css-ui-4/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/
Indent: 2
</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:selectors-4; type:dfn; text:host language
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
spec:css-borders-4; type:property;
	text:box-shadow
	text:border-top-style
	text:border-left-style
	text:border-right-style
	text:border-bottom-style
	text:border-top-width
	text:border-left-width
	text:border-right-width
	text:border-bottom-width
	text:border-top-color
	text:border-left-color
	text:border-right-color
	text:border-bottom-color
	text:border-start-start-radius
	text:border-start-end-radius
	text:border-end-start-radius
	text:border-end-end-radius
	text:border-top-left-radius
	text:border-top-right-radius
	text:border-bottom-left-radius
	text:border-bottom-right-radius
	text:border-block-start-width
	text:border-block-end-width
	text:border-inline-start-width
	text:border-inline-end-width
	text:border-block-start-style
	text:border-block-end-style
	text:border-inline-start-style
	text:border-inline-end-style
	text:border-block-start-color
	text:border-block-end-color
	text:border-inline-start-color
	text:border-inline-end-color
spec:dom; type:dfn; text:element
spec:infra; type:dfn; text:user agent
</pre>
<pre class=anchors>
urlPrefix: https://html.spec.whatwg.org/multipage/; spec:HTML
	type:attr-value; text:password; for:input/type; url: input.html#attr-input-type-password-keyword
	type:element-attr; text:inert; for:html-global; url: interaction.html#the-inert-attribute
</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,
	as well as the 'corner-shape'.

	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 elements in the 
		'':focus-visible'' state, and a thick red line when it is in the 
		'':active'' state, the following rules can be used:
		<pre><code class="lang-css">
		:focus-visible  { 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: <<cursor-image>>#? <<cursor-predefined>>
	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:

	<dl dfn-type=value dfn-for=cursor id=cursors>
		<dt><dfn><<cursor-image>></dfn>
		<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.

			A <<cursor-image>> has the following syntax:

			<pre class=prod>
				<dfn type>&lt;cursor-image></dfn> = [ <<url>> | <<url-set>> ] <<number>>{2}?
			</pre>

			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 a 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 pair of <<number>> values
			give the X and Y coordinates
			of the exact position within the image which is the pointer position (i.e., the hotspot),
			as offsets from the left/top of the image.

			Note: This specification does not define
			how the coordinate systems of the various types of <<image>> are established,
			and defers these definitions to [[CSS4-IMAGES]].

			If the values are omitted,
			then the natural hotspot defined inside the image resource itself is used.
			If it has no natural hotspot,
			the top left corner of the image is used,
			as if ''0 0'' were provided.

			If the X or Y coordinates of the hotspot
			(whether specified explicitly or taken from the image)
			fall outside of the cursor image,
			they must be clamped (independently) to fit.

		<dt><dfn><<cursor-predefined>></dfn>
		<dd>The mandatory <<cursor-predefined>> keyword
			specifies a predefined cursor to use,
			or the <em>fallback</em> cursor to be used
			if <<url>>s were provided
			and none of them can be successfully used.

			See [[#predefined-cursors]] for the full set of <<cursor-predefined>> keywords
			and their meanings.
	</dl>

	<div class="example">
		Here is an example of using several cursor values.
		<pre><code class="lang-css">
		:link,:visited {
			cursor: url(example.svg),
				url(hyper.cur),
				url(hyper.png) 2 3,
				pointer
		}
		</code></pre>

		This example sets the cursor on all hyperlinks (whether visited or not)
		to an external SVG image to be used as a cursor.
		If that fails to load, user agents  would simply skip
		to the next value and attempt to use the "hyper.cur" cursor.
		If that cursor format was also not supported,
		the UA could attempt to use the "hyper.png" cursor with the explicit hotspot.
		Finally, if the UA cannot load any of those image cursors, the UA would skip to the last value
		and render the ''pointer'' cursor.
	</div>


<h5 id="predefined-cursors">
Predefined Cursors</h5>

	The <<cursor-predefined>> production encompasses a broad selection of predefined cursors,
	present on most operating systems.
	Its syntax is:

	<pre class=prod>
	<dfn><<cursor-predefined>></dfn> = auto | default | none |
	                context-menu | help | pointer | progress | wait |
	                cell | crosshair | text | vertical-text |
	                alias | copy | move | no-drop | not-allowed | grab | grabbing |
	                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 |
	                zoom-in | zoom-out
	</pre>

	The <<cursor-predefined>> keywords have the following meanings
	and likely renderings:

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

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

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

	<dt>links and status cursors
	<dd>
		<dl>
			<dt><dfn style="cursor:context-menu">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><dfn style="cursor:help">help</dfn>
			<dd>Help is available for the object under the cursor.
				Often rendered as a question mark or a balloon.

			<dt><dfn style="cursor:pointer">pointer</dfn>
			<dd>The cursor is a pointer that indicates a link.

			<dt><dfn style="cursor:progress">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><dfn style="cursor:wait">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><dfn style="cursor:cell">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><dfn style="cursor:crosshair">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><dfn style="cursor:text">text</dfn>
			<dd>Indicates text that may be selected. Often rendered as a vertical I-beam.
				User agents may automatically display a horizontal I-beam/cursor
				(e.g. same as the ''vertical-text'' keyword)
				for vertical text, or for that matter,
				any angle of I-beam/cursor for text that is rendered at any particular angle.

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

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

			<dt><dfn style="cursor:no-drop">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><dfn style="cursor:not-allowed">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><dfn caniuse=css3-cursors-grab style="cursor:grab">grab</dfn>
			<dd>Indicates that something can be grabbed (dragged to be moved).
				Often rendered as the backside of an open hand.
			<dt><dfn style="cursor:grabbing">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><dfn style="cursor:e-resize">e-resize</dfn>
			<dt><dfn style="cursor:n-resize">n-resize</dfn>
			<dt><dfn style="cursor:ne-resize">ne-resize</dfn>
			<dt><dfn style="cursor:nw-resize">nw-resize</dfn>
			<dt><dfn style="cursor:s-resize">s-resize</dfn>
			<dt><dfn style="cursor:se-resize">se-resize</dfn>
			<dt><dfn style="cursor:sw-resize">sw-resize</dfn>
			<dt><dfn style="cursor:w-resize">w-resize</dfn>
			<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.

			<dt><dfn style="cursor:ew-resize">ew-resize</dfn>
			<dt><dfn style="cursor:ns-resize">ns-resize</dfn>
			<dt><dfn style="cursor:nesw-resize">nesw-resize</dfn>
			<dt><dfn style="cursor:nwse-resize">nwse-resize</dfn>
			<dd>Indicates a bidirectional resize cursor.

			<dt><dfn style="cursor:col-resize">col-resize</dfn>
			<dd>Indicates that the item/column can be resized horizontally.
				Often rendered as arrows pointing left and right with a vertical bar separating them.

			<dt><dfn style="cursor:row-resize">row-resize</dfn>
			<dd>Indicates that the item/row can be resized vertically.
				Often rendered as arrows pointing up and down with a horizontal bar separating them.

			<dt><dfn style="cursor:all-scroll">all-scroll</dfn>
			<dd>Indicates that the something can be scrolled in any direction.
				Often rendered as arrows pointing up, down, left, and right with a dot in the middle.
		</dl>

	<dt caniuse="css3-cursors-newer" id="zooming-cursors">zooming cursors
	<dd>
		<dl>
			<dt><dfn style="cursor:zoom-in">zoom-in</dfn>
			<dt><dfn style="cursor:zoom-out">zoom-out</dfn>
			<dd>
				Indicates that something can be zoomed (magnified) in or out, and
				often rendered as a magnifying glass with a "+" or "-" in the center of the glass, for ''zoom-in'' and ''zoom-out'' respectively.
		</dl>
	</dl>


<h5 id="canvas_cursor">
Cursor of the canvas</h5>

	The document <a href="https://www.w3.org/TR/CSS21/intro.html#the-canvas">canvas</a>
	is the infinite surface over which the document is rendered [[!CSS21]].
	Since no element corresponds to the canvas,
	in order to allow styling of the cursor when not over any element,
	the canvas cursor re-uses the root element's cursor.
	However, if no boxes are generated for the root element
	(for example, if the root element has ''display: none''),
	then the canvas cursor is the platform-dependent default cursor.

	Note: An element might be invisible
	but still generate boxes. For example,
	if the element has ''visibility: hidden'' but not ''display: none'',
	boxes are generated for it and its cursor is used for the canvas.


<h3 id="the-insertion-caret">
Insertion caret</h3>

	The <dfn lt="insertion caret|caret">insertion caret</dfn> (or “caret” for short)
	is a visible indicator of the insertion point in an element that [=accepts text input=],
	where text (and potentially other content) can be inserted by the user.
	The 'caret-color', 'caret-animation', and 'caret-shape' properties
	give the author some amount of control over the appearance of the [=caret=].

	Text or elements are considered to <dfn>accept text input</dfn>
	if they are either an [=editable element=] or a descendent thereof,
	excluding any such element where the [=used value=] of 'user-select' is ''user-select/none'',
	as well as subtrees rooted at an HTML element with a {{ElementContentEditable/contentEditable}} attribute set to <code>false</code>.

	Some user agents have other user interface mechanisms
	with a similar appearance,
	also occasionally referred to as “carets”.
	For example, some UAs can show a “navigation caret”,
	which acts similarly to an [=insertion caret=]
	but can be moved around in non-editable text.
	The 'caret-color', 'caret-animation', and 'caret-shape' properties
	are not intended to apply to such mechanisms
	nor outside of [=editable elements=],
	though user agents may choose to take them into account.
	Whether to do so and to what extent is up to the user agent.

	Note: The cursor image shown
	when hovering over text when the 'cursor' property is ''cursor/auto'',
	or when hovering over an element where the 'cursor' property is ''cursor/text'' or ''cursor/vertical-text'',
	though it sometimes resembles a caret,
	is not a caret (it's a cursor).

<h4 id="caret-color" caniuse="css-caret-color">
Coloring the Insertion Caret: the 'caret-color' property</h4>

	<pre class="propdef">
	Name: caret-color
	Value: auto | <<color>>
	Initial: auto
	Applies to: text or elements that [=accept text input=]
	Inherited: yes
	Percentages: N/A
	Computed value: The computed value for ''caret-color/auto'' is ''caret-color/auto''.
	 For <<color>> values, see [[CSS-COLOR-4#resolving-color-values]].
	Animation Type: by computed value
	</pre>

	This property controls the color of the [=insertion caret=].

