVERFLOW-3#text-overflow]].

<h3 id="values">
Value Definitions</h3>

	This specification follows the <a href="https://www.w3.org/TR/CSS2/about.html#property-defs">CSS property definition conventions</a> from [[!CSS21]]
	using the <a href="https://www.w3.org/TR/css-values-3/#value-defs">value definition syntax</a> from [[!CSS-VALUES-3]].
	Value types not defined in this specification are defined in CSS Values &amp; Units [[!CSS-VALUES-3]].
	Combination with other CSS modules may expand the definitions of these value types.

	In addition to the property-specific values listed in their definitions,
	all properties defined in this specification
	also accept the <a>CSS-wide keywords</a> as their property value.
	For readability they have not been repeated explicitly.

<h2 id="outline-props" caniuse="outline">
Outline properties</h2>

	At times, style sheet authors may want to create outlines around
	visual objects such as buttons, active form fields, image maps, etc.,
	to make them stand out. Outlines differ from borders in the following
	ways:

	<ol>
		<li>Outlines do not take up space.
		<li>Outlines contribute to the [=ink overflow area=] of an element.
		<li>Outlines may be non-rectangular.
		<li>UAs often render outlines on elements in the '':focus-visible'' state.
	</ol>

	The outline properties control the style of these dynamic outlines.

	The stacking of the rendering of these outlines is explicitly left up to implementations
	to provide a better user experience per platform.
	This supersedes the stacking of outlines as defined in <a href="https://www.w3.org/TR/CSS21/zindex.html">Appendix E of CSS 2.1</a> [[CSS21]].

	<strong class="advisement">
		Keyboard users,
		 in particular people with disabilities
		 who may not be able to interact with the page in any other fashion,
		 depend on the outline being visible
		 on elements in the '':focus-visible'' state,
		 thus authors must not make the outline invisible on such elements
		 without making sure an alternative highlighting mechanism is provided.
	</strong>

	The rendering of applying transforms to outlines is left explicitly undefined.


<h3 id="outline">Outlines Shorthand: the 'outline' property</h3>

	<pre class="propdef shorthand">
	Name: outline
	Value: [ <<'outline-width'>> || <<'outline-style'>> || <<'outline-color'>> ]
	Applies to: all elements
	Inherited: no
	Percentages: N/A
	</pre>

	The 'outline' property is a shorthand property
	and sets all three of 'outline-style',
	'outline-width',
	and 'outline-color'.
	In the ambiguous case where
	a lone ''outline-style/auto'' value is specified,
	or if ''outline-style/auto'' is specified together with an <<'outline-width'>> value,
	but without an explicit <<'outline-style'>> or <<'outline-color'>> value,
	both 'outline-style' and 'outline-color' are set to ''outine-style/auto''.

	Note: The shorthand purposefully omits the 'outline-offset' property,
	which determines the position rather than the appearance of the outline,
	so that it can cascade independently,
	as well as for backwards compatibility reasons.

	The outline created with the outline properties is drawn "over" a box,
	i.e., the outline is always on top
	and doesn't influence the position or size of the box,
	or of any other boxes.
	Therefore, displaying or suppressing outlines does not cause reflow.

	Outlines may be non-rectangular.
	For example, if the element is broken across several lines,
	the outline should be an outline or minimum set of outlines
	that encloses all the element's boxes.

	Each part of the outline should be fully connected
	rather than open on some sides
	(as borders on inline elements are when lines are broken).

	The parts of the outline are not required to be rectangular.
	To the extent that the outline follows the <a>border edge</a>,
	it should follow the 'border-radius' curve.

	The position of the outline may be affected by descendant boxes.

	The dimensions of the drawn outline contribute to the
	[=ink overflow area=] of an element.

	User agents should use an algorithm for determining
	the outline that encloses a region appropriate
	for conveying the concept of focus to the user.

	Note: This specification does not define the exact position or shape of the outline, but it is typically drawn immediately outside the border box.

	Note: The outline is the same on all sides.
	In contrast to borders,
	there are no ''outline-top'', ''outline-left'', etc. properties.

	This specification does not define how multiple overlapping outlines are drawn
	or how outlines are drawn for boxes that are partially obscured behind other elements.

	<div class="example">
		Here's an example of drawing a thick outline around a BUTTON element:
		<pre><code class="lang-css">
		button { outline: thick solid }
		</code></pre>
	</div>

	Graphical user interfaces may use outlines around elements
	to tell the user which element on the page has the focus.
	These outlines are shown in addition to any borders,
	and switching outlines on and off should not cause the document to reflow.
	The focus is the subject of user interaction in a document
	(e.g. for entering text or selecting a button).

