Comparison of browser engines (CSS support)

This article compares Cascading Style Sheets (CSS) support for several browser engines.

Explanation of the tables

Engine	Status	Embedded in
WebKit	Active	Safari browser, plus all browsers hosted on the iOS App Store.
Blink	Active	Google Chrome and other web browsers based on Chromium, such as Microsoft Edge, Opera, and Brave.
EdgeHTML	Maintained	Universal Windows Platform apps; formerly in the Edge browser [1] .
Gecko	Active	Firefox browser and Thunderbird email client, plus forks like SeaMonkey and Waterfox.
KHTML	Maintained	Konqueror browser
Presto	Discontinued	Formerly used as Opera's browser engine, prior to the migration to Chromium and Blink.
MSHTML (Trident)	Maintained	Internet Explorer and versions of Microsoft Outlook prior to Outlook 2007.

Values

These indicate the level of support for the given item in each engine. By default, the most recent version of the engine is implied. However, a specific version number can be listed; when this indicates full support, it's the initial version of the engine fully supporting the item.

Legend

Value	Meaning
Yes	Fully supported
No	Has never been supported
Partial	Only some values are supported
Incorrect	Not implemented correctly in all cases
Experimental	May be incomplete or buggy
Nightly build	Currently in development; full support is expected
Depends	Only supported for the specified conditions
Dropped	No longer supported

Other notes

Vendor-specific

The DOM properties corresponding to vendor-specific experimental CSS properties are prefixed with the vendor-prefix, without any hyphens, and with first letters capitalised, e.g. element.style.MozBorderRadius corresponding to the -moz-border-radius property, or element.style.OTransform corresponding to the -o-transform property. The exception is MSHTML, which used a lower-case prefix, e.g. element.style.msTransform.

• Gecko: -moz-— All experimental selectors, properties and values are prefixed with "-moz-", e.g. ::-moz-selection instead of ::selection.
• Webkit: -webkit-— All experimental selectors, properties and values are prefixed with "-webkit-", e.g. -webkit-box-shadow instead of box-shadow.
• MSHTML: -ms-— All experimental properties are prefixed with "-ms-", e.g. -ms-interpolation-mode instead of interpolation-mode.
• KHTML: -khtml-— All experimental selectors, properties and values are prefixed with "-khtml-", e.g. -khtml-opacity instead of opacity.
• Presto: -o-— All experimental properties are prefixed with "-o-", e.g. -o-transition-property instead of transition-property.

Abbreviations

• CSS1 : Cascading Style Sheets (CSS1) Level 1 Specification ^{[spec 1]}
• CSS2 : Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification ^{[spec 2]}
• CSS3 : CSS Module Level 3
• CSS4 : CSS Module Level 4

Grammar and rules

			MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
CSS2	!important	Weight increasing	7.0	12	1.0	85	Yes	1.0
	/*Comment*/	Comments	3.0	12	1.0	85	Yes	1.0
	@import	Import stylesheet	8.0	12	1.0	Yes	Yes	1.0
	@charset	Character set	5.5	12	1.0	Yes	4.2.3	1.0
	@media	Media-specific rules	5.5	12	1.0	Yes	Yes	1.0
css- namespace-3	@namespace	Namespace declaration	9.0 [t 1]	12	1.0	Yes	Yes	1.0
earlier draft of css3- conditional	@document	Restriction by URLs	No	No	6.0	No	No	No
css- animations-1	@keyframes	Animation key	10.0 [t 2]	12	16.0	Experimental	No	2.12
css- conditional-3	@supports	Conditional Rules	No	12	22.0 [g 1]	28.0 [w 1]	No	2.12
css-counter- styles-3	@counter-style	Custom Counter Styles	No	No	33.0 [g 2]	No	No	No
css-device- adapt-1	@viewport	Viewport, Device Adaptation	10.0 [t 3]	12.0	No [w 2]	No	No	2.7.62 [p 1]
filter- effects-1	@filter	Filter	No	No	35.0	Experimental	No	No
Page
CSS2	@page	For paged media	8.0	12	19.0 [g 3]	Nightly Build [w 3]	No	1.0
css-page-3	@top-left-corner	Margin boxes [spec 3]	No	No	No	No [w 4]	No	No
	@top-left
	@top-center
	@top-right
	@top-right-corner
	@bottom-left-corner
	@bottom-left
	@bottom-center
	@bottom-right
	@bottom-right-corner
	@left-top
	@left-middle
	@left-bottom
	@right-top
	@right-middle
	@right-bottom
Font
css-fonts-3	@font-face	Define font	9.0 [t 4]	12	1.9.1	525	4.3	2.2
	@font-feature-values	Define font features	No	No	34.0	No	No	No
	@annotation	Font feature value block
	@styleset		No	No		No	No	No
	@swash		No	No		No	No	No
	@ornaments		No	No		No	No	No
	@stylistic		No	No		No	No	No
	@character-variant		No	No		No	No	No
			MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto

MSHTML notes

1. !important— Prior to 7.0, !important doesn't override rules defined later in the same declaration block.
2. @import— Prior to 8.0, media type support is broken. For @import <URL><MEDIA>, IE requests as the URL "<URL><MEDIA>" and will include the url() token and/or quotes in the URL, too, if present. Cannot import more than 35 stylesheets.

Presto notes

1. @import— Whilst Gecko, WebKit and iCab download all media stylesheets immediately, Opera only downloads handheld, print, projection and screen media, as well as speech if "voice" feature is enabled and TV, on TV devices. Text browser emulation mode is only a user stylesheet, so it does not switch to tty media type. This is consistent with older text browsers, which do not respect any CSS.