	<dl>
		<dt>auto
		<dd>
			User agents should use ''currentColor''.
			User agents may automatically adjust the color of [=caret=]
			to ensure good visibility and contrast with the surrounding content,
			possibly based on the currentColor, background, shadows, etc.

			Note: When 'caret-shape' is ''caret-shape/block'',
			ensuring good visibility and contrast
			is best achieved with a UA-determined color other than ''currentColor''.

		<dt><<color>>
		<dd>
			The [=caret=] is colored with the specified color.
	</dl>

	<div class="example">
		Example: a textarea with
		<code class="lang-css">caret-color:#00aacc;</code>

		<textarea style="caret-color:#00aacc;">
		caret-color:#00aacc
		</textarea>
	</div>


<h4 id="caret-animation">
Animation of the insertion caret: 'caret-animation'</h4>

	<pre class='propdef'>
	Name: caret-animation
	Value: auto | manual
	Initial: auto
	Applies to: text or elements that [=accept text input=]
	Inherited: yes
	Percentages: N/A
	Computed value: specified keyword
	Animation type: discrete
	</pre>

	On most platforms and in most UAs,
	the [=insertion caret=] blinks.
	This property allows the author
	to take control over the way the [=caret=] is animated.

	<dl dfn-type=value dfn-for=caret-animation>
		<dt><dfn>auto</dfn>
		<dd>
			The UA determines how the [=caret=] should be animated, if at all,
			as well as the speed of any such animation.
			It should match platform conventions and settings,
			and may be adjusted based on context.

			Note: This is typically rendered as a blinking [=caret=].
			Fading in and out instead of blinking is a variant that appears in some environments.

		<dt><dfn>manual</dfn>
		<dd>
			The UA must not animate the [=caret=].

			Note: This is only about UA-driven animations of the [=caret=].
			When CSS animations are used to animate the [=caret=] color,
			they apply normally.
	</dl>

	Note: It is recommended for authors to stop the [=caret=] from blinking or fading
	using ''caret-animation: manual''
	when applying custom animations using [[CSS3-ANIMATIONS]],
	to prevent the UA's animation and the CSS animation to interfere.

	Note: See <a href="https://www.w3.org/TR/WCAG20/#seizure">Guideline 2.3: Seizures: Do not design content in a way that is known to cause seizures</a> [[WCAG20]].

	<div class=example>
		A user who is disturbed by or has adverse reactions to blinking or flashing visuals
		may want to make all [=carets=] static and non-blinking,
		regardless of platform defaults or author settings.
		This can be accomplished with the following rule in the user stylesheet.

		<pre><code class="lang-css">
		/* prevent the caret from blinking/flashing */
		:read-write { caret-animation: manual !important; }

		/* prevent changes of caret-color, including animations */
		:read-write { caret-color: auto !important; }
		</code></pre>
	</div>

	UAs that do not have an editable user stylesheet
	should provide a setting to disable
	<a href="https://www.w3.org/TR/WCAG20/#blinksdef">blinking</a>,
	<a href="https://www.w3.org/TR/WCAG20/#flash-def">flashing</a>,
	and animated [=carets=].
	UAs that do have an editable user stylesheet may want to provide this setting as well.
	See [[WCAG]] <a href="https://www.w3.org/TR/WCAG20/#time-limits-pause">Guideline 2.2</a>
	and <a href="https://www.w3.org/TR/WCAG20/#seizure">Guideline 2.3</a>
	for details.

	<div class=example>
		Typically, the [=caret=] blinks on and off.
		This makes it alternate between 2 colors.
		<pre><code class="lang-css">
		textarea {
			caret-animation: manual;
			caret-color: blue;
			animation: caret-alternate 2s step-end infinite;
		}
		@keyframes caret-alternate {
			50% { caret-color: red; }
		}
		</code></pre>

		The simulated rendering below illustrates how this is expected to look.
		<style>
		@keyframes caret-alternate-ref { 50% { border-color: red; } }
		</style>
		<div style="border:inset; background: white; width: 10em;">
			Text area
			with color-alternating caret<span style="border-right: 2px solid blue; animation: caret-alternate-ref 2s step-end infinite;"></span>
		</div>

		Focus the element below to see how your browser renders it.
		<style>
		@keyframes caret-alternate-test {
			50% { caret-color: red; }
		}
		</style>
		<div contentEditable=true
		     style="border:inset; background: white; width: 10em;
		            caret-animation: manual;
		            caret-color: blue;
		            animation: caret-alternate-test 2s step-end infinite;"
		>Text area with color-alternating caret</div>
	</div>

	<div class=advisement>
		If a user agent is unwilling to yield control of [=caret=] animations
		to page authors and would not honor ''caret-animation: manual'',
		it must not implement the property at all.

		Note:
		This enables authors to use <code highlight="css">@supports (caret-animation: manual) { … }</code>
		to gate code that would depend on this functionality.
		See [[CSS-CONDITIONAL-3]].
	</div>


<h4 id="caret-shape">
Shape of the insertion caret: 'caret-shape'</h4>

	<pre class='propdef'>
	Name: caret-shape
	Value: auto | bar | block | underscore
	Initial: auto
	Applies to: text or elements that [=accept text input=]
	Inherited: yes
	Percentages: N/A
	Computed value: specified keyword
	Animation type: by computed value
	</pre>

	This property allows authors to specify
	the desired shape of the [=insertion caret=].

	Within the context of this definition, <dfn>character</dfn> is
	to be understood as <em>extended grapheme cluster</em>,
	as defined in [[!UAX29]], and <dfn>visible character</dfn>
	means a character with a non-zero advance measure.

	<dl dfn-type=value dfn-for=caret-shape>
		<dt><dfn>auto</dfn>
		<dd>
			The UA determines the shape of the [=caret=].
			It should match platform conventions,
			and may be adjusted based on context.
			For example, if a UA switches between insert mode and overtype mode when the
			user presses the <em>insert</em> key on their keyboard,
			it may show a ''caret-shape/bar'' [=caret=] in insert mode,
			and a ''caret-shape/block'' [=caret=] in overtype mode.

		<dt><dfn>bar</dfn>
		<dd>
			The UA must render the [=insertion caret=]
			as a thin bar placed at the insertion point.
			This means it is between, before, or after <a>characters</a>, not over them.
			It should be perpendicular to the inline progression direction,
			although UAs may render it slanted when inserting italic or oblique text.

		<dt><dfn>block</dfn>
		<dd>
			The UA must render the [=insertion caret=]
			as a rectangle overlapping the next <a>visible character</a> following the insertion point.
			If there is no <a>visible character</a> after the insertion point,
			the UA must render the caret after the last <a>visible character</a>.
			UAs may render it as a slanted rectangle when inserting italic or oblique text.

		<dt><dfn>underscore</dfn>
		<dd>
			The UA must render the [=insertion caret=]
			as a thin line <a>under</a> (as defined in [[!CSS-WRITING-MODES-3]])
			the next <a>visible character</a> following the insertion point.
			If there is no <a>visible character</a> after the insertion point,
			the UA must render the caret after the last <a>visible character</a>.
	</dl>

	The width of the ''caret-shape/block'' and ''caret-shape/underscore'' [=carets=]
	should be the advance measure of the next <a>visible character</a> after the insertion point,
	or ''1ch'' if there is no next <a>visible character</a>
	or if this information is impractical to determine.

	When determining the orientation and appearance of the [=caret=],
	UAs must take into account the <a>writing mode</a> [[!CSS-WRITING-MODES-3]]
	and must apply transformations [[!CSS-TRANSFORMS-1]].
	If the edited text is laid out on a path,
	for instance by using the SVG <{textPath}> element,
	UAs should also account for this.

	The thickness of ''caret-shape/bar'' and ''caret-shape/underscore'' [=carets=]--
	as well as that of ''caret-shape/auto'' [=carets=] with a similar rendering--
	is determined by the user agent.
	When practical, the user agent should choose a thickness that ensures
	the [=caret=] remains visible even if it has been scaled down
	via means such as transformations [[CSS-TRANSFORMS-1]].

	When there is not enough room at the end of a line
	to display the caret positioned there,
	the user agents should still display it,
	even if that means means painting
	past the bounds of the [=scrollable overflow area=];
	user agents may impose limits on this and clip as necessary.
	User agents may also visually reposition a caret
	in order to display it within the [=scrollport=]
	if it would otherwise be invisible.

	The stacking position of the [=caret=] is left undefined within the following constraints:

	<ul>
		<li>
			The [=caret=] must not be obscured by the background of the element.

		<li>
			UAs must render ''caret-shape/block'' [=carets=]
			so that the character it overlaps with is not obscured by the [=caret=].
	</ul>

	<div class=example>
		This illustrates the typical appearance of the various [=caret=] shapes.
		In each of the sample renderings below,
		the insertion point is between the letters u and m.