	<div class="example">
		For example, to draw a thick black line around an element when it has the focus,
		and a thick red line when it is active,
		the following rules can be used:
		<pre><code class="lang-css">
		:focus  { outline: thick solid black }
		:active { outline: thick solid red }
		</code></pre>
	</div>

	Note: Since the outline does not affect formatting
	(i.e., no space is left for it in the box model),
	it may well overlap other elements on the page.


<h3 id="outline-width">
Outline Thickness: the 'outline-width' property</h3>

	<pre class="propdef">
	Name: outline-width
	Value: <<line-width>>
	Initial: medium
	Applies to: all elements
	Inherited: no
	Percentages: N/A
	Computed value: absolute length, [=snapped as a border width=]; ''0'' if the outline style is ''border-style/none''.
	Animation type: by computed value
	</pre>

	The 'outline-width' property accepts
	the same values as 'border-width'
	([[css-backgrounds-3#border-width]]),
	with the same meaning.


<h3 id="outline-style">
Outline Patterns: the 'outline-style' property</h3>

	<pre class="propdef">
	Name: outline-style
	Value: auto | <<outline-line-style>>
	Initial: none
	Applies to: all elements
	Inherited: no
	Percentages: N/A
	Computed value: specified keyword
	Animation type: by computed value
	</pre>

	<dfn><<outline-line-style>></dfn> accepts
	the same values as <<line-style>>
	([[css-backgrounds-3#border-style]])
	with the same meaning,
	except that
	<span class=css>hidden</span> is not a legal outline style.
	In addition,
	the 'outline-style' property
	accepts the value ''outline-style/auto''.

	The ''outline-style/auto'' value permits the user agent
	to render a custom outline style,
	typically a style which is either a user interface default for the platform,
	or perhaps a style that is richer
	than can be described in detail in CSS,
	e.g. a rounded edge outline with semi-translucent outer pixels
	that appears to glow.
	User agents may enable authors to influence the rendering of
	''outline-style/auto'' style outlines
	via the 'outline-color' property,
	but this specification does not define how the rendering is impacted (if at all).
	The 'outline-width' property is ignored when 'outline-style' is ''outline-style/auto''.
	User agents may treat ''outline-style/auto'' as
	''outline-style/solid''.

	<wpt>
		css/css-ui/outline-auto-width-001.html
	</wpt>


<h3 id="outline-color">
Outline Colors: the 'outline-color' property</h3>

	<pre class="propdef">
	Name: outline-color
	Value: auto | [ <<color>> | <<image-1D>> ]
	Initial: auto
	Applies to: all elements
	Inherited: no
	Percentages: N/A
	Computed value: see below
	Animation type: by computed value
	</pre>

	The 'outline-color' property
	accepts all values of <'border-color'>,
	as well as the following keywords:

	<dl dfn-type=value dfn-for=outline-color>
		<dt><dfn>auto</dfn>
		<dd>
			When 'outline-style' is ''outline-style/auto'',
			''outline-color: auto'' computes to ''outline-style/auto''
			and represents the [=accent color=].

			Otherwise,
			''outline-color: auto'' computes to ''currentColor''.
	</dl>

	See [[css-color-4#resolving-color-values]]
	for the computed value of <<color>> values,
	and [[css-images-4#stripes]]
	for <<image-1D>> values.

	<div id=valdef-outline-color-invert class=note>
		Earlier versions of this specification had an additional <code>invert</code> value,
		performing a color inversion on the pixels on the screen.
		This is no longer supported,
		and was removed for lack of implementations
		(and of intent to implement)
		in modern user agents.
		See [[css-ui-3#outline-color]] for details.
	</div>


<h3 id="outline-offset">
Offsetting the Outline: the 'outline-offset' property</h3>

	By default, the outline is drawn starting just outside the <a>border edge</a>.
	However, it is possible to offset the outline and draw it beyond the <a>border edge</a>.

	<pre class="propdef">
	Name: outline-offset
	Value: <<length>>
	Initial: 0
	Applies to: all elements
	Inherited: no
	Percentages: N/A
	Computed value: absolute length
	Animation Type: by computed value
	</pre>

	If the computed value of 'outline-offset'
	is anything other than 0,
	then the outline is outset from the <a>border edge</a> by that amount.