Selectors

			MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
Element selectors [spec 4]
CSS2	*	Universal	7.0	12	1.0	85	Yes	1.0
	E	Element	4.0	12	1.0	85	Yes
	E.class	Class	7.0	12	1.0	85	Yes
	E#id	ID	4.0	12	1.0	85	Yes
selectors-3	ns|E	Namespaced	9.0	12	1.0	Yes	Yes
Relationship selectors
CSS2	E F	Descendant	4.0	12	1.0	85	Yes	1.0
	E > F	Child	7.0	12	1.0	85	Yes
	E + F	Direct adjacent	7.0	12	1.0	85	Yes
selectors-3	E ~ F	Indirect adjacent	7.0	12	1.7	412	3.3.2	2.0
selectors-4	E /for/ F	Reference combinators	No	No	No	No	No	No
	E! > F	Subject	No	No	No [g 4]	No	No	No
	F || E	Column relation	No	No	No	No	No	No
Attribute selectors
CSS2	E[attr]	Has	7.0	12	1.0	85	Yes	1.0
	E[attr="value"]	Equals	7.0	12	1.0	Yes	Yes
	E[attr~="value"]	Contains (space-separated)	7.0	12	1.0	Yes	Yes
	E[attr|="value"]	Contains (hyphen-separated)	7.0	12	1.0	Yes	Yes
selectors-3	E[attr^="value"]	Begins with	7.0	12	1.0	Yes	3.4	1.0
	E[attr$="value"]	Ends with	7.0	12	1.0	Yes	3.4	2.0
	E[attr*="value"]	Contains substring	7.0	12	1.0	Yes	3.4
	E[ns|attr]	Namespaced	7.0	12	1.0	Yes	3.4
selectors-4	E[foo="bar" i]	Case-sensitivity	No	No	No	No	No	No
Pseudo-classes
CSS2	E:link	Unvisited hyperlink	3.0	12	1.0	85	Yes	1.0
	E:visited	Visited hyperlink	3.0	12	1.0	85	Yes
	E:active	Active	8.0	1.0	12	85	Yes
	E:hover	Mouseover	7.0	12	1.0	419.3	Yes
	E:focus	Focused	8.0	12	1.0	Yes	Yes
	E:first-child	First child	7.0	12	1.0	85	Yes
	E:lang()	Language	8.0	12	1.2	525	3.4
	@page:first	First page	8.0	12	No [g 5]	Yes [w 5]	No
	@page:left	Left page
	@page:right	Right page
selectors-3	E:root	Root	9.0	12	1.0	85	3.4	2.1
	E:not()	Negation
	E:empty	Empty			1.8	412
	E:first-of-type	First child of type			1.9.1	525
	E:last-child	Last child			1.0
	E:last-of-type	Last child of type			1.9.1
	E:only-child	Only child			1.8
	E:only-of-type	Only child of type			1.9.1
	E:nth-child	Nth child			1.9.1
	E:nth-last-child	Nth last child			1.9.1
	E:nth-of-type	Nth child of type			1.9.1
	E:nth-last-of-type	Nth last child of type			1.9.1
	E:target	Target			1.3			2.5
	E:enabled	Enabled state			1.8			2.0
	E:disabled	Disabled state			1.8
	E:checked	Checked state			1.0
selectors-4	E:indeterminate	Indeterminate state			1.9.2	522	No	No
	E:default	Default	No	No	1.9	Yes [w 6]	4.3	2.0
	E:valid	Valid	10.0 [t 5]	12	1.8	Yes [w 7]	No
	E:invalid	Invalid	10.0 [t 6]	12
	E:in-range	In range	No	13		Yes [w 8]
	E:out-of-range	Out of range	No	13
	E:required	Required	10.0 [t 7]	12	2.0 [g 6]	Yes [w 9]
	E:optional	Optional	10.0 [t 8]	12
	E:read-only	Read-only	No	13	78 [g 7]	530	Incorrect	Incorrect
	E:read-write	Read and write	No	13
	E:not(s1, s2)	Negations	No	No	84	No	No	No
	E:is(s1, s2)	Matches-any			82 [g 8]
	E:has(s1)	Relational pseudo-class			No
	E:dir(ltr)	Directionality			49 [g 9]
	E:lang(zh, *-hant)	Languages			No
	E:any-link	Hyperlink			50.0 [g 10]
	E:local-link	Local link			No
	E:local-link(0)	Local link
	E:scope	Contextual reference			32 [g 11]
	E:current	Time-dimensional : current			No
	E:current(s)	Time-dimensional : current
	E:past	Time-dimensional : past
	E:future	Time-dimensional : future
	E:nth-match(n of selector)	Nth child of
	E:nth-last-match(n of selector)	Nth last child of
	E:column(selector)	Column
	E:nth-column(n)	Nth column
	E:nth-last-column(n)	Nth last column
	E:placeholder-shown	placeholder text
	E:active-drop	will receive the item
	E:valid-drop	could receive the item
	E:invalid-drop	cannot receive the item
Pseudo-elements
CSS2	E:first-letter	First letter	9.0	12	1.0	85	Yes	1.0
	E:first-line	First line				Partial
	E:before	Before	8.0		1.9.1	Partial
	E:after	After
selectors-3	E::before	Double colon notation	9.0	12	1.9.1	Partial	3.4	1.0
	E::after	Double colon notation
	E::first-letter	Double colon notation			1.5	85
	E::first-line	Double colon notation				Partial
css-pseudo-4	E::marker [spec 5]	list marker	No	No	68	No	No	No
	E::selection	Selection	9.0	12	62	412	3.4	2.1
CSS UI pseudo elements	E::value	user interface element fragments [spec 6]	No	No	No	No	No	No
	E::choices
	E::repeat-item
	E::repeat-index
			MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto

General notes

1. :read-only and :read-write— Both Presto and KHTML handle the case of the contenteditable attribute incorrectly.

MSHTML notes

1. :active— Prior to 8.0, :active is only supported on anchor elements.
2. :hover— Prior to 7.0, :hover is only supported on anchor elements.
3. .one.two— Prior to 7.0, only .two class selector was taken into consideration.
4. *— Prior to 7.0 this was treated as a single or no element.
5. [attr]— Matches every td and th in a table when the attribute is colspan (regardless of whether any actually have a colspan attribute). ^{[t 9]} This may not actually be a bug, as ambiguity exists in the specification. ^{[t 10]}
6. :first-letter, :first-line— Prior to IE9 in 6.0, combining :first-letter rules with others may be problematic. ^{[t 11]} In 8.0, rules with !important are ignored inside :first-line and :first-letter declarations. ^{[t 12]}

Gecko notes

1. (:):before, (:):after— CSS2.0 behavior : some properties are unimplemented prior to 1.9.1. ^{[g 12]}

WebKit notes

1. :lang()— Only detected when explicitly present on element being tested, attribute not inherited.
2. (:):first-line—text-transform doesn't apply with this pseudo-element. ^{[w 10]}
3. (:):before/after— some styles can't be applied to :before and :after pseudo-elements, such as animations and transitions. ^{[w 11]}

Presto notes

1. :target— Prior to 2.5, styles aren't applied when navigating using back and forward buttons.