		<style>
		@keyframes caret-bar-ref { 50% { border-color: transparent; } }
		@keyframes caret-block-ref { 50% { background: transparent; } }
		@keyframes caret-underscore-ref { 50% { border-color: transparent; } }
		#caret-shape-example {
			min-width: 25em;
		}
		#caret-shape-example,
		#caret-shape-example td,
		#caret-shape-example th {
			border: solid 1px;
		}
		#caret-shape-example td+td {
			background:white;
		}
		</style>
		<table id="caret-shape-example">
			<tr>
				<th>'caret-shape'
				<th>Sample rendering
				<th>Your browser<br>(focus each cell to see the [=caret=])

			<tr>
				<td>''bar''
				<td>Lorem ipsu<span style="border: 1px solid black; margin: 0 -1px; animation: caret-bar-ref 2s step-end infinite;">&#8203;</span>m
				<td contentEditable=true style="caret-shape: bar">Lorem Ipsum

			<tr>
				<td>''caret-shape/block''
				<td>Lorem ipsu<span style="background: #bbb; animation: caret-block-ref 2s step-end infinite;">m</span>
				<td contentEditable=true style="caret-shape: block">Lorem Ipsum

			<tr>
				<td>''underscore''
				<td>Lorem ispu<span style="border-bottom: 2px solid black; animation: caret-underscore-ref 2s step-end infinite;">m</span>
				<td contentEditable=true style="caret-shape: underscore">Lorem Ipsum
		</table>
	</div>

	<div class=example>
		''caret-shape/underscore'' or ''caret-shape/block'' [=carets=] are commonly used
		in terminals and command lines,
		as in this example.
		<pre><code class="lang-css">
		.console {
			caret-shape: underscore;
			background: black;
			color: white;
			font-family: monospace;
			padding: 1ex;
		}
		</code></pre>

		The simulated rendering below illustrates how this is expected to look.
		<style>
		@keyframes terminal-caret-ref { 50% { border-color: transparent; } }
		</style>
		<pre style="background: black; color: white; font-family: monospace; padding: 1ex">
		user@host:css-ui-4 $ ls -a
		. .. Overview.bs Overview.html
		user@host:css-ui-4 $ <span style="border-bottom: 2px solid white;animation: terminal-caret-ref 2s step-end infinite;">&nbsp;</span>
		</pre>

		Focus the element below to see how your browser renders it.
		<pre contentEditable=true style="background: black; color: white; font-family: monospace; padding: 1ex; caret-shape: underscore;">
		user@host:css-ui-4 $ ls -a
		. .. Overview.bs Overview.html
		user@host:css-ui-4 $&nbsp;
		</pre>
	</div>


	<h4 id="caret">
	Insertion caret shorthand: 'caret'</h4>

	<pre class='propdef shorthand'>
	Name: caret
	Value: <<'caret-color'>> || <<'caret-animation'>> || <<'caret-shape'>>
	Initial: auto
	Applies to: text or elements that [=accept text input=]
	Inherited: yes
	Percentages: N/A
	</pre>

	This property is a shorthand for setting
	'caret-color', 'caret-animation', and 'caret-shape' in one declaration.
	Omitted values are set to their initial values.

	<div class=example>
		This example illustrates using the various [=caret=]-related properties
		in combination.
		They are used here to simulate the appearance of the [=caret=]
		on an old phosphor computer monitor.

		<pre><code class="lang-css">
		#old-screen {
			caret: block manual;
			animation: old-caret 2s infinite;
			/*styling of the screen omitted for brevity */
		}
		@keyframes old-caret {
			from, 50% { caret-color: green; }
			75%, to { caret-color: transparent; }
		}
		</code></pre>

		The simulated rendering below illustrates how this is expected to look.
		<style>
		.old-screen {
			border-radius: 1em;
			padding: 1em;
			color: green;
			font-family: monospace;
			white-space: pre;
			background: repeating-linear-gradient(#030 0px, #030 1px, #020 1px, #020 3px);
		}

		.old-screen[contentEditable] {
			caret: block manual;
			animation: caret-old 2s  infinite;
		}
		.old-screen span {
			display:inline-block;
			white-space: pre;
			animation: caret-old-ref 2s  infinite;

		}
		@keyframes caret-old-ref {
			from, 50% { background-color: green; }
			75%, to { background-color: transparent; }
		}
		@keyframes caret-old {
			from, 50% { caret-color: green; }
			75%, to { caret-color: transparent; }
		}
		</style>
		<div class="old-screen" style="height: 100px">&gt; <span>&nbsp;</span></div>

		Focus the element below to see how your browser renders it.
		<div class="old-screen" contentEditable="true" style="height: 100px">&gt; </div>
	</div>


<h3 id="keyboard">
Keyboard control</h3>

<h4 id="nav-dir">
Directional Focus Navigation: the 'nav-up', 'nav-right', 'nav-down', 'nav-left' properties</h4>

	<pre class="propdef">
	Name: nav-up , nav-right , nav-down , nav-left
	Value: auto | <<id>> [ current | root | <<target-name>> ]?
	Initial: auto
	Applies to: all enabled elements
	Inherited: no
	Percentages: N/A
	Computed value: as specified
	Animation type: discrete
	</pre>

	<dl>
		<dt>auto
		<dd>The user agent automatically determines which element to navigate the focus to in response to directional navigational input.

		<dt><dfn noexport><<id>></dfn>
		<dd>
			The <<id>> value is an ID selector [[SELECT]].
			In response to directional navigation input corresponding to the property,
			the focus is navigated to the first element in tree order matching the selector.

			If this refers to the currently focused element,
			the directional navigation input respective to the nav- property is ignored &mdash;
			there is no need to refocus the same element.

			If no element matches the selector,
			the user agent automatically determines which element to navigate the focus to.

			If the focus is navigated to an element
			that was not otherwise focusable,
			it becomes focusable
			only as the result of this directional navigation,
			and the '':focus'' pseudo-class matches the element
			while it is focused as such.

			Note: there were other options under consideration for such "not otherwise focusable" elements,
			including focus to the next otherwise focusable element in the document tree
			(including descendants of such a not otherwise focusable element).
			Input on such other options is welcome and explicitly solicited,
			especially from implementation experiences and author experience using the directional navigation properties in their content.

		<dt><dfn noexport><<target-name>></dfn>
		<dd>
			The &lt;target-name&gt; parameter indicates the target frame for the focus navigation.
			It is a <<string>> and it MUST NOT start with the underscore "_" character.
			Error handling: if it does start with an underscore, "_parent" navigates to the parent frame,
			"_root" is treated as ''nav-up/root'',
			and other values navigate to a frame by that name if it exists.
			If the specified target frame does not exist,
			the parameter will be treated as the keyword ''nav-up/current'',
			which means to simply use the frame that the element is in.
			The keyword ''nav-up/root'' indicates that the user agent should target the full window.
	</dl>

	User agents for devices with directional navigation keys
	respond by navigating the focus according to four respective nav-* directional navigation properties
	(nav-up, nav-right, nav-down, nav-left).
	This specification does not define which keys of a device are directional navigational keys.

	Note: Typical personal computers have keyboards with four arrow keys.
	One possible implementation would be to use those four arrow keys for directional navigation.
	For accessibility and user convenience,
	user agents should allow configuration of which keys on a keyboard are used for directional navigation.

	<div class="example">
		<h5 id=example-positioned-buttons>Example: positioned buttons</h5>

		Here is an example of buttons positioned in a diamond shape
		whose directional focus navigation is set in such a way
		to navigate the focus clockwise (or counter-clockwise) around the diamond shape
		when the user chooses to navigate directionally.
		<pre><code class="lang-css">
		button { position:absolute }

		button#b1 {
			top:0; left:50%;
			nav-right:#b2; nav-left:#b4;
			nav-down:#b2; nav-up:#b4;
		}

		button#b2 {
			top:50%; left:100%;
			nav-right:#b3; nav-left:#b1;
			nav-down:#b3; nav-up:#b1;
		}

		button#b3 {
			top:100%; left:50%;
			nav-right:#b4; nav-left:#b2;
			nav-down:#b4; nav-up:#b2;
		}

		button#b4 {
			top:50%; left:0;
			nav-right:#b1; nav-left:#b3;
			nav-down:#b1; nav-up:#b3;
		}
		</code></pre>

		Whatever markup sequence the buttons may have
		(which is not specified in this example)
		is irrelevant in this case because they are positioned, and yet,
		it is still important to ensure focus navigation behaviors which relate reasonably to the specified layout.
	</div>

	<div class="example">
		<h5 id=example-moving-focus-to-inside-a-frame>Example: moving focus to inside a frame</h5>

		Moving the focus to an element in a specific frame requires both the element's id and the frame's name.

		This example shows how to make navigating left from the button with id "foo" move the focus to the element with id "bar" within the frame named "sidebar".

		<pre><code class="lang-css">
		button#foo { nav-left: #bar "sidebar"; }
		</code></pre>
	</div>


<h4 id="input-method-editor">
Obsolete: the ime-mode property</h4>

	''ime-mode'' is a property somewhat implemented in some browsers
	that is problematic and officially obsoleted by this specification
	and its predecessor [[CSS-UI-3]].

	There is documentation of
	<a href="https://developer.mozilla.org/en-US/docs/Web/CSS/ime-mode">non-interoperability of these implementations.</a>

	User agents should not support the <css>ime-mode</css> property.

	Authors must not use the ime-mode property.

	Users may use the ime-mode property only for repair use cases
	where they have to work around bad sites and legacy implementations,
	e.g. with a user style sheet rule like:
	<div class="example">
		Example: user preference
		<pre><code class="lang-css">input[type=password] {
			ime-mode: auto&nbsp;!important;
		}
		</code></pre>
	</div>

	This example CSS may be placed into a user style sheet file to force password input fields to behave in a default manner.

	This specification deliberately does not attempt
	to document the functionality of legacy ime-mode implementations
	nor what they specifically support because it does not make sense to pursue or recommend any such path.

	<div class="note">
		Note: there are several [[HTML5]] features which authors should use
		to provide information to user agents that allow them to provide a better input user experience:

		<ul>
			<li>The global <code>lang</code> attribute

			<li>The <code>inputmode</code>, <code>pattern</code>, and <code>type</code> attributes of the input element
		</ul>
	</div>


<h2 id="user-interaction">
User Interaction</h2>

<h3 id="content-selection">
Controlling content selection</h3>

	The 'user-select' property enables authors to specify
	which elements in the document can be selected by the user and how.
	This allows for easier interactions when not
	all elements are equally useful to select,
	avoiding accidental selections of neighboring content.

	<pre class='propdef'>
	Name: user-select
	Value: auto | text | none | contain | all
	Initial: auto
	Inherited: no
	Applies to: all elements, and optionally to the ''::before'' and ''::after'' pseudo-elements
	Computed value: specified keyword
	Animation type: discrete
	</pre>

	User agents must not apply the 'user-select' property to
	the ''::first-line'' and ''::first-letter'' pseudo-elements.

	Note: The UA may apply this property to the ''::before'' and ''::after'' pseudo-elements.
	If it does, the ''user-select/auto'' value maps to a [=used value=] of ''user-select/none'' on these pseudos,
	but other values can be specified.
	This preserves the legacy behavior of generated content not being selectable or copyable,
	which is appropriate when these pseudos are used for decorative purposes.
	However, this property allows them to become selectable and copyable,
	as the user would expect in cases where they are used to generate parts of the content,
	such as the issue numbers in this document.
	<strong class="advisement">To the extent possible,
	authors should avoid using generated content
	for non-decorative purposes,
	and should prefer including all the content in the DOM.</strong>
	<em>This feature is at risk.</em>

	Issue: if we allow user-select to change to a value other than ''user-select/none'',
	we need to figure out what this means for copyability and DOM APIs.