	<div class="example">
		For example,
		to leave 2 pixels of space between a focus outline
		and the element that has the focus or is active,
		the following rule can be used:
		<pre><code class="lang-css">
		:focus,:active  { outline-offset: 2px }
		</code></pre>
	</div>

	<p id=negative-offset>Negative values must cause the outline
	to shrink into the border box.
	Both the height and the width of the outside of the shape
	drawn by the outline should not become smaller
	than twice the computed value of the 'outline-width' property
	to make sure that an outline can be rendered
	even with large negative values.
	User agents should apply this constraint
	independently in each dimension.
	If the outline is drawn as multiple disconnected shapes,
	this constraint applies to each shape separately.


<h2 id="resizing">
<!--maintaining old anchors back from when text-overflow was defined here--><span id="resizing-and-overflow"></span>
Resizing</h2>

	CSS2.1 provides a mechanism for controlling the appearance of a scrolling mechanism
	(e.g. scrollbars)
	on block container elements.
	This specification adds a mechanism to that for controlling
	user resizability of elements as well as the ability to specify text overflow behavior.


<h3 id="resize" caniuse="css-resize">
Resizing Boxes: the 'resize' property</h3>

	The 'resize' property allows the author
	to specify whether or not an element is resizable by the user,
	and if so, along which axis/axes.

	<pre class="propdef">
	Name: resize
	Value: none | both | horizontal | vertical | block | inline
	Initial: none
	Applies to: elements that are <a>scroll containers</a>
	 and optionally replaced elements such as images, videos, and iframes
	Inherited: no
	Percentages: N/A
	Computed value: specified keyword
	Animation type: discrete
	</pre>

	<dl>
		<dt>none
		<dd>
			The UA does not present a resizing mechanism on the element,
			and the user is given no direct manipulation mechanism to resize the element.

		<dt>both
		<dd>
			The UA presents a bidirectional resizing mechanism
			to allow the user to adjust both the height and the width of the element.

		<dt>horizontal
		<dd>
			The UA presents a unidirectional horizontal resizing mechanism
			to allow the user to adjust only the width of the element.

		<dt>vertical
		<dd>
			The UA presents a unidirectional vertical resizing mechanism
			to allow the user to adjust only the height of the element.

		<dt>block
		<dd>
			The UA presents a unidirectional [=block-axis=] resizing mechanism
			to allow the user to adjust only the [=block size=] of the element.

		<dt>inline
		<dd>
			The UA presents a unidirectional [=inline-axis=] resizing mechanism
			to allow the user to adjust only the [=inline size=] of the element.
	</dl>

	Currently it is possible to control the appearance of the scrolling mechanism (if any)
	on an element using the 'overflow' property
	(e.g. <code class="lang-css">overflow: scroll</code> vs. <code class="lang-css">overflow: hidden</code> etc.).
	The purpose of the 'resize' property
	is to allow control over the appearance and function of the resizing mechanism
	(e.g. a resize box or widget) on the element.

	Note: The resizing mechanism is NOT the same as the scrolling mechanism,
	nor is it related to any UA mechanism for zooming.
	The scrolling mechanism allows the user
	to determine which portion of the contents of an element is shown.
	The resizing mechanism allows the user
	to determine the size of the element.

	The 'resize' property applies to elements
	that are <a>scroll containers</a>.
	UAs may also apply it,
	regardless of the value of the 'overflow' property,
	to:

	<ul>
		<li>
			Replaced elements representing images or videos,
			such as <{img}>, <{video}>, <{picture}>, <{svg}>, <{object}>, or <{canvas}>.

		<li>
			The <{iframe}> element.
	</ul>


	The effect of the 'resize' property on generated content is undefined.
	Implementations should not apply the 'resize' property to generated content.

	Note: the 'resize' property may apply to generated content in the future
	if there is implementation of <a href="https://drafts.csswg.org/css-pseudo/#CSSPseudoElement-interface">Interface CSSPseudoElement</a>.

	When an element is resized by the user,
	the user agent sets
	the 'width' and 'height' properties
	to px unit length values of the size indicated by the user,
	in the element’s <a href="https://www.w3.org/TR/css-style-attr/#style-attribute">style attribute</a> DOM,
	replacing existing property declaration(s), if any,
	without ''!important'', if any.

	If an element is resized in only one dimension,
	only the corresponding property is set, not both.

	The precise direction of resizing
	(i.e. altering the top-left of the element or altering the bottom-right)
	may depend on a number of CSS layout factors
	including whether the element is absolutely positioned,
	whether it is positioned using the 'right'
	and 'bottom' properties,
	whether the language of the element is right-to-left etc.
	The UA should consider the direction of resizing
	(as determined by CSS layout),
	as well as platform conventions and constraints when deciding
	how to convey the resizing mechanism to the user.