Properties

		MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
Cascading and Inheritance
css- cascade-3	all	No	No	27.0 [g 13]	No	No	No
Display
CSS2	display	8.0	12	1.9	85	Yes	1.0
Earlier draft of css- display-3	display-inside	No	No	No	No	No	No
	display-outside
	display-list
css- display-3	box-suppress
Box Model [spec 7]
CSS2	margin	9.0	12	1.0	85	Yes	1.0
	padding	4.0		1.0	85	Yes
	width	4.0		1.0	85	Yes
	height	4.0		1.0	85	Yes
	float	5.0		1.0	85	Yes
	clear	5.0		1.0	85	Yes
	min-width	7.0		1.0	Partial	Yes
	max-width	7.0		1.0	Partial	Yes
	min-height	7.0		1.7	Partial	3.3.2
	max-height	7.0		1.7	Partial	3.3.2
	visibility	9.0		1.8	Partial	Partial	2.5
Overflow
CSS2	overflow	9.0	12	1.0	85	3.2	1.0
css- overflow- 3	overflow-x	9.0	12	1.8	525	3.5.6	2.1
	overflow-y
	max-lines	No	No	No	No	No	No
Borders
CSS2	border	4.0	12	1.0	85	Yes	1.0
	border-color	7.0
	border-style	8.0
	border-width	4.0
	border-top	5.5
	border-right
	border-bottom
	border-left
css- backgrounds-3	border-radius	9.0 [t 1]	12	2.0 [g 14]	533 [w 12]	Experimental	2.5
	border-image	11.0		15.0 [g 15]	Experimental	No	2.5
	border-image-source			15.0 [g 16]	No		No
	border-image-slice
	border-image-width
	border-image-outset
	border-image-repeat
	box-shadow	9.0 [t 13]		2.0 [g 17] [g 18]	Yes [w 13]	No	2.5
	box-decoration-break	No	No	32.0 [g 19]	No [w 14]	No	2.7 [p 2]
		MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
Line Layout [spec 8]
CSS2	line-height	4.0	12	1.0	85	Yes	1.0
	vertical-align	8.0		1.0	85	Yes
Positioning
CSS2	position	7.0	12	1.0	85	Yes	1.0
	top	8.0		1.0	85	Yes
	right	8.0		1.0	85	Yes
	bottom	8.0		1.0	85	Yes
	left	8.0		1.0	85	Yes
	z-index	8.0		1.9	85	Yes
Box Alignment Module
css-align-3
	align-content	11.0	12	28.0	Experimental	No	No
	align-items			20.0
	align-self
	justify-content
	justify-items	No		No	No
	justify-self
Generated and Replaced Content [spec 9]
CSS2	quotes	8.0	12	Yes	412 [w 15]	3.4	1.0
	content	9.0 [t 14]		1.9	Partial	Yes	2.7
	counter-increment	8.0		1.8	525	3.4	1.0
	counter-reset	8.0		1.8	525	3.4
Lists [spec 10]
CSS2	list-style	4.0	12	1.0	85	Yes	1.0
	list-style-image	4.0		1.0	85	Yes
	list-style-position	4.0		1.0	85	Yes
	list-style-type	8.0		1.0	85	3.4
Colors
CSS2	color	3.0	12	1.0	85	Yes	1.0
css-color-3	opacity	9.0 [t 1]	12	1.7	125	4.0	2.0
		MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
Backgrounds
CSS2	background	4.0	12	1.0	85	Yes	1.0
	background-attachment	7.0
	background-color	4.0
	background-image	8.0
	background-position	8.0
	background-repeat	4.0
css- backgrounds-3	background (multiple)	9.0 [t 1]	12	1.9.2	312	3.5	2.5
	background-clip			2.0 [g 20]	Yes [w 16]	Experimental
	background-origin
	background-size				Yes [w 17]
Early ideas for css- backgrounds-4	background-position-x	8.0 [t 15]	12	No	Experimental	No	No
	background-position-y
Fonts
CSS2	font	4.0	12	1.0	85	Yes	Incorrect
	font-family	4.0		1.0	85	Yes	1.0
	font-size	3.0		1.0	85	Yes
	font-style	4.0		1.0	85	Yes
	font-variant	4.0		1.0	125	Yes
	font-weight	8.0		Partial	Partial	Yes	Incorrect
css-fonts-3	font-size-adjust	10.0 [t 16]	12	1.9	No [w 18]	No	No
	font-stretch	9.0 [t 1]		9.0 [g 21]	No [w 19]	No	No
	font-feature-settings	10.0 [t 17]		34.0 [2] [g 22]	No [w 20]	No	No
	font-kerning	No	No		No	No	No
	font-language-override	No			No	No	No
	font-synthesis	No			No	No	No
	font-variant-alternates	No			No	No	No
	font-variant-caps
	font-variant-east-asian
	font-variant-ligatures
	font-variant-numeric
	font-variant-position
	unicode-range	9.0 [t 18]	12	38.0 [g 23]	No	No	No
Text
CSS2	text-align	4.0	12	1.0	85	Yes	1.0
	text-decoration	Yes		1.0	85	Yes
	text-indent	3.0		1.0	85	Yes
	text-transform	4.0		1.0	85	Yes
	letter-spacing	4.0		1.0	85	Yes
	word-spacing	8.0		1.0	85	Yes
	white-space	8.0		1.9.1	522	Yes	2.1
css-text-3	word-break	Partial	Partial	15.0 [g 24]	No	No	No
	line-break	11.0	12	No	No	No	No
	hyphens	10.0 [t 19]	12	6.0 [g 25]	Experimental	No	No
	word-wrap	5.0	12	1.9.1	85	4.3	2.5
	overflow-wrap	No	No	No [g 26]	No	No	No
	text-align-last	Partial	Partial	12.0 [g 27]	No [w 21]	No	No
	text-justify	5.5	12	No [g 28]	No	No	No
	text-emphasis	No	No	No	No	No	No
	hanging-punctuation	No	No	No	No [w 22]	No	No
Early ideas for css- text-4	hyphenate-character	No	No	No	No	No	No
	hyphenate-limit-zone	10.0 [t 20]	12
	hyphenate-limit-chars	10.0 [t 21]	12
	hyphenate-limit-lines	10.0 [t 22]	12
	hyphenate-limit-last	No	No
	text-space-collapse
	text-spacing
	text-wrap
Text Decoration
css-text- decor-3	text-shadow	10.0 [t 23]	12	1.9.1	Yes	3.4	2.1
	text-decoration-style	No	No	36.0 [g 29] [g 30]	No [w 23]	No	No
	text-decoration-color	No	No			No	No
	text-decoration-line	No	No			No	No
	text-decoration-skip	No	No	No		No	No
	text-underline-position	11.0	12	No	No	No	No
	text-emphasis-style	No	No	No	No	No	No
	text-emphasis-color
	text-emphasis
	text-emphasis-position
		MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
Writing Modes
CSS2	direction	5.0	12	1.0	85	Yes	1.0
	unicode-bidi	5.0		1.0	525	Yes
css- writing- modes-3	writing-mode	7.0 [t 24]	12	No [g 31]	Nightly Build [w 24]	No	No
	text-combine-horizontal	11.0 [t 25]	12.0	No	No	No	No
	text-orientation	No	No	No	No	No	No
Tables
CSS2	border-collapse	8.0	12	1.0	125	Yes	1.0
	border-spacing	8.0		1.0	125	Yes
	caption-side	8.0		1.4	85	Yes
	empty-cells	8.0		1.0	125	Yes
	table-layout	5.0		1.0	85	Yes
User interface
CSS2	cursor	5.5	12	1.8	125	Yes	Partial
	outline	8.0		1.8	125	Yes	1.0
	outline-color	8.0		1.8	125	Yes
	outline-style	8.0		1.8	125	Yes
	outline-width	8.0		1.8	125	Yes
css-ui-3	outline-offset	No	No	1.8	125	3.5	2.1
	box-sizing	8.0	12	29.0 [g 32]	Yes [w 25]	3.3.2	1.0
	resize	No	No	2.0 [g 33]	525	No	No
	appearance	No	12	Experimental	Experimental	No	No