	When generated content in pseudo-elements becomes selectable
	through this mechanism,
	UAs should also make this content findable through their search function.

	Issue: Should it also apply to ''::marker''? To <a>page-margin boxes</a>?
	Should the [=used value=] of ''user-select/auto'' also be ''user-select/none'',
	or would ''user-select/text'' be more appropriate?

	The [=used value=] is the same as the [=computed value=],
	except:

	<ol>
		<li>
			on <a>editable element</a>s
			where the [=used value=] is always ''user-select/contain''
			regardless of the [=computed value=]

		<li>
			when the [=computed value=] is ''user-select/auto'',
			in which case the [=used value=] is one of the other values as defined below
	</ol>

	For the purpose of this specification,
	an <dfn>editable element</dfn> is either
	an <a href="https://w3c.github.io/contentEditable/#dfn-editing-host">editing host</a>
	or a <a spec=html>mutable</a> form control with textual content,
	such as <{textarea}>.

	Issue: Should there be constraints
	on what happens to the used value
	on elements that are editable descendants of editing hosts?
	The semantics are not obvious.
	Maybe ''user-select/none'' should map to ''user-select/text'',
	or maybe all values should map to ''user-select/text''.

	<dl dfn-type=value dfn-for=user-select>
		<dt><dfn>auto</dfn>
		<dd>
			The [=used value=] of ''user-select/auto'' is determined as follows:

			<ul>
				<li>
					On the ''::before'' and ''::after'' pseudo-elements,
					the used value is ''user-select/none''

				<li>
					If the element is an <a>editable element</a>,
					the [=used value=] is ''user-select/contain''

				<li>
					Otherwise,
					if the [=used value=] of 'user-select' on the parent of this element is ''all'',
					the [=used value=] is ''all''

				<li>
					Otherwise,
					if the [=used value=] of 'user-select' on the parent of this element is ''user-select/none'',
					the [=used value=] is ''user-select/none''
				<li>
					Otherwise, the [=used value=] is ''user-select/text''
			</ul>

			Note: This unusual combination of a non-inherited property with an initial value of ''user-select/auto''
			whose used value depends on the parent element
			makes it possible to create what is effectively selective inheritance.
			This was initially proposed by Microsoft in IE to introduce a behavior similar to inheritance,
			except that the ''user-select/contain'' value does not inherit.

		<dt><dfn>text</dfn>
		<dd>
			The element imposes no constraint on the selection.

		<dt><dfn caniuse="user-select-none">none</dfn>
		<dd>
			The UA must not allow selections to be started in this element.

			A selection started outside of this element must not end in this element.
			If the user attempts to create such a selection,
			the UA must instead end the selection range at the element boundary.

			Note: As of the time of writing, experimental implementations do not all behave like this.
			Firefox does.
			Chrome and Safari almost do: for a selection started after the element
			and trying to go backwards into the element,
			they behave as specified here,
			but for a selection started before the element
			and trying to go into the element,
			they behave as if the element has ''all'' and select it entirely.
			IE does not restrict selections started outside of the element
			from going into it at all.
			Another difference is that in Chrome and Safari,
			if the user attempts to start a selection inside a ''user-select: none'',
			and to end the selection out of it,
			a selection will be created from the boundary of the element
			to the user-designated end point.
			Firefox and Internet Explorer behave as prescribed in this specification
			and do not create a selection at all.

			However, if this element has descendants on which the [=used value=] of 'user-select' is not ''user-select/none'',
			selections that start and end within these descendants are allowed.

			The UA must allow selections to extend across this element,
			and must exclude this element from such a selection.
			An exception is made for UAs which do not support multiple ranges per selection,
			and they may include this element.
			If the element has descendants on which the [=used value=] of 'user-select' is not ''user-select/none'',
			these descendants must be included in a selection extending across the element.
			<span class=note>This specification makes no normative requirement
			about the behavior of the clipboard.
			However, UAs are encouraged to keep the visual selection consistent
			with what would get copied to the clipboard when copying.
			Copying text that does not appear to be selected, or vice versa,
			is highly confusing to users.</span>

			Attempting to start a selection in an element where 'user-select' is ''user-select/none'',
			such as by clicking in it or starting a drag in it,
			must not cause a pre-existing selection to become unselected or to be affected in any way.

			As 'user-select' is a UI convenience mechanism,
			not a copy protection mechanism,
			the UA may provide an alternative way for the user
			to explicitly select the text even when 'user-select' is ''user-select/none''.

			Note: ''user-select/none'' is not a copy protection mechanism,
			and using it as such is ineffective:
			user agents are allowed to provide ways to bypass it,
			it will have no effect on legacy user agents that do not support it,
			and the user can disable it through the user style sheet or equivalent mechanisms
			on UAs that do anyway.
			Instead, ''user-select/none'' is meant to
			make it easier for the user to select the content they want
			by letting the author disable selection on UI elements
			that are not useful to select.
			Tools such as CSS validators, linters, or in-browser developer tools
			are encouraged to use heuristics
			to detect and warn against incorrect or abusive usage
			that would hamper usability
			or violate common user expectations.

			<div class=note>
				Authors should be careful about not constraining the user unnecessarily.
				For example, setting ''user-select: none'' on the root element,
				and relaxing that restriction on a handful of elements the author judges useful to select can be frustrating to users:

				* Clicking in empty areas to undo the current selection will no longer be effective
				* The author may have overlooked some areas which should be selectable
				* Areas may be added later to the page without remembering to make them selectable
				* The user may want to select pieces of text other than the main content,
					for instance to look them up in a dictionary or in some translation tool,
					or to look for warnings and error messages in a search engine…

				Instead, a good practice is for authors is to selectively apply ''user-select: none'' to elements
				which seem likely to be accidentally selected
				when doing so would interfere with the more likely intended action.
				Accidentally leaving parts of the page that are unlikely to be interacted with selectable
				will likely cause much less frustration to users than the opposite.
			</div>

		<dt><dfn>contain</dfn>
		<dd>
			UAs must not allow a selection which is started in this element
			to be extended outside of this element.

			A selection started outside of this element must not end in this element.
			If the user attempts to create such a selection,
			the UA must instead end the selection range at the element boundary.

			The UA must allow selections to extend across this element,
			and such selections must include the content of the element.

			Note: At the time of writing, experimental implementations behave differently from each other
			about selections started outside and selections going into the element.
			The behavior can be observed even on browsers that do not explicitly support ''user-select/contain''
			by trying to select into a <{textarea}> or a contenteditable element.

			Note: This was initially introduced
			as an experimental feature in Internet Explorer,
			under the name <code>user-select: element</code>.

		<dt><dfn>all</dfn>
		<dd>
			The content of the element must be selected atomically:
			If a selection would contain part of the element,
			then the selection must contain the entire element including all its descendants.
			If the element is selected
			and the [=used value=] of 'user-select' on its parent is ''all'',
			then the parent must be included in the selection, recursively.

			If this element has descendants on which the [=used value=] of 'user-select' is not ''all''
			and if a selection is entirely contained in these descendants,
			then the selection is not extended to include this whole element.
	</dl>

	Note: Selections can include more than just text and extend over images, tables, videos, etc.
	The behavior when copying and pasting such selections is out of scope for this specification.

	The following additions are made to the UA stylesheet for HTML:
	<pre><code class="lang-css">
	button, meter, progress, select { user-select: none; }
	</code></pre>

	Issue: the list above is incomplete and needs to include
	at least the various button-like variants of <{input}>.

	For compatibility with legacy content,
	UAs that support 'user-select' must also support <dfn property>-webkit-user-select</dfn> as an alias.

	Note: The details of the aliasing mechanism is intentionally left up to the UA.
	Making ''-webkit-user-select'' a shorthand property of 'user-select'
	is known to be an effective approach,
	and new implementers should consider it.
	However, UAs supporting ''-webkit-user-select'' as an alias of 'user-select' through other means exist
	without adverse consequences to compatibility,
	so this specification allows flexibility.


<h3 id="pointer-events-control">
Exclusion from Hit-testing: the 'pointer-events' property</h3>

	Issue: While this property modifies the normal behavior of hit-testing,
	this normal <dfn>hit-testing</dfn> is currently not specified.
	There is broad interoperability about the seemingly obvious parts of this problem,
	but there are countless nuances and corner cases that would greatly benefit
	from a detailed specification.
	The CSS-WG would hugely appreciate
	help with writing such a specification.

	<pre class=propdef>
	Name: pointer-events
	Value: auto | none
	Initial: ''pointer-events/auto''
	Applies to: all elements
	Inherited: yes
	Percentages: N/A
	Computed value: specified keyword
	Canonical order: per grammar
	Animation type: by computed value type
	</pre>

	The 'pointer-events' property defines whether an element's boxes can be targeted by point pointer events.
	Values have the following meanings:

	<dl dfn-for=pointer-events dfn-type=value>
		<dt><dfn>auto</dfn>
		<dd>
			[=Hit-testing=] occurs normally.

		<dt><dfn>none</dfn>
		<dd>
			[=Hit-testing=] acts as if the boxes generated by the element
			(see [[CSS-DISPLAY-3]])
			were not there,
			effectively causing the element behind the ''pointer-events: none'' element
			to become the target of hit-testing-based events instead.

			Issue: The statement above needs to be qualified;
			for some purposes,
			hit-testing continues to take the element into account.
			For instance, clicking and dragging to start a text selection will continue to work as usual.
			What is the precise set of things for which hit-testing is affected by 'pointer-events'?

	</dl>

	''pointer-events: none'' does not inhibit  [[HTML#sequential-focus-navigation|sequential focus navigation]].

	Note: This ''pointer-events: none'' only excludes the element itself from [=hit-testing=],
	not the whole subtree.
	While this property propagates to descendants via inheritance,
	''pointer-events: auto'' can be specified on a descendant of a ''pointer-events: none'' element,
	and such an element will participate normally in [=hit-testing=].