	The user agent must allow the user to resize the element
	with no other constraints than what is imposed by
	'min-width', 'max-width', 'min-height', and 'max-height'.

	Note: There may be situations in which user attempts to resize an element
	appear to be overridden or ignored, e.g. because of ''!important'' cascading declarations that supersede
	that element’s <a href="https://www.w3.org/TR/css-style-attr/#style-attribute">style attribute</a>
	'width' and 'height' properties in the DOM.

	Changes to the computed value of an element's 'resize' property
	do not reset changes to the <a href="https://www.w3.org/TR/css-style-attr/#style-attribute">style attribute</a> made due to
	user resizing of that element.

	<div class="example">
		For example,
		to make iframes scrollable <em>and</em> resizable,
		the following rule can be used:
		<pre><code class="lang-css">
		iframe,object[type^="text/"],
		object[type$="+xml"],object[type="application/xml"]
		{
		  overflow:auto;
		  resize:both;
		}
		</code></pre>
	</div>


<h2 id="pointing-keyboard">
Pointing Devices and Keyboards</h2>

<h3 id="pointer-interaction">
Pointer interaction</h3>

<h4 id="cursor" caniuse="css3-cursors">
Styling the Cursor: the 'cursor' property</h4>

	<pre class="propdef">
	Name: cursor
	Value: [ [ <<url>> | <<url-set>> ] [&lt;x&gt; &lt;y&gt;]? ]#? <br>
	 [ auto | default | none |<br>
	 context-menu | help | pointer | progress | wait | <br>
	 cell | crosshair | text | vertical-text | <br>
	 alias | copy | move | no-drop | not-allowed | grab | grabbing | <br>
	 e-resize | n-resize | ne-resize | nw-resize | s-resize | se-resize | sw-resize | w-resize |
	 ew-resize | ns-resize | nesw-resize | nwse-resize |
	 col-resize | row-resize |
	 all-scroll |<br>
	 zoom-in | zoom-out <br>
	 ]
	Initial: auto
	Applies to: all elements
	Inherited: yes
	Percentages: N/A
	Computed value: as specified, except with any relative URLs converted to absolute
	Animation type: discrete
	</pre>

	This property specifies the type of cursor to be displayed for the pointing device
	when the cursor's hotspot is within the element's <a>border edge</a>.

	Note: As per [[css-backgrounds-3#border-radius]], the <a>border edge</a> is affected by 'border-radius'.

	In the case of overlapping elements,
	which element determines the type of cursor
	is based on hit testing:
	the element determining the cursor
	is the one that would receive a click
	initiated from this position.

	Note: The specifics of hit testing
	are out of scope of this specification.
	Hit testing will hopefully be defined
	in a future revision of CSS or HTML.

	User agents may ignore the cursor property
	over native user agent controls such as scrollbars, resizers, or other native UI widgets
	e.g. those that may be used inside some user agent specific implementations of form elements.
	User agents may also ignore the 'cursor' property
	and display a cursor of their choice
	to indicate various states of the UA's user interface,
	such as a busy cursor when the page is not responding,
	or a text cursor when the user is performing text selection.

	Note: [[HTML]] defines <a href="https://html.spec.whatwg.org/multipage/rendering.html#image-maps-2">special handling of image maps</a>
	for the 'cursor' property.

	Values have the following meanings:

	<style>
	#cursors dfn { cursor: inherit }
	</style>
	<dl dfn-type=value dfn-for=cursor id=cursors>
		<dt>image cursors
		<dd>
			The first (optional) component of the 'cursor' property
			is a list of image-based cursors.
			If the user agent cannot handle the first cursor of a list of cursors,
			it must attempt to handle the second, etc.
			If the user agent cannot handle any of these author-defined cursors,
			it must use the keyword-based cursor at the end of the list.

			Each author-defined image-based cursor is defined by the following values:

			<dl>
				<dt><<url>> | <<url-set>>
				<dd>
					The user agent retrieves the cursor from the resource designated by the <<url>> or <<url-set>>.
					Conforming user agents may, instead of <<url>> and <<url-set>>,
					support <<image>> which is a superset.

					<dfn type>&lt;url-set></dfn> is a limited version of ''image-set()'',
					where the <<image>> sub-production is restricted to <<url>> only.