	icon	No	No	No	No	No	No
	nav-index	No		No	No	No	2.1
	nav-up	No		No	No	No
	nav-right	No		No	No	No
	nav-down	No		No	No	No
	nav-left	No		No	No	No
	text-overflow	Partial	Partial	7.0 [g 34]	Partial	3.5.6	Experimental (Nightly) [p 3]
Paged media
CSS2
	page-break-before	4.0	12	Partial	Partial	3.5	1.0
	page-break-after
	page-break-inside	8.0		19.0 [g 35]	312
	orphans			No [g 36]
widows
css-page-3	page	No	No	No	No	No	No
	size	No		No [g 37]	No [w 26]	No	1.0
	image-orientation	No		26.0 [g 38]	No	No	No
	object-fit	No		36.0 [g 39]	No	No	2.7 [p 4]
	object-position	No			No	No
Speech
css-speech-1	cue	No	No	No [g 40]	No	No	1.0
	cue-after
	cue-before
	pause
	pause-after
	pause-before
	speak				Nightly build [w 27]
	voice-family				No
	voice-balance						Experimental
	voice-duration
	voice-pitch
	voice-pitch-range
	voice-rate
	voice-stress
	voice-volume
	interpret-as
	phonemes
	rest						No
	rest-after
	rest-before
	mark
	mark-after
	mark-before
		MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
Media Queries
css3- mediaqueries	width	9.0 [t 26]	12	1.9.1	525	4.1	2.0
	height
	device-width
	device-height
	device-aspect-ratio
	color						2.5
	color-index
	monochrome
	resolution				No
	orientation					4.2.1	No
	aspect-ratio						2.1
	grid	11.0		Yes		4.1	2.5
	scan
Ruby characters
css-ruby-1	ruby-position	No	No	38.0 [g 41]	No	No	No
	ruby-align
	ruby-merge			No
Multi-column Layout
css- multicol-1	column-count	10.0 [t 27]	12	Experimental [g 42]	Experimental	No	2.8 [p 5]
	column-width
	column-gap
	column-rule
	columns			9.0 [g 43]
	break-before			No [g 44]	Experimental [w 28]
	break-after
	break-inside				No [w 29]
	column-fill			14.0 [g 45]	No
	column-span			No [g 46]	Experimental [w 30]
Grid layout
css- grid-1	grid	No	No	Experimental [g 47]	Experimental [w 31]	No	No
	grid-template
	grid-template-columns
	grid-template-rows
	grid-template-areas
	grid-auto-columns
	grid-auto-rows
	grid-auto-flow
	grid-auto-position
	grid-columns	10.0 [t 28]	12
	grid-columns-start	No	No
	grid-columns-end
	grid-row	10.0 [t 29]	12
	grid-row-start	No	No
	grid-row-end
	grid-area
Animation
css- animations-1
	animation	10.0 [t 30]	12	16.0 [g 48]	Experimental	No	2.12
	animation-delay
	animation-direction
	animation-duration
	animation-iteration-count
	animation-name
	animation-play-state
	animation-timing-function
	animation-fill-mode
Transforms
css- transforms- 1
	transform	10.0 [t 31]	12	16.0	Experimental	No	2.12
	transform-origin
	transform-style						No
	perspective
	perspective-origin
	backface-visibility
Transitions
css- transitions-1
	transition-property	10.0 [t 32]	12	16.0 [g 49]	Experimental	No	Experimental
	transition-duration
	transition-timing-function
	transition-delay
	transition
Flexible Box Layout
css- flexbox-1
	flex	11.0	12	22.0 [g 50]	9.0 [w 32]	No	2.12
	flex-basis						No
	flex-direction						2.12
	flex-flow			28.0			No
	flex-grow			22.0			2.12
	flex-shrink						No
	flex-wrap			28.0			No
	order			22.0			2.12
		MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
Regions
css- regions-1
	flow-into	10.0 [t 33]	12	No [g 51]	Nightly build	No	No
	flow-from
	region-fragment	No	No
	break-before	No	No
	break-after
	break-inside
Exclusions
css3- exclusions
	wrap-flow	10.0 [t 34]	12	No [g 52]	Nightly build	No	No
	wrap-through
Shapes
css- shapes-1
	shape-margin	No	No	No	Nightly build	No	No
	shape-outside				No
	shape-image-threshold
Masking
CSS2	clip	8.0	12	1.0	85	Yes	1.0
css- masking-1
	clip-path	No	No	1.9.1	No	No	No
	clip-rule			No
	mask	No	No	Partial	Partial	Partial	Partial
	mask-box-image	No	No	No	Experimental	No	No
	mask-box-image-outset				No
	mask-box-image-repeat
	mask-box-image-slice
	mask-box-image-source
	mask-box-image-width
	mask-clip	No	No	No	Experimental	No	No
	mask-image
	mask-origin
	mask-position
	mask-repeat
	mask-size
	mask-type			20.0	No
Compositing and Blending
compositing- 1
	mix-blend-mode	No	No	32.0	No	No	No
	isolation			36.0
	background-blend-mode			30.0
Filter Effects
filter- effects-1
	filter	No	13	35.0 [g 53]	18.0 [w 33]	No	No
	flood-color		No	No	No
	flood-opacity
	color-interpolation-filters
	lighting-color
Pointer events
SVG1.1 and earlier draft of css3-ui	pointer-events	11.0	12.0	1.9.2	530	No	2.0
pointer- events	touch-action	11.0	12.0	29.0 [g 54]	No	No	No
Line Grid
css-line- grid-1
	box-snap	No	No	No	No	No	No
	line-grid
	line-slack
	line-snap
		MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
Logical Properties
Early ideas for css- logical-1
	block-size	No	No	41.0 [g 55]	No	No	No
	inline-size
	min-block-size
	min-inline-size
	max-block-size
	max-inline-size
	margin-block-start
	margin-block-end
	margin-inline-start
	margin-inline-end
	offset-block-start
	offset-block-end
	offset-inline-start
	offset-inline-end
	padding-block-start
	padding-block-end
	padding-inline-start
	padding-inline-end
	border-block-start-width
	border-block-end-width
	border-inline-start-width
	border-inline-end-width
	border-block-start-style
	border-block-end-style
	border-inline-start-style
	border-inline-end-style
	border-block-start-color
	border-block-end-color
	border-inline-start-color
	border-inline-end-color
	border-block-start
	border-block-end
	border-inline-start
	border-inline-end
	background-image-transform			No
	border-image-transform
Will Change
css-will- change-1	will-change	No	No	36.0	No	No	No
CSSOM View
cssom- view	scroll-behavior (optional [3] )	No	No	36.0	No	No	No
Scroll Snap Points
Early ideas for css- snappoints	scroll-snap-type	10.0	12	39.0 [g 56]	No	No	No
	scroll-snap-points-x
	scroll-snap-points-y
	scroll-snap-destination
	scroll-snap-coordinate
		MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto

MSHTML notes

1. margin—inherit inherits the computation and recomputes it instead of inheriting the computed value. ^{[t 35]}
2. display— Prior to 7.0, only none, block, inline, table-header-group, and table-footer-group are fully supported. Prior to 8.0, table are not supported, while inline-block is only supported on elements that are naturally inline.
3. overflow— Prior to 7.0, overflow: visible; is incorrectly supported. In 8.0, scroll makes the element's height equal to its max-height even if the content isn't that tall. ^{[t 36]} This has been fixed in IE9.
4. visibility— Prior to 8.0, visibility: collapse; is not supported. In 8.0, inline elements with visibility: visible; inside block elements with visibility: hidden; are not visible. ^{[t 37]}
5. content— In 8.0, computed attr() values are not updated when the attribute changes. ^{[t 38]}
6. border-color— Prior to 7.0, transparent is not supported.
7. border-style— Prior to 8.0, hidden is not supported.
8. border-style— Prior to 7.0, dotted is rendered as dashed.
9. box-shadow— MSHTML 9.0 renders box-shadow blur value at about half the declared value. Prior to 9.0, MSHTML supports similar functionality since 5.5 using the proprietary Shadow ^{[t 39]} and DropShadow ^{[t 40]} filters.
10. position— Prior to 7.0, fixed positioning was not supported. 7.0 and later support it in standards-compliant mode only.
11. z-index— Prior to 8.0, z-index is only partially supported. ^{[t 41]} In 8.0, floating point values are accepted in addition to integers. ^{[t 42]}
12. list-style-type— Prior to 8.0, armenian, decimal-leading-zero, georgian, lower-greek, lower-latin, upper-latin are not supported.
13. opacity— Prior to 9.0, MSHTML supported a proprietary alternative. ^{[t 43]}
14. background-image— Prior to 8.0, background images are badly positioned in some cases. ^{[t 44] [t 45]}
15. background-attachment— Prior to 7.0, fixed was allowed on the body element only.
16. background-position— Prior to 8.0, fixed positioning is not supported.
17. font-weight— Prior to 8.0, incorrect rendering when value is 600. ^{[t 46]}
18. text-align— In 8.0, text-align isn't inherited by :before and :after pseudo-elements. ^{[t 47]}
19. white-space— Prior to 6.0, pre is not supported. Prior to 8.0, white-space is only partially supported; pre-line and pre-wrap are not supported. ^{[t 48]}
20. cursor— Does not fail on non-prefixed vendor extensions.
21. flex— Experimental in 10.0 ^{[t 49]}
22. break-after; break-before; break-inside— Though 10.0 does support break-after, break-before, and break-inside for columns, they do not appear to support the properties "region" and "avoid-region".

Gecko notes

1. display— Values except inline-block and inline-table supported prior to 1.9.
2. z-index— Negatives values are badly supported prior to 1.9.
3. content—none value is unsupported prior to 1.9. This property also fails on any normal (non-pseudo-) elements, which it must support according to the CSS3 "Generated and Replaced Content Module" spec.
4. background-position— Versions prior to 1.7 implement the CSS2 syntax, not the proposed CSS2.1 expanded syntax.
5. font-size-adjust— Prior to 1.9, supported on Windows only.
6. font-weight— Only Regular and Bold weights get used, even if Light or Heavy/Black faces are installed, unless using DirectWrite in Gecko 2.0 on Windows 7 or Windows Vista.
7. white-space—pre-line is not supported prior to 1.9.1. Prior to 1.9, pre-wrap was only supported experimentally as -moz-pre-wrap.
8. visibility—collapse is unsupported prior to 1.8.
9. border-radius— Prior to 1.9.1, border curves are circular, not elliptical as specified by the current CSS3 draft. Short-cut definitions for border-radius read "tl tr br bl" instead of the W3C's "tr br bl tl". When the border style is dotted or dashed, curves are rendered as solid instead. ^{[g 57]}
10. page-break-before; page-break-after— Only the always and auto values are supported.

WebKit notes

1. max-width; max-height; min-width; min-height— Are not supported on tables.(as commented on 2012-12-18, it is fixed) ^{[w 34]}
2. font— The system font keywords that allow designers to tailor presentation to the user's operating system environment are unsupported.
3. font-weight— Only Regular and Bold weights get used, even if Light or Heavy/Black faces are installed.
4. page-break-before; page-break-after— Only the always and auto values are supported.
5. white-space— Prior to 522, pre-line and pre-wrap are unsupported.
6. visibility—collapse is unsupported prior to 522. Its implementation has the same effect as hidden and is therefore not compliant. ^{[w 35]}
7. content— The none, open-quote, close-quote, no-open-quote, no-close-quote and normal values are unsupported. This property also fails on any normal (non-pseudo-) elements, which it must support according to the CSS3 "Generated and Replaced Content Module" spec.
8. font-size— The font-size property does not always accept the value 0, in "font-size: 0px" the text is still visible.

KHTML notes

1. overflow— Values scroll and auto are unsupported.
2. page-break-before; page-break-after— Before 3.5 only the always and auto values were supported.
3. visibility— All properties are supported, but the implementation of collapse has the same effect as hidden and is therefore not compliant.

Presto notes

1. counter-increment, counter-reset— Implemented the algorithm in REC CSS2.
2. background-position— Presto versions prior to Opera 8.0 implement the CSS2 syntax, not the proposed CSS2.1 expanded syntax.
3. font-weight— Incorrect rendering when value is 600. Renders the text in a compatibility mode for websites made for MSHTML.
4. visibility— Prior to 2.5, the value collapse was unsupported in table columns. On rows, it had the same effect as hidden and was therefore not compliant.
5. cursor—cursor is ignored with dynamic pseudo-classes and custom cursors are unsupported.
6. content— Prior to 2.7, the none value was unsupported. ^{[p 6]}
7. font—inherit should not be allowed together with a font-size value. This should not be parsed, but it's currently done in Opera.