	Note: Events that target a ''pointer-events: auto'' descendant of a ''pointer-events: none'' element
	can still be caught by event handlers on ''pointer-events: none'' ancestors
	of the targeted element during the bubbling or capturing phases
	(see [[DOM#events]]).

	Note: [[SVG2#PointerEventsProp]] defines a variant of this property for SVG elements,
	with more possible values.
	The effect of such values outside of SVG is currently not defined.

<h3 id="inertness">
Preventing All Interaction: the 'interactivity' property</h3>

<pre class=propdef>
Name: interactivity
Value: auto | inert
Initial: auto
Applies to: all elements
Inherited: yes
Percentages: N/A
Computed Value: as specified
Animation type: discrete
</pre>

The 'interactivity' property specifies whether an element and its [=flat tree=] descendants
(including [=text nodes=])
are [=inert=] or not.

<dl dfn-type=value dfn-for=interactivity>
	: <dfn>auto</dfn>
	:: The element's [=inert|inertness=] is determined by the [=host language=].
		<span class=note>(This will <em>usually</em> mean the element is not [=inert=].)</span>

	: <dfn>inert</dfn>
	:: The element is [=inert=].
</dl>

<div algorithm>
	When an [=/element=] or [=text node=] is <dfn export>inert</dfn>:

	* Hit-testing must act as if 'pointer-events' was ''pointer-events/none'',
		regardless of its actual value.
	* Text selection must act as if 'user-select' was ''user-select/none'',
		regardless of its actual value.
	* If the [=/element=] or [=text node=] is editable,
		it must behave as if it was non-editable.
	* The [=/element=] or [=text node=] should be ignored
		for the purposes of find-in-page and similar searching actions.

	User agents may allow the user 
	to override the restrictions on find-in-page and text selection.
</div>

Note: This property allows an author to force an element [=inert=],
but doesn't allow making an element *non*-[=inert=],
just deferring inertness to the host language.
For example, in HTML, while a modal dialog is being displayed,
the rest of the page is forced inert automatically,
regardless of the value of this property.
In general, host languages can make use of more information about the document
than CSS has easy access to
to determine what the best inertness behavior is for users.

Note: [=Inert=] nodes generally cannot be focused, 
and user agents do not expose the inert nodes 
to accessibility APIs or assistive technologies.
An inert subtree should not contain any content or controls 
which are critical to understanding or using aspects of the page 
which are not in the inert state. 
Content in an inert subtree will not be perceivable by all users, or interactive. 
Authors should not specify elements as inert 
unless the content they represent are also visually obscured in some way. 
In most cases, 
authors should not specify the inert attribute on individual form controls. 
In these instances, the <{input/disabled}> attribute is probably more appropriate.

<div class=issue>
	The following should be inserted into the HTML stylesheet,
	to ensure that top-level modal dialogs become uninert by default:

	<pre highlight=css>
	[inert] {
		interactivity: inert;
	}
	dialog:modal {
		interactivity: auto;
	}
	</pre>

	The <css>dialog:modal</css> selector above needs to be expanded 
	for any other elements that escape inertness by default.
</div>


<h3 id="interest">
User Interest Delay: the 'interest-delay-*' properties</h3>

	<pre class="propdef">
	Name: interest-delay-start, interest-delay-end
	Value: normal | <<time>>
	Initial: ''interest-delay/normal''
	Applies to: all elements
	Inherited: yes
	Percentages: n/a
	Computed value: the keyword ''interest-delay/normal'' or a computed time
	Canonical order: per grammar
	Animation type: by computed value type
	</pre>

	<pre class="propdef shorthand">
	Name: interest-delay
	Value: <<'interest-delay-start'>>{1,2}
	</pre>

	Some [=host language=] features
	can be activated when a user "shows interest" in an element.
	Exactly what this means is up to the [=host language=] and [=user agent=]
	(for example, the HTML <{html-global/interestfor}> attribute),
	but a common property of such features
	is that "interest" shouldn't be gained or lost <em>instantly</em>.

	For example, if "interest" can be shown by hovering the cursor over an element,
	briefly passing the cursor over the element
	while moving the cursor over the page
	should not (at least by default) indicate "interest"--
	that could result in UI confusingly popping up and disappearing
	while the user is performing unrelated tasks.

	Similarly, once interest has been shown,
	it should not (at least by default)
	<em>lose</em> interest instantaneously either.
	Again, as an example,
	if the user "shows interest" in a link by hovering the cursor over it,
	causing a child popup list to appear next to it,
	moving the cursor from the link to the popup
	likely involves briefly leaving both the link and the list,
	but shouldn't cause the list to "lose interest"
	and close the popup.

	The 'interest-delay' shorthand,
	and its 'interest-delay-start' and 'interest-delay-end' longhands,
	allow control of the <dfn export>interest start delay</dfn>
	and <dfn>interest end delay</dfn>
	for these features
	on a given element.
	Its possible values are:

	<dl dfn-type=value dfn-for="interest-delay, interest-delay-start, interest-delay-end">
		: <dfn>normal</dfn>
		:: The [=interest start delay=] and/or the [=interest end delay=]
			are UA-defined.
			They can be chosen to match platform conventions.

			These delays <em>should not</em> be zero.
			They <em>may</em> be different from each other,
			and may vary depending on the way the user is showing interest.
			(For example, a "hover" and a "long press"
			might use different delays for indicating interest.)

		: <dfn><<time>></dfn>
		:: Specifies that the [=interest start delay=] and/or the [=interest end delay=]
			are the specified duration.
	</dl>

	The 'interest-delay' shorthand
	sets 'interest-delay-start' to its first value,
	and 'interest-delay-end' to its second value
	(or to the first value, if only one value is passed).

	Note: In the future, the syntax of these properties might be expanded
	to allow for customizing the delay
	depending on feature
	and how the user is showing interest.
	(For example, providing different delays
	for hovering vs long-pressing.)


<h2 id="styling-widgets" oldids="form-styling, control-styling">
Styling Widgets</h2>

<h3 id="widget-accent">
Widget Accent Colors: the 'accent-color' property</h3>

	<pre class=propdef>
	Name: accent-color
	Value: auto | <<color>>
	Initial: ''accent-color/auto''
	Applies to: all elements
	Inherited: yes
	Percentages: N/A
	Computed value: the keyword ''accent-color/auto'' or a computed color
	Canonical order: per grammar
	Animation type: by computed value type
	</pre>

	User interface controls on any given platform are typically designed as a cohesive set,
	under a single, cohesive visual style.
	On many platforms (though not all),
	the visual style includes the use of an <dfn>accent color</dfn>,
	a typically bright color that contrasts markedly
	with the more utilitarian background and foreground colors.
	Not every control uses the [=accent color=] in every state,
	but it is nonetheless a core part of the controls’ color scheme.

	The 'accent-color' CSS property allows the author to specify the [=accent color=]
	for user-interface controls generated by the element.
	Values have the following meanings:

	<dl dfn-for=accent-color dfn-type=value>
		<dt><dfn>auto</dfn>
		<dd>
			Represents a UA-chosen color,
			which should match the [=accent color=] of the platform, if any.

		<dt><dfn><<color>></dfn>
		<dd>
			Specifies the color to be used as the [=accent color=].
	</dl>

	The UA should use the specified 'accent-color'
	to draw whichever parts of the element’s control(s)
	would have otherwise been styled with an [=accent color=].
	The UA must maintain contrast for legibility of the control,
	and in order to do so
	may adjust the luminance or brightness of the color
	or make color substitutions in other parts of the control
	(e.g. switching an overlaid glyph from using 'color' to using 'background-color').
	It may also generate variations of the color for gradients etc.
	to match the control to platform conventions for the use of the accent color.

	<div class="example">
		A radio button is typically composed of a circle,
		potentially overlaid by a “dot” representing the checked state.
		Certain visual styles use an [=accent color=] for the checked state:
		some of these use it for the background of the circle,
		others for its foreground.

		In both cases, the 'accent-color' property styles
		the affected parts of the control.
		For visual styles that do not use an [=accent color=] for radio buttons,
		'accent-color' will have no effect.

		The following are all examples of radio buttons
		conformantly rendered with a blue 'accent-color':

		<style>
		#accent-color-examples td:nth-child(2) { white-space: nowrap; }
		</style>
		<table class="data" id="accent-color-examples">
		<thead>
			<tr>
				<th>Platform
				<th>Sample
				<th>Notes
		<tbody>
			<tr>
				<td>Firefox 79 / Win
				<td><img src="images/radio-ff79-empty.png"
				         alt="Unchecked: white-filled black-stroked circle.">
				    <img src="images/radio-ff79-check.png"
				         alt="Checked: white-filled black-stroked circle with a filled black circle inside.">
				<td>No use of [=accent color=].
			<tr>
				<td>Chrome 81 / Win
				<td><img src="images/radio-c81-empty.png"
				         alt="Unchecked: light gray shaded circular bubble.">
				    <img src="images/radio-c81-check.png"
				         alt="Checked: light gray shaded circular bubble overlaid with a dark grey circle.">
				<td>No use of [=accent color=].
			<tr>
				<td>Safari / Snow Leopard
				<td><img src="images/radio-aqua-empty.png"
				         alt="Unchecked: uncolored 3D-looking glassy bubble.">
				    <img src="images/radio-aqua-check.png"
				         alt="Checked: light blue 3D-looking glassy bubble overlaid with a small black dot.">
				<td>Accent color used to generate checked-state “background” gradient.
			<tr>
				<td>Safari 13 / Mac / Light
				<td><img src="images/radio-s13L-empty.png"
				         alt="Unchecked: light gray inset-shadowed circle.">
				    <img src="images/radio-s13L-check.png"
				         alt="Checked: bright blue filled circle overlaid with a small, drop-shadowed white dot.">
				<td>Accent color as checked-state “foreground”.
			<tr>
				<td>Safari 13 / Mac / Dark
				<td><img src="images/radio-s13D-empty.png"
				         alt="Unchecked: dark gray circle shaded to look embossed but with a convex surface.">
				    <img src="images/radio-s13D-check.png"
				         alt="Checked: bright blue filled circle shaded to look embossed, overlaid with a small white dot.">
				<td>Accent color as checked-state “foreground”.
			<tr>
				<td>Chrome 83 / Win / Light
				<td><img src="images/radio-c83-empty.png"
				         alt="Unchecked: dark gray empty circle.">
				    <img src="images/radio-c83-check.png"
				         alt="Checked: bright blue stroked circle overlaid with concentric bright blue filled circle.">
				<td>Accent color as checked-state “foreground”.
			<tr>
				<td>Chrome 83 / Win / Dark
				<td><img src="images/radio-c86-empty.png"
				         alt="Unchecked: light gray circle filled with dark gray.">
				    <img src="images/radio-c86-check.png"
				         alt="Checked: bright powder-blue stroked circle overlaid with concentric powder-blue filled circle.">
				<td>Accent color as checked-state “foreground”, contrast-adjusted for dark mode backgrounds.
		</table>
	</div>

	If the color supplied is partially or fully transparent,
	the user agent must first pre-compose it over the ''<system-color>/Canvas'' system color
	and use the resulting (now opaque) color as the accent color.