					The UA must support the following image file formats:

					<ul>
						<li>
							PNG, as defined in [[!PNG]]

						<li>
							SVG, as defined in [[!SVG11]],
							in <a href="https://www.w3.org/TR/SVG2/conform.html#secure-static-mode">secure static mode</a> [[!SVG2]],
							if it has a [=natural size=].

						<li>
							any other non-animated image file format that they support
							for <<image>> in other properties,
							such as the 'background-image' property
					</ul>

					In addition, the UA should support the following image file formats:

					<ul>
						<li>
							SVG, as defined in [[!SVG11]],
							in <a href="https://www.w3.org/TR/SVG2/conform.html#secure-animated-mode">secure animated mode</a> [[!SVG2]],
							if it has a [=natural size=].

						<li>
							any other animated image file format that they support
							for <<image>> in other properties,
							such as the 'background-image' property
					</ul>

					The UA may also support additional file formats,
					including SVG, as defined in [[!SVG11]],
					in secure static mode or secure animated mode [[!SVG2]],
					even if it does not have a [=natural size=].

					Note: The CSS Working Group initially intended support for all SVG,
					naturally sized or not.
					Support for non-naturally sized SVG was downgraded from mandatory to optional due
					to lack of implementations.

					Note: For a number of years,
					the only file formats supported for cursors in common desktop browsers were
					the .ico and .cur file formats, as designed by Microsoft.
					Although this is no longer the case
					(PNG and SVG have broad support),
					for compatibility with legacy content,
					UAs are encouraged to support these,
					even though the lack of an open specification
					makes it impossible to have a normative requirement
					about these formats.
					Some information on these formats can be found
					<a href="https://en.wikipedia.org/wiki/ICO_%28file_format%29">on Wikipedia</a>.

					The <a>default object size</a> for cursor images is
					a UA-defined size that should be based on
					the size of a typical cursor on the UA's operating system.

					The <a>concrete object size</a> is determined using
					the <a>default sizing algorithm</a>.
					If an operating system is
					<strong>incapable</strong> of rendering a cursor above a given size,
					cursors larger than that size must be shrunk to within
					the OS-supported size bounds,
					while maintaining the cursor image's [=natural aspect ratio=], if any.

					The optional &lt;x&gt; and &lt;y&gt; coordinates
					identify the exact position within the image which is the pointer position (i.e., the hotspot).

				<dt>&lt;x&gt;
				<dt>&lt;y&gt;
				<dd>
					Each is a <<number>>.
					The x-coordinate and y-coordinate of the position
					in the cursor's coordinate system (left/top relative)
					which represents the precise position that is being pointed to.

					Note: This specification does not define
					how the coordinate systems of the various types of <<image>> are established,
					and defers these definitions to [[CSS-IMAGES-4]].

					If the values are unspecified,
					then the natural hotspot defined inside the image resource itself is used.
					If both the values are unspecific and the referenced cursor has no defined hotspot,
					the effect is as if a value of "0 0" was specified.

					If the coordinates of the hotspot,
					as specified either inside the image resource or
					by &lt;x&gt; and &lt;y&gt; values,
					fall outside of the cursor image,
					they must be clamped (independently) to fit.
			</dl>

		<dt>general purpose cursors
		<dd>
		<dl>
			<dt style="cursor:auto"><dfn>auto</dfn>
			<dd>
				The UA determines the cursor to display based on the current context.
				Specifically, ''cursor/auto'' behaves as ''cursor/text'' over selectable text or editable elements,
				and ''cursor/default'' otherwise.

				Note: When over selectable text or editable elements,
				as it does with ''cursor/text'',
				the UA must use a vertical or horizontal text cursor,
				as appropriate for the [=writing mode=] of the element,
				and may take transforms and other visual effects into account as well.

			<dt style="cursor:default"><dfn>default</dfn>
			<dd>
				The platform-dependent default cursor.
				Often rendered as an arrow.

			<dt style="cursor:none"><dfn>none</dfn>
			<dd>
				No cursor is rendered for the element.
		</dl>

		<dt>links and status cursors
		<dd>
		<dl>
			<dt style="cursor:context-menu"><dfn>context-menu</dfn>
			<dd>
				A context menu is available for the object under the cursor.
				Often rendered as an arrow with a small menu-like graphic next to it.

			<dt style="cursor:help"><dfn>help</dfn>
			<dd>
				Help is available for the object under the cursor.
				Often rendered as a question mark or a balloon.

			<dt style="cursor:pointer"><dfn>pointer</dfn>
			<dd>
				The cursor is a pointer that indicates a link.
				Often rendered as the backside of a hand with the index finger extended.