Descriptors

		MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
@counter-style
css- counter- styles- 3	additive-symbols	No	No	No [g 58]	No	No	No
	fallback
	negative
	pad
	prefix
	range
	speak-as
	suffix
	symbols
	system
@font-face
css- fonts- 3	font-family	Yes	12	Yes	Yes	Yes	Yes
	font-feature-settings
	font-stretch				No	No	No
	font-style				Yes	Yes	Yes
	font-variant
	font-weight			Partial	Partial		Incorrect
	src			Yes	Yes		Yes
	unicode-range			36.0 [g 59]	No	No	No
@viewport
css- device- adapt-1	height	10.0 [t 50]	12	No	No	No	2.7
	max-height	No	No				No
	min-height
	width	10.0 [t 51]	12				2.7
	max-width	No	No				No
	min-width
	zoom						2.7
	max-zoom
	min-zoom
	user-zoom
	orientation						No

Values and units

			MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto
Numbers [spec 11]
CSS2	<number>	A floating-point number	3.0	12	1.0	85	Yes	1.0
	<length>	<number> followed by units
	<percentage>	<number> followed by %
	<integer>	An integer
css-values-3	<angle>	<number> angle-unit	9.0 [t 1]	12	Yes	Partial	Partial	Partial
	<time>	<number> time-unit			2.0 [g 49]	Yes	Yes	2.5
	<frequency>	<number> frequency-unit	No	No	No			No
	<fraction>	Remaining space				No	No
Strings
CSS2	<string>	String	3.0	12	1.0	85	Yes	1.0
	\code	Unicode escapes	6.0
Functions
CSS2	rect()	A rectangle	8.0	12	1.0	85	Yes	1.0
	url()	Uniform Resource Identifier	3.0	12	1.0	85	Yes	1.0
	counter()		8.0
	attr()	Attribute identifier
css-values-3	calc()		9.0 [t 1]	12	16.0 [g 60]	Yes [w 36]	No	No
	toggle()	Toggling between values	No	No	No [g 61]	No	No	No
css- grid-1  ?	repeat()	Repeat n times	No	No	32.0 [g 62]	No	No	No
Colors
CSS2	HTML4 color keywords	16 predefined web colors	3.0	12	1.0	85	Yes	1.0
	#rrggbb or #rgb	Hexadecimal notation
	rgb(r, g, b)	RGB notation	4.0
	system colors [spec 12]	28 predefined system colors	3.0
css-color-3	SVG color keywords		8.0	12	Yes	Yes	Yes	Yes
	currentColor	The value of the color property.	9.0 [t 1]		1.8	528	Yes	2.1
	rgba(r, g, b, a)	RGBA notation			1.9	525	4.0	2.2
	hsl(h, s, l)	HSL notation			1.5		3.5.5	2.1
	hsla(h, s, l, a)	HSLA notation			1.9		3.5.5	2.2
	transparent	Full transparency	9.0		1.9		4.0	Partial
Image values
CSS2	<url>	Image types	3.0	12	1.0	85	Yes	1.0
css- images-3	<sprite>		No	No	No	No	No	No
	<image-list>				No	No		No
	<linear-gradient>		10.0 [t 52]	12	16.0	Yes		Experimental
	<radial-gradient>
	linear-gradient()	Color gradients
	radial-gradient()
	repeating-linear-gradient()
	repeating-radial-gradient()
css- images-4	conic-gradient()		No	No	No	No	No	No
	repeating-conic-gradient()
	element()	Reproduce element	No	No	Experimental	No	No	No
	cross-fade()	Transitioning between images	No	No	No [g 63]	No	No	No
	image-set()	Resolution negotiation	No	No	No	No	No	No
Counter Styles [spec 13]
css- counter- styles-3	symbols()	Anonymous Counter Styles	No	No	No	No	No	No
Keywords
CSS2	auto	Automatically calculated	6.0	12	1.0	85	Yes	1.0
	inherit	Inherited from the parent	8.0
css-values-3	initial		No	13	19.0	125	No	No
Units
CSS2	px	Pixel	3.0	12	1.0	85	Yes	1.0
	pt	Point
	pc	Pica
	cm	Centimetre
	mm	Millimetre
	in	inch
	em	em
	ex	ex
	%	Percentage
css-values-3	deg	Degree	9.0 [t 1]	12	1.9.1	Yes	Yes	2.5
	grad	Grad
	rad	Radian
	turn	turn			13.0 [g 64]	No	No	No
	ms	Millisecond			2.0 [g 65]	Yes	Yes	2.5
	s	Second
	Hz	Hertz	No	No	No			No
	kHz	Kilohertz
	dpi	Dots per inch		12	1.9.1	No	4.1	2.5
	dpcm	Dots per centimetre
	dppx	Dots per pixel-unit			16.0	No	?	No
earlier draft of css-line- grid-1	gd	Cells in the layout-grid		No	No	No	No	No
unit being considered for css- template- 3	fr	Remaining space in a series of length values		12	No	No	No	No
css-values-3	rem	the font size of the root element	9.0 [t 1]		1.9.2	Yes	No	2.10.229 [p 7]
	vw	the viewport's width			19.0 [g 3]	28.0 [w 37]	No	No
	vh	the viewport's height
	vmin	equal to the smaller of ‘vw’ or ‘vh’.	No
	vmax	equal to the larger of ‘vw’ or ‘vh’.
	ch	the width of the "0" (ZERO, U+0030) glyph found in the font for the font size used to render.	No		1.9.1	No	No	No
Filter Effects
filter- effects
	grayscale()		No	13	35.0 [g 66]	18.0 [w 38]	No	No
	sepia()
	saturate()
	hue-rotate()
	invert()
	opacity()
	brightness()
	contrast()
	blur()
	drop-shadow()
	Variables
css- variables- 1
	--*	define variable	No	No	31.0 [g 67]	Experimental [ citation needed ]	No	No
	var(--*)	use variable
			MSHTML	EdgeHTML	Gecko	WebKit	KHTML	Presto

General notes

1. transparent—

   CSS1 introduced the ‘transparent’ value for the background-color property. CSS2 allowed border-color to also accept the ‘transparent’ value. The Open eBook(tm) Publication Structure 1.0.1 [OEB101] extended the ‘color’ property to also accept the ‘transparent’ keyword. CSS3 extends the color value to include the ‘transparent’ keyword to allow its use with all properties that accept a <color> value. This simplifies the definition of those properties in CSS3.

2. <angle>— The turn unit is unsupported.

MSHTML notes

1. rect()— Prior to 8.0, rect() was not supported with the correct syntax using commas.
2. auto— In quirks mode (IE5 emulation mode), auto does not work for margins, except table elements.
3. transparent— In 7.0 and 8.0, using transparent in the color property will render the text as black.
4. transparent— Prior to 7.0, transparent is not supported on borders (shows as solid black) and is ignored on PNG images.

Gecko notes

1. <ch>— Prior to version 1.9.1, used the width of the "M" glyph instead of the width of the "0" glyph. ^{[g 68]}

Presto notes

1. <number>— Prior to 2.1, there existed a quantization error for values greater than 20.47 (not limited to em, try any non-pixel units). ^{[p 8]}
2. transparent— Keyword is ignored when used with the outline-color property. Prior to version 2.2, it was also ignored when used with the color and text-shadow properties.

See also

• Comparison of browser engines

References

1. Mackie, Kurt (10 December 2018). "Microsoft Edge Browser To Get New Rendering Engine but EdgeHTML Continues". Redmond Mag. Retrieved 21 December 2019.
2. MDN: Web technology for developers: font kerning
3. The cssom-view specification of this property says that “[u]ser agents may ignore this property.”