	Note: Although it may vary based on user settings,
	''<system-color>/Canvas'' is typically white when in a [=light color scheme =]
	and black when in a [=dark color scheme=].

<h3 id="appearance-switching" caniuse="css-appearance">
Switching appearance: the 'appearance' property</h3>

	<pre class="propdef">
	Name: appearance
	Value: ''appearance/none'' | ''auto'' | ''base'' | ''base-select'' | <<compat-auto>> | <<compat-special>>
	Initial: none
	Applies To: all elements
	Inherited: no
	Computed value: specified keyword
	Animation type: discrete
	</pre>

	While the way most elements in a document look can be fully controlled by CSS,
	<a>widgets</a> are typically rendered by UAs using native UI controls of the host operating system,
	which can neither be replicated nor styled using CSS.

	The term <dfn export>widget</dfn> in this specification denotes [=replaced=] elements that can have <dfn export lt="native appearance|native render|natively render">native appearance</dfn>,
	meaning that they are rendered like analogous native widgets or controls of the host operating system or platform,
	or with a look and feel not otherwise expressible in CSS.
	It is up to the host language (e.g., HTML [[HTML]]) to define which elements can have <a>native appearance</a>.

	This specification introduces the 'appearance' property
	to provide some control over this behavior.
	In particular, using ''appearance: none'' allows authors
	to suppress the <a>native appearance</a> of <a>widgets</a>,
	giving them a <dfn export>primitive appearance</dfn>
	where CSS can be used to restyle them.

	Using ''appearance: base'' gives <a>widgets</a> a <dfn export>base
	appearance</dfn>. <a>Widgets</a> in <span>base appearance</span> have their
	<a>native appearance</a> suppressed where CSS can be used to restyle them,
	just like <a>primitive appearance</a>, but also have default styles which are
	usable and interoperable. This is unlike <a>primitive appearance</a> which
	can cause some <a>widgets</a> to disappear completely.

	A widget can have some style sheet associated with it and those styles can
	change based on whether the widget has a <span>base appearance</span>.
	<span>Native appearance</span> and <span>primitive appearance</span> should
	have the same styles.

	ISSUE: ''appearance:base'' is not ready to ship until its stylesheet has been
	fully defined in the HTML specification, and implemented accordingly for all
	HTML form controls.

	<details class=note>
		<summary>Note on the history of this feature</summary>

		This previously existed in prefixed form in most browsers.
		Before standardization, in addition to ''appearance/none'',
		the possible values were a very long list of all the ways an element could look;
		each value being responsible for giving form controls their specific look and feel.
		This list was different across browsers.

		The CSS Working Group concluded this was impractical to standardize,
		in part because many values applied to pseudo-elements that other browsers don't have,
		as they construct form elements differently,
		and which should not be standardized,
		since the ability to make form controls look substantially different on different platforms
		should be preserved.

		Also, the ability to turn any arbitrary element (including any form control)
		into any (other) arbitrary form control
		is considered a misfeature.

		Instead, the design being specified
		is based on just having an "auto" value that makes form controls look like whatever they need,
		and a "none" value that suppresses [=native appearance=].

		However, there is evidence that this alone is not web compatible,
		due in part to uses such as:
		<pre><code highlight=css>
		input { appearance: none; }
		input[type=checkbox] { appearance: checkbox; }
		</code></pre>

		The design specified here is a compromise between the two,
		preserving the simplicity of the ''none | auto'' model
		while maintaining compatibility with existing content
		via a few additional keywords.

		The precise list of keywords needed for compatibility
		and their exact behavior
		is likely to be refined in a future version of this specification
		to better handle compatibility with existing content.
		The CSS-WG welcomes relevant feedback.
	</details>

	<dl dfn-type=value dfn-for=appearance>
		<dt><dfn>none</dfn>
		<dd>
			The element is rendered following the usual rules of CSS.
			Replaced elements other than <a>widgets</a> are not affected by this
			and remain replaced elements.
			<a>Widgets</a> must not have their <a>native appearance</a>,
			and instead must have their <a>primitive appearance</a>.
			See [[#appearance-decorative]] and [[#appearance-semantics]] for details.

		<dt><dfn>auto</dfn>
		<dd>
		  The element's box is laid out like a regular replaced element. 

		  Within that box, elements representing <a>widgets</a> should have the <a>native appearance</a> of that widget.

		  The host language is responsible for defining
		  which elements represent which <a>widgets</a>.

		  Elements other than <a>widgets</a> must be rendered as for ''appearance/none''.

		<dt><dfn>base</dfn>
		<dd>
			The effect of ''appearance/base'' depends on the element it is applied to:
			<dl class=switch>
				: elements other than <a>widgets</a>
				:: Elements other than <a>widgets</a> must be rendered as for
					''appearance/none''.

				: <a>Widgets</a> which support <a>base appearance</a>
				:: Just like ''appearance/none'', the element is rendered following the
					usual rules of CSS. <a>Widgets</a> must not have their <a>native
					appearance</a>, and instead must have their <a>base appearance</a>.

				: <a>Widgets</a> which don't support <a>base appearance</a>
				:: <a>Widgets</a> which don't have a <a>base appearance</a> must be
					rendered as for ''appearance/auto''. The host language is responsible
					for defining which <a>widgets</a> have a <a>base appearance</a>.
			</dl>

		<dt><dfn>base-select</dfn>
			<dd>
				The effect of ''appearance/base-select'' depends on the element it is applied to:
				<dl class=switch>
					: The <{select}> element or ''::picker(select)''
					:: The element is rendered as for ''appearance/base''.

					: Everything else
					:: The element is rendered as for ''appearance/auto''.
				</dl>

		 <dt><dfn type="">&lt;compat-auto></dfn>
		 <dd>
			These values exist for compatibility of content developed
			for earlier non-standard versions of this property.
			They all have the same effect as ''appearance/auto''.

			<pre class=prod style="white-space: normal"><<compat-auto>> =  <dfn>searchfield</dfn> | <dfn>textarea</dfn> | <dfn>checkbox</dfn> | <dfn>radio</dfn> | <dfn>menulist</dfn> | <dfn>listbox</dfn> | <dfn>meter</dfn> | <dfn>progress-bar</dfn> | <dfn>button</dfn> </pre>

			Issue: When ''appearance/auto'' is widely supported,
			recommend using it instead.

			Issue: If any of these values are not needed for web compat,
			they should be dropped from this list;
			conversely, any value needed for compat not included in this list should be added.

			Issue: It is possible that for compat reasons
			some of these values need to be promoted to being full blown values
			with effects on arbitrary elements,
			or that
			some of these values need to have some side effects on some <a>widgets</a>.

		 <dt><dfn type="">&lt;compat-special></dfn>
		 <dd>
			These values exist for compatibility of content developed
			for earlier non-standard versions of this property.
			For the purpose of this specification,
			they all have the same effect as ''appearance/auto''.
			However, the host language may also take these values into account
			when defining the <a>native appearance</a> of the element.

			<pre class=prod style="white-space: normal"><<compat-special>> =  <dfn>textfield</dfn> | <dfn>menulist-button</dfn> </pre>

			<div class=example>
				For instance, in [[HTML]]:
				* The native appearance of <{input}> elements with a <code>"search"</code> <{input/type}> attribute changes
					to match the appearance of <{input}> elements with a <code>"text"</code> <{input/type}> attribute
					when 'appearance' is ''textfield''.
				* The native appearance of drop-down box <{select}> elements changes
					to match that of its <a>devolved</a> state
					when 'appearance' is ''menulist-button''.
			</div>

	</dl>

	<div class=issue>
		The values <code>slider-vertical</code> and <code>sliderthumb-vertical</code>
		are supported in some user agents to change the orientation of
		<code class="lang-markup">&lt;input type=range></code> elements.
		These values are not specified because changing the orientation of this control
		is better done with a separate mechanism.
		See issue <a href="https://github.com/whatwg/html/issues/4177">whatwg/html#4177</a>.
	</div>

	<div class=example>
		An author wanting to customize the look and feel of check boxes in HTML could use the following:
		<pre><code class="lang-css">
		input[type=checkbox] {
			all: unset; /* this shorthand includes resetting appearance to none */
			width: 1em;
			height: 1em;
			display: inline-block;
			background: red;
		}
		input[type=checkbox]:checked {
			border-radius: 50%;
			background: green;
		}
		input[type=checkbox]:focus-visible {
			outline: auto;
		}
		</code></pre>

		<code class="lang-markup">&lt;input type="checkbox"></code> would be rendered as
		<span style="display: inline-block; width: 1em; height: 1em; background: red;"></span>,
		while <code class="lang-markup">&lt;input type="checkbox" checked></code> would be rendered as
		<span style="display: inline-block; width: 1em; height: 1em; background: green; border-radius: 50%;"></span>,
		and activating (for example by clicking) the element would toggle the state as usual.
	</div>

	User agents may [=disregard=] some CSS properties used to size and paint the contents
	of [=widgets=] rendered with their [=native appearance=]
	to ensure that the intended appearance is preserved,
	or because these properties may not be meaningful for the chosen appearance.

	<dfn lt="disregard">Disregarding</dfn> a property means that
	the user agent treats it as if it didn't [=apply to=] the widget in question.
	Nevertheless,
	unless an explicit exception is specified (for compatibility reasons),
	the user agent must still determine the [=computed value=] of any [=disregarded=] property
	according to the usual rules.