				Unless otherwise specified,
				UAs must apply ''cursor: pointer'' to hyperlinks
				for all supported document formats
				via the <a lt="User-Agent Origin">UA stylesheet</a>,
				using a normal (i.e. not ''!important'') declaration.

				Authors should use pointer on links and may use on other interactive elements.

			<dt style="cursor:progress"><dfn>progress</dfn>
			<dd>
				A progress indicator.  The program is performing some processing,
				but is different from ''wait'' in that the user may still interact
				with the program. Often rendered as a spinning beach ball,
				or an arrow with a watch or hourglass.

			<dt style="cursor:wait"><dfn>wait</dfn>
			<dd>
				Indicates that the program is busy and the user should wait.
				Often rendered as a watch or hourglass.
		</dl>

		<dt>selection cursors
		<dd>
		<dl>
			<dt style="cursor:cell"><dfn>cell</dfn>
			<dd>
				Indicates that a cell or set of cells may be selected.
				Often rendered as a thick plus-sign with a dot in the middle.

			<dt style="cursor:crosshair"><dfn>crosshair</dfn>
			<dd>
				A simple crosshair (e.g., short line segments resembling a "+" sign).
				Often used to indicate a two dimensional bitmap selection mode.

			<dt style="cursor:text"><dfn>text</dfn>
			<dd>
				Indicates text that may be selected. Often rendered as an I-beam.
				User agents must automatically display
				a vertical I-beam/cursor over elements with a horizontal [=writing mode=],
				and a horizontal I-beam/cursor
				(e.g. same as the ''vertical-text'' keyword)
				over elements in a vertical [=writing mode=].
				Additionally, user agents may take transforms (see [[CSS-TRANSFORMS-1]])
				or other visual effects such as text on a path (See [[SVG2/text#TextLayoutPath]]),
				when choosing between the horizontal or vertical text cursor,
				and may display any angle of I-beam/cursor for text that is rendered at any particular angle.

			<dt style="cursor:vertical-text"><dfn>vertical-text</dfn>
			<dd>
				Indicates vertical-text that may be selected.
				Often rendered as a horizontal I-beam.
		</dl>

		<dt>drag and drop cursors
		<dd>
		<dl>
			<dt style="cursor:alias"><dfn>alias</dfn>
			<dd>
				Indicates an alias of/shortcut to something is to be created.
				Often rendered as an arrow with a small curved arrow next to it.

			<dt style="cursor:copy"><dfn>copy</dfn>
			<dd>
				Indicates something is to be copied.
				Often rendered as an arrow with a small plus sign next to it.

			<dt style="cursor:move"><dfn>move</dfn>
			<dd>
				Indicates something is to be moved.

			<dt style="cursor:no-drop"><dfn>no-drop</dfn>
			<dd>
				Indicates that the dragged item cannot be dropped at the current cursor location.
				Often rendered as a hand or pointer with a small circle with a line through it.

			<dt style="cursor:not-allowed"><dfn>not-allowed</dfn>
			<dd>
				Indicates that the requested action will not be carried out.
				Often rendered as a circle with a line through it.

			<dt caniuse="css3-cursors-grab" id=cursor-grab style="cursor:grab"><dfn>grab</dfn>
			<dd>
				Indicates that something can be grabbed (dragged to be moved).
				Often rendered as the backside of an open hand.

			<dt style="cursor:grabbing"><dfn>grabbing</dfn>
			<dd>
				Indicates that something is being grabbed (dragged to be moved).
				Often rendered as the backside of a hand with fingers closed mostly out of view.
		</dl>

		<dt>resizing and scrolling cursors
		<dd>
		<dl>
			<dt>
				<span style="cursor:e-resize"><dfn>e-resize</dfn></span>,
				<span style="cursor:n-resize"><dfn>n-resize</dfn></span>,
				<span style="cursor:ne-resize"><dfn>ne-resize</dfn></span>,
				<span style="cursor:nw-resize"><dfn>nw-resize</dfn></span>,
				<span style="cursor:s-resize"><dfn>s-resize</dfn></span>,
				<span style="cursor:se-resize"><dfn>se-resize</dfn></span>,
				<span style="cursor:sw-resize"><dfn>sw-resize</dfn></span>,
				<span style="cursor:w-resize"><dfn>w-resize</dfn></span>
			<dd>
				Indicates that some edge is to be moved.
				For example, the ''se-resize'' cursor is used
				when the movement starts from the south-east corner of the box.