Specifications

1. Cascading Style Sheets, level 1, W3C
2. Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification, W3C
3. CSS Paged Media Module Level 3 - Margin Boxes, W3C
4. Selectors Level 3, W3C, 30 January 2018
5. Markers: The '::marker' pseudo-element, W3C
6. User interface element fragments: pseudo-elements3, W3C
7. CSS basic box model, W3C
8. CSS Inline Layout Module Level 3, W3C
9. CSS Generated Content Module Level 3, W3C
10. CSS Lists Module Level 3, W3C
11. Values and Units Module Level 3, W3C
12. System Colors, W3C
13. CSS Counter Styles Level 3, W3C

MSHTML

1. Internet Explorer Platform Preview Guide for Developers, Microsoft
2. @keyframes rule (Internet Explorer), Microsoft
3. "@-ms-viewport rule", Internet Explorer Dev Center, Microsoft
4. HTML5, Native: Third IE9 Platform Preview Available for Developers, Microsoft
5. "valid pseudo-class (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
6. "invalid pseudo-class (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
7. "required pseudo-class (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
8. "optional pseudo-class (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
9. Hopkins, James, Attribute selector (which matches the attribute, 'colspan' for TD and TH elements) matches every TD and TH element
10. Hammond, David, Comment on "IE 8 CSS 2.1 support results"
11. first-letter Ignore Bug, hasLayout.net, archived from the original on 2010-03-02, retrieved 2010-01-29
12. Hopkins, James, Declaration which includes !important keyword is ignored when used within a :first-letter or :first-line rule
13. Box-shadow, one of CSS3′s best new features - Browser's support (including IE9), WEBFLUX
14. content property doesn't return the value of an attribute when attribute is dynamically, archived from the original on 2009-10-17, retrieved 2011-03-12
15. "background-position-y property (Internet Explorer)". msdn.microsoft.com. MSDN. Retrieved 16 Feb 2015.
16. "font-size-adjust property (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
17. "font-feature-settings property (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
18. "@font-face rule (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
19. "-ms-hyphens property (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
20. "-ms-hyphenate-limit-zone property (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
21. "-ms-hyphenate-limit-chars property (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
22. "-ms-hyphenate-limit-lines property (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
23. "text-shadow property (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
24. CSS 3 Text: A Tale of writing-mode Woe
25. "-ms-text-combine-horizontal property". Microsoft. Retrieved 8 November 2013.
26. "@media rule (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
27. "Multi-column Layout (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
28. "-ms-grid-columns property". Microsoft. Retrieved 8 November 2013.
29. "-ms-grid-row property". Microsoft. Retrieved 8 November 2013.
30. "Animations (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
31. "Transforms (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
32. "Transitions (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
33. "Regions (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
34. "Exclusions (Internet Explorer)". Microsoft. Retrieved 17 November 2012.
35. Talbot, Inherited margin with inherit keyword: the computed value's parent should be inherited
36. Groot, Sven, Overflow: scroll causes element to always have its max-height
37. Hopkins, James, visibility:visible applied to inline element doesn't override inherited visibility:hidden value applied to its block-level parent
38. Content: attr(x) isn't updated when the attribute's value change
39. Shadow Filter, Microsoft
40. DropShadow Filter, Microsoft
41. Positioning
42. Hopkins, James, Illegal parsing of a z-index decimal value, instead of an integer
43. Alpha Filter, Microsoft
44. IE7-/Escaping Background Image Bug - Demo 1, archived from the original on 2010-01-03, retrieved 2010-01-29
45. IE7-/Escaping Background Image Bug - Demo 2, archived from the original on 2010-04-22, retrieved 2010-01-29
46. Koch, Peter-Paul, IE Windows and Opera - font-weight: 600 vs. bold, QuirksMode
47. Hopkins, James, 'text-align' value isn't inherited by ':before' and ':after' pseudo elements
48. Font and Text, Microsoft
49. Flexible Box ("Flexbox") Layout, Microsoft
50. CSS Device Adaptation with @viewport, Treehouse Blog, 6 August 2013
51. CSS Device Adaptation with @viewport, Treehouse Blog, 6 August 2013
52. "Gradients (Internet Explorer)". Microsoft. Retrieved 17 November 2012.