	In more detail, the rules for disregarding properties for [=natively rendered=] widgets are:

	<ul>
		<li>CSS properties that impact the box sizing or position of the widget's box (such as the [=sizing properties=]),
			or their visual appearance outside of the box (such as 'transform', 'filter' or 'box-shadow'), must be applied to
			[=widgets=] rendered with their [=native appearance=]. The widget's box participates in the rest of layout like any other replaced element.
		<li> Properties that affect the internal box model sizing of the widget's box (such as 'box-sizing', 'padding', 'border' or 'margin') may be disregarded when needed.
		<li> Other properties that affect painting (like 'background-color') may be disregarded when needed.
		<li> User agents should take into account CSS properties that affect writing modes or font-related properties when possible,
	when rendering text within the widget.
		<li> The 'object-fit' property does not apply.
	</ul>

	<div class=example>
		Some user agents respect the 'border' and 'padding' CSS properties for a &lt;select&gt; rendered with [=native appearance=], but
		not for &lt;input type=checkbox&gt;.
	</div>

	Native rendering of widgets may overflow the size of its box if its intrinsic sizing exceeds that size.

	For compatibility with legacy content, UAs must also support <dfn property export>-webkit-appearance</dfn>
	as a [=legacy name alias=] of 'appearance'.


<h4 id="appearance-disabling-properties">
Properties Disabling Native Appearance</h4>

	Certain properties, when declared in the [=Author Origin=],
	will disable the [=native appearance=] of certain [=widgets=].
	Specifically,
	if all the declarations of the [=Author Origin=]
	pertaining to such a [=widget=] are cascaded
	and a [=cascaded value=] exists--
	after having rolled back any number ''revert'' or ''revert-layer'' values--
	for any <a>property that disables native appearance for widgets</a>,
	then that [=widget=] is rendered as a <a>devolved widget</a>.
	The rendering of a <dfn export lt="devolved|devolved widget">devolved widget</dfn>
	is identical to that of the [=widget=] in its [=primitive appearance=],
	except when specified otherwise by the host language.

	The host language defines
	which elements represent <dfn export lt="devolvable|devolvable widget">devolvable widgets</dfn>.
	Widgets whose appearance remains native
	regardless of any <a>properties that disable native appearance for widgets</a>
	are called <dfn export lt="non-devolvable|non-devolvable widget">non-devolvable widgets</dfn>.

	The <dfn lt="property that disables native appearance for widgets|properties that disable native appearance for widgets">properties that disable native appearance for widgets</dfn> are:
	<ul>
		<li>'background-color'
		<li>'border-top-color'
		<li>'border-top-style'
		<li>'border-top-width'
		<li>'border-right-color'
		<li>'border-right-style'
		<li>'border-right-width'
		<li>'border-bottom-color'
		<li>'border-bottom-style'
		<li>'border-bottom-width'
		<li>'border-left-color'
		<li>'border-left-style'
		<li>'border-left-width'
		<li>'border-block-start-color'
		<li>'border-block-end-color'
		<li>'border-inline-start-color'
		<li>'border-inline-end-color'
		<li>'border-block-start-style'
		<li>'border-block-end-style'
		<li>'border-inline-start-style'
		<li>'border-inline-end-style'
		<li>'border-block-start-width'
		<li>'border-block-end-width'
		<li>'border-inline-start-width'
		<li>'border-inline-end-width'
		<li>'background-image'
		<li>'background-attachment'
		<li>'background-position'
		<li>'background-clip'
		<li>'background-origin'
		<li>'background-size'
		<li>'border-image-source'
		<li>'border-image-slice'
		<li>'border-image-width'
		<li>'border-image-outset'
		<li>'border-image-repeat'
		<li>'border-top-left-radius'
		<li>'border-top-right-radius'
		<li>'border-bottom-right-radius'
		<li>'border-bottom-left-radius'
		<li>'border-start-start-radius'
		<li>'border-start-end-radius'
		<li>'border-end-start-radius'
		<li>'border-end-end-radius'
	</ul>


<h4 id=appearance-decorative>
Effects of 'appearance' on Decorative Aspects of Elements</h4>

	All decorative visual aspects of a <a>widget</a> which are not caused by a CSS style rule
	must be suppressed when the appearance is changed from [=native appearance|native=] to [=primitive appearance|primitive=] using 'appearance',
	even if the UA's internal representation for this element
	was composed of multiple elements or pseudo-elements combined together.

	<div class=example>
		For example, the [[HTML]] <{select}> element is often rendered with an arrow on the right side
		indicating that the list will be expanded if the element is clicked.
		If the computed value of 'appearance' on a <{select}> element is ''appearance/none'',
		this must disappear.
	</div>

	UAs should include in their user agent stylesheet style rules
	to give <a>widgets</a> a recognizable shape when 'appearance' is ''appearance/none''.

	Note: Authors may therefore need to override these UA style rules to get the styling
	they intended.

	<div class=advisement>
		Authors may find it convenient to use ''all: unset''
		to get fully unstyled <a>widgets</a>,
		which they can then style as they want without interference from the user agent's stylesheet.
		However, this also suppresses the focus indicators provided by the same UA stylesheet.
		In order to avoid damaging accessibility,
		authors who do so should restore a focus indicator,
		for instance, by using '':focus-visible { outline: auto; }''.
	</div>


<h4 id=appearance-semantics>
Effects of 'appearance' on Semantic Aspects of Elements</h4>

	When showing the [=primitive appearance=] of a [=widget=]
	or its [=devolved=] state,
	user agents must preserve aspects of the <a>widget</a>
	which are necessary to operate the <a>widget</a> with its original semantics.
	The UA may, however, give them a different look and feel
	as long as it remains possible to operate the <a>widget</a>.
	Aspects of a <a>widget</a> which are merely needed to observe the state the <a>widget</a> is in
	and are not needed to operate it
	should be suppressed as well
	when the same information can be conveyed using ordinary CSS.
	Document languages should specify
	for each <a>widget</a> that they define
	what needs to be preserved.

	<div class=example>
		For example,
		the slider of an <code class="lang-markup">&lt;input type=range></code> is preserved
		(or replaced by an equivalent mechanism)
		even if 'appearance' is ''appearance/none'',
		as it would otherwise not be possible to change the value of the range with the mouse or touchscreen.

		On the other hand,
		the check mark in an <code class="lang-markup">&lt;input type=checkbox checked></code>
		must be suppressed,
		as it merely indicates the state the element is in,
		which can be styled in different ways using the '':checked'' selector.
	</div>

	The behavior and semantics of elements remain defined by the document language,
	and are not influenced by this property.

	<div class=example>
		For example, regardless of the computed value of 'appearance':

		<ul>
			<li>
				Elements which can be in different states keep this ability,
				and the relevant pseudo-classes match as usual.

				<li>
					If a <{select}> element is activated,
					the UI to choose one of the associated <{option}> elements is shown
					(although it may look different).

				<li>
					Event handlers attached to the element trigger as usual.
		</ul>
	</div>

	Conversely, changing the appearance of an element must not cause it
	to acquire the semantics, pseudo-classes, event handlers, etc.
	that are typical of the element whose appearance it acquires.

	<div class=example>
		For example, neither '':enabled'' nor '':disabled'' match on
		a <{div}> styled with ''appearance: button''.
		The ability for an element to be focused
		is also not changed by the 'appearance' property.
	</div>


<h3 id=control-specific-rules>
Control-Specific Rules</h3>

	Issue: Maybe some or all of this section
	should be moved to the [[HTML]] spec.
	at some point.

	Issue: On some elements, setting some properties inhibits ''appearance: auto''.
	For instance, even if 'appearance' is ''appearance/auto'',
	buttons lose their native appearance when a 'border' is set.
	This is not in contradiction with the definition of ''appearance/auto'',
	since ''appearance: auto'' only means
	UAs <em>may</em> use a native appearance,
	but for greater interoperability,
	it would be good to document
	which properties on which elements
	have this effect.

	Issue: Documenting what UAs need to put in their UA stylesheet would be good.


<h4 id=input-rules>
Single-Line Text Input Controls</h4>

	When 'appearance' is ''appearance/auto'',
	single-line text input controls
	such as [[!HTML]] <code highlight=html>&lt;input type=text></code>
	must be rendered so that:

	* The content is clipped in the inline direction to the <a>content edge</a>
	* The content is clipped in the block direction to the <a>padding edge</a>
	* The content is vertically centered
	* The content does not wrap
	* The 'text-overflow' property applies regardless of the value of the 'overflow' property


<hr title="Separator from footer">


<h2 class="no-num" id="acknowledgments">
Appendix A. Acknowledgments</h2>

	This appendix is <em>informative</em>.

	This specification builds upon [[CSS-UI-3]],
	which was edited and written for the most part
	by Tantek Çelik from 1999 to the present,
	first while representing Microsoft, then as an Invited Expert,
	and most recently while representing Mozilla.

	Thanks to feedback and contributions from
	<span class="h-card">Rossen Atanassov</span>,
	<span class="h-card">Tab Atkins</span>,
	<span class="h-card">L. David Baron</span>,
	<span class="h-card">Bert Bos</span>,
	<span class="h-card">Matthew Brealey</span>,
	<span class="h-card">Rick Byers</span>,
	<span class="h-card">Ada Chan</span>,
	<span class="h-card">James Craig</span>,
	<span class="h-card">Michael Cooper</span>,
	<span class="h-card">Axel Dahmen</span>,
	<span class="h-card">Michael Day</span>,
	<span class="h-card">Micah Dubinko</span>,
	<span class="h-card">Elika E.</span>,
	<span class="h-card">Steve Falkenburg</span>,
	<span class="h-card">Andrew Fedoniouk</span>,
	<span class="h-card">Al Gilman</span>,
	<span class="h-card">Ian Hickson</span>,
	<span class="h-card">Bjoern Hoehrmann</span>,
	<span class="h-card">Alan Hogan</span>,
	<span class="h-card">David Hyatt</span>,
	<span class="h-card">Richard Ishida</span>,
	<span class="h-card">Sho Kuwamoto</span>,
	<span class="h-card">Yves Lafon</span>,
	<span class="h-card">Stuart Langridge</span>,
	<span class="h-card">Susan Lesch</span>,
	<span class="h-card">Peter Linss</span>,
	<span class="h-card">Kang-Hao Lu</span>,
	<span class="h-card">Masayuki Nakano</span>,
	<span class="h-card">Mats Palmgren</span>,
	<span class="h-card">Brad Pettit</span>,
	<span class="h-card">Chris Rebert</span>,
	<span class="h-card">François Remy</span>,
	<span class="h-card">Andrey Rybka</span>,
	<span class="h-card">Simon Sapin</span>,
	<span class="h-card">Alexander Savenkov</span>,
	<span class="h-card">Sebastian Schnitzenbaumer</span>,
	<span class="h-card">Lea Verou</span>,
	<span class="h-card">Etan Wexler</span>,
	<span class="h-card">David Woolley</span>,
	<span class="h-card">Frank Yan</span>,
	<span class="h-card">Boris Zbarsky</span>,
	and
	<span class="h-card">Domel</span>.


<h2 class="no-num" id="changes">
Appendix B. Changes</h2>

	This appendix is <em>informative</em>.


<h3 id=changes-2021-03-16 class=no-num>
Changes from the <a href="https://www.w3.org/TR/2021/WD-css-ui-4-20210316/">16 March 2021 Working Draft</a></h3>

	In addition to a number of editorial adjustments,
	the following normative changes have been made:

	<ul>
		<li>
			Introduced a definition for the 'pointer-events' property.

		<li>
			Extend the image types required to be supported for the 'cursor' property
			from just <<url>> to <<url>> and <<url-set>>.
			(Support for the broader <<image>> type remains allowed but optional.)

		<li>
			Added <<image-1D>> as value for the 'outline-color' property.

		<li>
			Retired the <code>invert</code> value of 'outline-color'.

		<li>
			Added the ''outline-color/auto'' value of 'outline-color'.

		<li>
			Added 'field-sizing' property.

		<li>
			Removed claims that 'outline-width' may influence the rendering
			of ''outline-style: auto'' outlines.
			(See <a href="https://github.com/w3c/csswg-drafts/issues/9201">Issue 9201</a>.)

		<li>
			Moved 'field-sizing' and 'input-security' properties to css-forms-1.
	</ul>


<h3 id=changes-24-1-2020 class=no-num>
Changes from the <a href="https://www.w3.org/TR/2020/WD-css-ui-4-20200124/">24 January 2020 Working Draft</a></h3>

	In addition to a number of editorial adjustments,
	the following normative changes have been made:

	<ul>
		<li>
			Changed appearance: button to only apply to buttons.

		<li>
			Outline-width may be ignored if outline-style is auto.

		<li>
			Ensured caret visibility despite transforms.

		<li>
			Moved ''resize: block'' and ''resize: inline'' from css-logical-1 to this specification.

		<li>
			Introduced the 'accent-color' property.
	</ul>


<h3 id=changes-2-1-2020 class=no-num>
Changes from the <a href="https://www.w3.org/TR/2020/WD-css-ui-4-20200102/">2 January 2020 Working Draft</a></h3>

	In addition to a number of editorial adjustments,
	the following normative changes have been made:

	<ul>
		<li>
			Defined user-select to be discretely animatable, rather than not.

		<li>
			Restricted the applicability of ''appearance: button''
			so that it can no longer give a buttony appearance
			to widgets that aren't buttons to start with.

		<li>
			Add a clause to preserve visibility of carets even when scaled down via transforms.
	</ul>


<h3 id=changes-22-12-2017 class=no-num>
Changes from the <a href="https://www.w3.org/TR/2017/WD-css-ui-4-20171222/">22 December 2017 Working Draft</a></h3>

	In addition to a number of editorial adjustments,
	the following normative changes have been made:

	<ul>
		<li>Added details about form control-specific rendering rules
		<li>Clarify interaction between text-overflow and anonymous block containers
		<li>Require the ''cursor/pointer'' cursor for hyperlinks in all document formats
		<li>Moved the 'box-sizing' and 'text-overflow' properties to [[CSS-SIZING-3]] and [[CSS-OVERFLOW-4]] respectively.
		<li>Changed the requirement that the ''cursor/text'' cursor matches the writing mode from MAY to MUST
		<li>The definition of the appearance property has been significantly reworked to make the design compatible with existing web content
		<li>The logic that mapped ''user-select: auto'' to various values at computed value time has been changed to used value time
		<li>Clarify Author requirements on the ''cursor: pointer'' value
	</ul>


<h3 id=changes-22-09-2015 class=no-num>
Changes from the <a href="https://www.w3.org/TR/2015/WD-css-ui-4-20150922/">22 Sep 2015 First Public Working Draft</a></h3>

	In addition to a number of editorial adjustments,
	the following normative changes have been made:

	<ul>
		<li>
			The caret-animation property have been removed.
			It may be reintroduced later given sufficient evidence for use cases.

		<li>
			The ''resize'' property now also applies to
			replaced elements representing images or videos,
			and to iframes.

		<li>
			The string values and dual values of the text-overflow property were moved to this specification from level 3.

		<li>
			Move directional focus navigation properties from level 3 to level 4

		<li>
			Content from the now-stable [[CSS-UI-3]] has been merged in.
	</ul>


<h2 class="no-num" id="security-privacy-considerations">
Appendix C. Considerations for Security and Privacy</h2>

	This appendix is <em>informative</em>.

	The W3C TAG is developing a
	<a href="https://w3ctag.github.io/security-questionnaire/">Self-Review Questionnaire: Security and Privacy</a>
	for editors of specifications to informatively answer.

	Per the <a href="https://w3ctag.github.io/security-questionnaire/#questions">Questions to Consider</a>

	<dl>
		<dt>Does this specification deal with personally-identifiable information?
		<dd>No.

		<dt>Does this specification deal with high-value data?
		<dd>No.

		<dt>Does this specification introduce new state for an origin that persists across browsing sessions?
		<dd>No.

		<dt>Does this specification expose persistent, cross-origin state to the web?
		<dd>No.

		<dt>Does this specification expose any other data to an origin that it doesn’t currently have access to?
		<dd>No.

		<dt>Does this specification enable new script execution/loading mechanisms?
		<dd>
			Yes to loading, but not to execution.

			The 'cursor' property accepts <<image>> values which may include URLs to be loaded.
			These may be SVG documents which may contain scripts,
			but this specification requires that scripts must not be run.

		<dt>Does this specification allow an origin access to a user’s location?
		<dd>No.

		<dt>Does this specification allow an origin access to sensors on a user’s device?
		<dd>
			Yes.

			The directional focus navigation properties indirectly allow access to the device's keyboard navigation input mechanism such as arrow keys.

		<dt>Does this specification allow an origin access to aspects of a user’s local computing environment?
		<dd>No.

		<dt>Does this specification allow an origin access to other devices?
		<dd>No.

		<dt>Does this specification allow an origin some measure of control over a user agent’s native UI?
		<dd>
			Yes.

			The 'cursor' and 'caret' property and <a>sub-properties</a>
			enable the page to change the display of the cursor and text insertion caret of the user agent’s native UI.
			In addition the 'outline-style' property’s ''outline-style/auto'' value
			(and thus 'outline' shorthand)
			enable the page to potentially display a native focused element outline presentation around any element.

			The 'appearance' property also allows author to turn off native styling and replace it with css based styling.

		<dt>Does this specification expose temporary identifiers to the web?
		<dd>No.

		<dt>Does this specification distinguish between behavior in first-party and third-party contexts?
		<dd>No.

		<dt>How should this specification work in the context of a user agent’s "incognito" mode?
		<dd>No differently.

		<dt>Does this specification persist data to a user’s local device?
		<dd>No.

		<dt>Does this specification have a "Security Considerations" and "Privacy Considerations" section?
		<dd>Yes.

		<dt>Does this specification allow downgrading default security characteristics?
		<dd>No.
	</dl>


<h2 class="no-num" id="default-style-sheet">
Appendix D. Default style sheet additions for HTML</h2>

	This appendix is <em>informative</em>.

	Potential additions to the base style sheet to express HTML form controls, and a few dynamic presentation attributes:

	<pre class="lang-css">
	:enabled:focus {
		outline: 2px inset;
	}

	button,
	input[type=button],
	input[type=reset],
	input[type=submit],
	input[type=checkbox],
	input[type=radio],
	textarea,
	input,
	input[type=text],
	input[type=password],
	input[type=image] {
		display: inline-block;
	}

	input[type=button],
	input[type=reset],
	input[type=submit],
	input[type=checkbox],
	input[type=radio],
	input,
	input[type=text],
	input[type=password],
	input[type=image] {
		white-space: nowrap;
	}

	button {
		/* white space handling of BUTTON tags in particular */
		white-space:normal;
	}

	input[type=reset]:lang(en) {
		/* default content of HTML input type=reset button, per language */
		content: "Reset";
	}

	input[type=submit]:lang(en) {
		/* default content of HTML input type=submit button, per language */
		content: "Submit";
	}

	/* UAs should use language-specific Reset/Submit rules for others. */

	input[type=button],
	input[type=reset][value],
	input[type=submit][value] {
		/* text content/labels of HTML "input" buttons */
		content: attr(value);
	}

	textarea {
		/* white space handling of TEXTAREA tags in particular */
		white-space:pre-wrap;
		resize: both;
	}

	input[type=hidden] {
		/* appearance of the HTML hidden text field in particular */
		display: none !important;
	}

	input[type=image] {
		content: attr(src,url);
		border: none;
	}

	select[size] {
		/* HTML4/XHTML1 &lt;select&gt; w/ size more than 1 - appearance of list */
		display: inline-block;
		height: attr(size,em);
	}

	select,select[size=1] {
		/* HTML4/XHTML1 &lt;select&gt; without size, or size=1 - popup-menu */
		display: inline-block;
		height: 1em;
		overflow: hidden;
	}

	select[size]:active {
		/* active HTML &lt;select&gt; w/ size more than 1 - appearance of active list */
		display: inline-block;
	}

	optgroup, option {
		display: block;
		white-space: nowrap;
	}

	optgroup[label],option[label] {
		content: attr(label);
	}

	option[selected]::before {
		display: inline;
		content: check;
	}

	/* Though FRAME resizing is not directly addressed by this specification,
	   the following rules may provide an approximation of reasonable behavior. */

	/*

	frame { resize:both }
	frame[noresize] { resize:none }

	*/

	</pre>