Gecko

1. @supports - CSS, MDN
2. Bug 966166 - Implement @counter-style rule, Mozilla
3. "What's New", Firefox 19 Release Notes, Mozilla
4. Bug 418039 - CSS parent (has-child) and ancestor (has-descendant) selectors (:subject), Mozilla
5. Bug 813187 - Support CSS 2.1 @page Page Selectors, Mozilla
6. Bug 506554 - Implement the CSS3 pseudo-classes :required and :optional, Mozilla
7. Bug 312971 - Support :read-only and :read-write pseudoclasses, Mozilla
8. Bug 561154 - fix specificity of :-moz-any(), Mozilla
9. Bug 562169 - Implement the :dir(rtl/ltr) selector to select on HTML directionality, Mozilla
10. Bug 843579 - Remove prefix from :any-link pseudo-class, Mozilla
11. Bug 648722 - Add support for :scope as :-moz-scope, Mozilla
12. Bug 237119 - property 'display' is ignored for generated content, Mozilla
13. Bug 842329 - [css3-cascade] implement the 'all' shorthand, Mozilla
14. Bug 451134 - change -moz-border-radius* properties to css3-background names, Mozilla
15. Bug 378217 - implement css3 'border-image' property, Mozilla
16. Bug 497995 - Implement border-image revisions in latest css3-background, Mozilla
17. Bug 590039 - fix blur radius computation and rename -moz-box-shadow to box-shadow, Mozilla
18. Bug 470547 - Spread (4th length) for text-shadow not supported, Mozilla
19. Bug 613659 - implement box-decoration-break: Left/right part of a box-shadow should only be drawn on the first/last continuation of an inline box, Mozilla
20. Bug 549809 - Rename background-origin and background-clip properties and values to match css3-background, Mozilla
21. Bug 3512 - (font-stretch) Implement font-stretch property, Mozilla
22. Bug 549861 - (font-variant) implement parsing of font feature properties, Mozilla
23. Bug 475891 - (unicode-range) implement unicode-range support in user font set, Mozilla
24. Bug 249159 - implement 'word-break' properties of CSS3, Mozilla
25. hyphens - MDN Docs, Mozilla (Only English)
26. Bug 587438 - word-wrap, Mozilla
27. Bug 536557 - Implement CSS3 text-align-last, Mozilla
28. Bug 276079 - Implement text-justify property(but 'auto', 'inter-word', 'inter-ideograph' and 'distribute' only), Mozilla
29. Bug 59109 - implement CSS3 text module's text-decoration-style and text-decoration-color, Mozilla
30. Firefox 6 for developers, Mozilla, archived from the original on 2012-05-12, retrieved 2011-04-24
31. Bug 145503 - (writing-mode) CSS3 writing-mode (vertical text), Mozilla
32. Implement 'box-sizing', Mozilla
33. Bug 553576 - Implement css resize property behaviour, Mozilla
34. Bug 312156 - implement text-overflow: ellipsis from CSS3 text, Mozilla
35. Bug 132035 - Implement missing page-break-* CSS2.1 features, Mozilla
36. Bug 137367 - Implement orphans and widows, Mozilla
37. Bug 851937 - Support for @page size, Mozilla
38. Bug 825771 - [css3-images] implement 'image-orientation' property, Mozilla
39. Bug 624647 - [css3-images] Implement object-fit and object-position CSS properties, Mozilla
40. Bug 47159 - Support css3-speech (previously Aural Style Sheet) properties in getComputedStyle, Mozilla
41. Bug 256274 - Implement CSS ruby module, Mozilla
42. Bug 684062 - Compare spec and implement CSS multi-column support, Mozilla
43. Bug 446569 - Implement CSS3 columns shorthand, Mozilla
44. Bug 549114 - Support Column Breaks, Mozilla
45. Bug 695222 - Implement column-fill, Mozilla
46. Bug 616436 - column-span not implemented (css3 multicolumn), Mozilla
47. Bug 616605 - CSS Grid Layout, Mozilla
48. Bug 435442 - Implement Webkit's CSS Animation proposal, Mozilla
49. Bug 435441 - get CSS transitions complete enough to ship, Mozilla
50. Bug 783409 - Turn on CSS flexbox in builds by default (by enabling pref, build flag, etc), Mozilla
51. Bug 674802 - implement CSS3 Regions, Mozilla
52. Bug 674804 - implement CSS3 Exclusions, Mozilla
53. Bug 1057180 - Turn on CSS Filters by default (by enabling about:config pref), Mozilla
54. Bug 795567 - Implement touch-action CSS property for Pointer Events, Mozilla
55. Bug 1138384 - (enable-writing-mode-release) enable CSS writing-mode support in release channels, Mozilla
56. Bug 945584 - Implement CSS scroll snapping, Mozilla
57. Bug 382721 - Dotted/dashed -moz-border-radiused corners are rendered as solid, Mozilla
58. Bug 843718 - (css-counter-styles-3) Implement CSS Counter Styles Level 3, Mozilla
59. Bug 475891 - (unicode-range) implement unicode-range support in user font set, Mozilla
60. Bug 363249 - implement css3-values calc(), Mozilla
61. Bug 363250 - implement toggle() expression, Mozilla
62. Bug 978478 - Support repeat() in CSS Grid templates, Mozilla
63. Bug 546052 - Support CSS transitions with background-image images (cross-fading), Mozilla
64. Bug 716628 - Support "turn" unit from CSS3 Values and Units, Mozilla
65. Bug 435441 - Implement Webkit's CSS Transitions proposal, Mozilla
66. Bug 1057180 - Turn on CSS Filters by default (by enabling about:config pref), Mozilla
67. Bug 773296 - CSS Variables, Mozilla
68. Bug 282126 - What to do about the 'ch' length unit? (Mozilla vendor specific), Mozilla

Webkit

1. @supports - CSS, MDN
2. Bug 747754 - [CSS-WD] implement CSS Device Adaptation, Mozilla
3. Bug 35329 - Enhance CSS parser for Paged Media (Iteration 1), WebKit
4. Bug 85062 - Support CSS 3 Paged Media Margin Boxes, WebKit
5. Bug 38731 - Make CSS Parser properly handle only-for-pages pseudo-classes, WebKit
6. Bug 27458 - Support :default HTML5 CSS selector, Webkit
7. Bug 27357 - Support :valid/:invalid CSS selectors, Webkit
8. Bug 29071 - Support for :in-range and :out-of-range CSS selectors, Webkit
9. Bug 25551 - Support for HTML5 Forms "required" attribute, Webkit
10. Bug 3409 - CSS1: Safari ignores "text-transform" attribute in "first-line" CSS rules, Webkit
11. Bug 23209 - [RFE] CSS Generated Content does not transition, Webkit
12. Bug 27578 - Drop the prefix from the border-radius properties, Webkit
13. Bug 51448 - Support unprefixed box-shadow property, WebKit
14. Bug 27576 - [CSS3 Backgrounds and Borders] Implement box-decoration-break, WebKit
15. Bug 3234 - CSS2: Implement better quote support (for the q tag), Webkit
16. Bug 27562 - Drop the prefixes from background-clip and background-origin, WebKit
17. [CSS3 Backgrounds and Borders] Drop the prefix from background-size, WebKit
18. Bug 15257 - Support CSS 3 font-size-adjust, Webkit
19. Bug 12530 - CSS3: Support the font-stretch property, Webkit
20. Bug 63796 - Master: Support CSS3 font feature properties, Webkit
21. Bug 76173 - CSS3: text-align-last on webkit, Webkit
22. Bug 18109 - Implement hanging punctuation, Webkit
23. Bug 58491 - [css3-text] Support text-decoration-* properties from CSS3 Text, Webkit
24. Bug 46123 - Implement writing-mode support for all of layout (master bug), WebKit
25. Bug 36713 - Support box-sizing without the vendor prefix, WebKit
26. Bug 10894 - CSS "size" property is not supported, Webkit
27. Bug 46827 - AX: implement CSS3 Speech "speak", WebKit
28. Bug 15552 - Support CSS3 column-break-before and column-break-after, WebKit
29. Bug 39498 - [CSS3 Multi-column] Floating elements are rendered below the columns, WebKit
30. Bug 15550 - WebKit does not support CSS3 column-span, Webkit
31. Bug 60731 - Implement CSS3 Grid Layout (master bug), Webkit
32. flex - CSS, MDN
33. filter - CSS, MDN
34. Bug 25016 - max-width and max-height are not overriding the width and height properties when 'display' set to 'table', Webkit
35. Bug 8735 - CSS 2.1 visibility: collapse rendered as visibility: hidden, Webkit
36. Bug 16662 - CSS3: Implement calc(), Webkit
37. Can I use Viewport units, Can I Use
38. filter - CSS, MDN

Presto

1. An introduction to meta viewport and @viewport, dev.Opera
2. Storey, David (2010-11-23). "First browser to 11 (unless Chrome gets there first)". Opera. Archived from the original on 2010-12-08. Retrieved 2010-11-23.
3. Haavard (2010-08-09), New 10.70 snapshot with more Presto updates, Opera, archived from the original on 2010-08-19
4. Haavard (2010-08-03), Presto update for Opera 10.70, Opera, archived from the original on 2010-08-06
5. "CSS Multi-column Layout Module support in Opera Presto 2.8". Opera. 2011-03-06. Retrieved 2011-03-06.
6. Koch, Peter-Paul, before/:after and content, Quirksmode
7. Lawson, Bruce (2011-12-06). "Hello Opera 11.60!". Opera. Archived from the original on 2012-01-08. Retrieved 2012-05-05.
8. Quantization error for em values in Opera 7–9.2, archived from the original on 2008-03-21