Compatibility Standard

Compatibility Standard
Compatibility
Living Standard — Last Updated
15 March 2026
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Abstract
This standard describes a collection of web platform features that web browsers need to support for compatibility with the de facto web.
1.
Introduction
This section is non-normative.
There exists an increasingly large corpus of web content that depends on web browsers supporting a
number of specific vendor CSS properties and DOM APIs for functionality or layout.
This holds especially true for mobile-optimized web content, which is highly dependent on
-webkit-
-prefixed properties.
This specification aims to describe the minimal set of
-webkit-
-prefixed CSS properties
and DOM APIs that user agents are required to support for web compatibility, which aren’t
specified elsewhere.
The HTTP
User-Agent
header field as found in major browsers today is also described.
2.
Conformance
All diagrams, examples, and notes in this specification are
non-normative, as are all sections explicitly marked non-normative.
Everything else in this specification is normative.
The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC 2119.
For readability, these words do not appear in all uppercase letters in this
specification.
[RFC2119]
Requirements phrased in the imperative as part of algorithms
(such as "strip any leading space characters" or "return false and
terminate these steps") are to be interpreted with the meaning of the
keyword ("must", "should", "may", etc.) used in introducing the
algorithm.
Conformance requirements phrased as algorithms or specific steps
may be implemented in any manner, so long as the end result is
equivalent. (In particular, the algorithms defined in this
specification are intended to be easy to follow, and not intended to
be performant.)
3.
CSS Compatibility
3.1.
CSS At-rules
The following
-webkit-
vendor prefixed
at-rules
must be supported as aliases
of the corresponding unprefixed
at-rules
-webkit-
prefixed at-rule alias
unprefixed at-rule
@-webkit-keyframes
@keyframes
3.2.
CSS Media Queries
3.2.1.
-webkit-device-pixel-ratio
Name:
-webkit-device-pixel-ratio
For:
@media
Value:

Type:
range
-webkit-device-pixel-ratio
must be treated as an alias of the
resolution
range type
media feature
, with its value interpreted as a
dppx
unit.
The
min-
or
max-
prefixes on range features
must not apply to
-webkit-device-pixel-ratio
, instead the following aliases must be used:
legacy
-webkit-
prefixed range
media feature
alias
standard prefixed range
media feature
-webkit-min-device-pixel-ratio
min-resolution
-webkit-max-device-pixel-ratio
max-resolution
3.2.2.
-webkit-transform-3d
Name:
-webkit-transform-3d
For:
@media
Value:

Type:
discrete
The
-webkit-transform-3d
media feature
is used to query whether the
user agent supports CSS 3D transforms.
[css-transforms-1]
If the user agent supports 3D transforms, the value will be 1. Otherwise the value is 0.
3.3.
CSS Gradient Functions
3.3.1.
-webkit-linear-gradient()
The
-webkit-linear-gradient()
gradient function
must be treated
as an alias of
linear-gradient
as defined in
[css3-images-20110217]
3.3.2.
-webkit-radial-gradient()
The
-webkit-radial-gradient()
gradient function
must be treated
as an alias of
radial-gradient
as defined in
[css3-images-20110217]
3.3.3.
-webkit-repeating-linear-gradient()
The
-webkit-repeating-linear-gradient()
gradient function
must be
treated as an alias of
repeating-linear-gradient
as defined in
[css3-images-20110217]
3.3.4.
-webkit-repeating-radial-gradient()
The
-webkit-repeating-radial-gradient()
gradient function
must be
treated as an alias of
repeating-radial-gradient
as defined in
[css3-images-20110217]
3.4.
CSS Properties
3.4.1.
Legacy name aliases
The following
-webkit-
vendor prefixed
properties must be supported as
legacy name aliases
of the corresponding unprefixed property:
-webkit-
prefixed property alias
unprefixed property
-webkit-align-items
align-items
-webkit-align-content
align-content
-webkit-align-self
align-self
-webkit-animation-name
animation-name
-webkit-animation-duration
animation-duration
-webkit-animation-timing-function
animation-timing-function
-webkit-animation-iteration-count
animation-iteration-count
-webkit-animation-direction
animation-direction
-webkit-animation-play-state
animation-play-state
-webkit-animation-delay
animation-delay
-webkit-animation-fill-mode
animation-fill-mode
-webkit-animation
animation
-webkit-backface-visibility
backface-visibility
-webkit-background-clip
background-clip
-webkit-background-origin
background-origin
-webkit-background-size
Not really a
legacy name alias
. See
issue #28
background-size
-webkit-border-bottom-left-radius
border-bottom-left-radius
-webkit-border-bottom-right-radius
border-bottom-right-radius
-webkit-border-top-left-radius
border-top-left-radius
-webkit-border-top-right-radius
border-top-right-radius
-webkit-border-radius
border-radius
-webkit-box-shadow
box-shadow
-webkit-box-sizing
box-sizing
-webkit-flex
flex
-webkit-flex-basis
flex-basis
-webkit-flex-direction
flex-direction
-webkit-flex-flow
flex-flow
-webkit-flex-grow
flex-grow
-webkit-flex-shrink
flex-shrink
-webkit-flex-wrap
flex-wrap
-webkit-filter
filter
-webkit-justify-content
justify-content
-webkit-mask
mask
-webkit-mask-box-image
mask-border
-webkit-mask-box-image-outset
mask-border-outset
-webkit-mask-box-image-repeat
mask-border-repeat
-webkit-mask-box-image-slice
mask-border-slice
-webkit-mask-box-image-source
mask-border-source
-webkit-mask-box-image-width
mask-border-width
-webkit-mask-clip
mask-clip
-webkit-mask-composite
mask-composite
-webkit-mask-image
mask-image
-webkit-mask-origin
mask-origin
-webkit-mask-position
mask-position
-webkit-mask-repeat
mask-repeat
-webkit-mask-size
mask-size
-webkit-order
order
-webkit-perspective
perspective
-webkit-perspective-origin
perspective-origin
-webkit-transform-origin
transform-origin
-webkit-transform-style
transform-style
-webkit-transform
transform
-webkit-transition-delay
transition-delay
-webkit-transition-duration
transition-duration
-webkit-transition-property
transition-property
-webkit-transition-timing-function
transition-timing-function
-webkit-transition
transition
3.4.2.
Prefixed legacy name aliases
The following
-webkit-
vendor prefixed
properties must be supported as
legacy name aliases
of the corresponding unprefixed properties. If the
user agent does not ship the unprefixed equivalent, the
-webkit-
prefixed property must
be treated as an alias of the user agent’s own vendor prefixed property.
-webkit-
prefixed property alias
(vendor prefixed) property
-webkit-text-size-adjust
(-prefix-)
text-size-adjust
For example,
-webkit-text-size-adjust
is
treated as an alias
of
-moz-text-size-adjust
in Firefox.
Note:
As soon as each property is unprefixable it can be defined as a
legacy name alias
3.4.3.
Non-aliased vendor prefixed properties
Note:
This section used to specify the
-webkit-appearance
property.
This is now defined in
CSS Basic User Interface Module
3.4.4.
Property mappings
The following
-webkit-
vendor prefixed
properties must be supported as mappings
to the corresponding unprefixed property:
-webkit-
prefixed property
unprefixed property
-webkit-box-align
align-items
-webkit-box-flex
flex-grow
-webkit-box-ordinal-group
order
-webkit-box-orient
flex-direction
-webkit-box-pack
justify-content
These definitions of
-webkit-box-*
are known to not be web compatible.
[Issue #87]
3.4.5.
Keyword mappings
The following
-webkit-
vendor prefixed
keywords must be supported as mappings to
the corresponding unprefixed keyword:
-webkit-
prefixed keyword
unprefixed property keyword
-webkit-box
flex
-webkit-flex
flex
-webkit-inline-box
inline-flex
-webkit-inline-flex
inline-flex
This definition of
-webkit-box
is known to not be web compatible.
[Issue #87]
3.4.6.
Text Fill and Stroking
3.4.6.1.
Foreground Text Color: the
-webkit-text-fill-color
property
Name:
-webkit-text-fill-color
Value:

Initial:
currentcolor
Applies to:
all elements
Inherited:
yes
Percentages:
N/A
Computed value:
an RGBA color
Canonical order:
per grammar
Animation type:
by computed value type
Media:
visual
The
-webkit-text-fill-color
property defines the foreground
fill
color of an element’s text
content.
Here’s an example showing
-webkit-text-fill-color
will always determine the
foreground fill color of an element’s text.
.one
color
blue
/* the following can be omitted because it's the initial value:
-webkit-text-fill-color: currentcolor; */
.two
color
red
-webkit-text-fill-color
blue
Elements with the
one
or
two
classes will have blue text.
3.4.6.2.
Text Stroke Color: the
-webkit-text-stroke-color
property
Name:
-webkit-text-stroke-color
Value:

Initial:
currentcolor
Applies to:
all elements
Inherited:
yes
Percentages:
N/A
Computed value:
an RGBA color
Canonical order:
per grammar
Animation type:
by computed value type
Media:
visual
The
-webkit-text-stroke-color
property specifies a
stroke
color for an element’s text.
3.4.6.3.
Text Stroke Thickness: the
-webkit-text-stroke-width
property
Name:
-webkit-text-stroke-width
Value:

Initial:
Applies to:
all elements
Inherited:
yes
Percentages:
N/A
Computed value:
absolute length
Canonical order:
per grammar
Animation type:
discrete
Media:
visual
The
-webkit-text-stroke-width
property specifies the width of the
stroke
drawn at the edge of
each glyph of an element’s text. A zero value results in no
stroke
being painted. A negative
value is
invalid
3.4.6.4.
Text Stroke Shorthand: the
-webkit-text-stroke
property
Name:
-webkit-text-stroke
Value:

||

Initial:
See individual properties
Applies to:
See individual properties
Inherited:
yes
Percentages:
N/A
Computed value:
See individual properties
Canonical order:
per grammar
Animation type:
See individual properties
Media:
visual
The
-webkit-text-stroke
property is a shorthand property
for the
-webkit-text-stroke-width
and
-webkit-text-stroke-color
properties,
for setting the
stroke
width and
stroke
color of an element’s text.
Here are two examples showing how to use the longhand and shorthand
-webkit-text-stroke
properties to achieve white text with a black stroked text
effect.
.stroked-text-longhand
color
#fff
-webkit-text-stroke-color
#000
-webkit-text-stroke-width
px
.stroked-text-shorthand
-webkit-text-fill-color
#fff
-webkit-text-stroke
thin #000
The element

Serious typography

would be
rendered as follows:
3.5.
CSS Property values
3.5.1.
Additional
touch-action
values
This section augments the
definition of
touch-action
from
[pointerevents2]
to
add
the
pinch-zoom
value.
Name:
touch-action
Value:
auto
none
[ [ pan-x
pan-left
pan-right ]
||
[ pan-y
pan-up
pan-down ]
||
pinch-zoom ]
manipulation
Initial:
auto
Applies to:
all elements except: non-replaced inline elements, table rows, row groups, table columns, and column groups.
Inherited:
no
Percentages:
N/A
Computed value:
Same as specified value
Canonical order:
per grammar
Animation type:
not animatable
Media:
visual
When specified, the
pinch-zoom
token enables multi-finger panning and zooming of the
page. For zooming to occur, all fingers must start on an element that has the pinch-zoom behavior
enabled (via one of the
pinch-zoom
manipulation
, or
auto
values on itself or an ancestor).
Scenarios like image carousels which wish to disable only horizontal panning can
use "
touch-action: pan-y pinch-zoom
to avoid disabling zooming unnecessarily.
manipulation
is an alias for "
pan-x pan-y pinch-zoom
".
4.
DOM Compatibility
4.1.
The WebKitCSSMatrix interface
Note:
WebKitCSSMatrix
is now defined by the DOM Geometry specification.
[geometry-1]
4.2.
window.orientation
API
partial
interface
Window
readonly
attribute
short
orientation
attribute
EventHandler
onorientationchange
};
partial
interface
HTMLBodyElement
attribute
EventHandler
onorientationchange
};
When getting the
orientation
attribute, the user agent must run
the following steps:
Let
document
be
this
’s
relevant global object
’s
associated Document
Return
document
’s current
window.orientation
angle
Whenever the viewport is drawn at a different angle compared to the device’s natural orientation,
the user agent must run the following steps:
Fire an event
named
orientationchange
at the
Window
object of the
active document
User agents implementing the
window.orientation
attribute and its associated
orientationchange
event must not expose them on non-Mobile
platforms.
iOS Safari also fires an
orientationchange
event on the
body
element, but other implementations do not, suggesting it’s not necessary for
compatibility with the web.
4.2.1.
window.orientation
angle
The possible integer values for the
window.orientation
angle are:
-90
90
180
. User agents must
support the
-90
and
90
values and may optionally support
180
represents the natural orientation.
-90
represents a
rotation 90 degrees clockwise from the natural orientation.
90
represents a rotation
90 degrees counterclockwise from the natural orientation.
180
represents a rotation
180 degrees from the natural orientation.
In order to determine the current
window.orientation
angle, the user agent must run the following steps:
Let
orientationAngle
be the
current orientation angle
If
orientationAngle
is less than 180, return
orientationAngle
If
orientationAngle
is 180, and the
user agent
supports that value, return
orientationAngle
, else return 0.
If
orientationAngle
is greater than 180, return
orientationAngle
- 360.
4.2.2.
Event Handlers on
Window
objects and
body
elements
The following are the event handlers and their corresponding event handler event types that must be
supported on all
Window
objects and
body
elements as attributes:
event handler
event handler event type
onorientationchange
orientationchange
5.
The User-Agent String
This section is non-normative.
The
User-Agent
header field syntax is formally defined by
[HTTP-SEMANTICS]
and
provides SHOULD-level guidance on its value. This section describes the
User-Agent
patterns found in the so-called major web browsers, but much of it will
apply to other browsers with a shared heritage (i.e., forks and embedders) as well as any
user agent
in the more general sense that send a
User-Agent
header
5.1.
User-Agent Tokens
A User-Agent
token
is a string that represents an abstraction over a semantic unit in the
User-Agent
string. This document formalizes a
token
as a
string
that
begins with an opening bracket "<" and ends with a closing ">" bracket, e.g.,

. A
token
may also contain other
tokens
A User-Agent
constant
is a
string
whose value does not change.
When a
token
’s value is made up from one or more
tokens
, and optionally
constants
, it is said to
decompose
to those
tokens
and
constants
5.1.1.
User-Agent Token Reference
This is a non-exhaustive list of common User-Agent
tokens
Tokens
Description
deviceCompat
Represents the form-factor of the device. Primarily this is "
Mobile
", or
just the empty string, for Desktop or non-mobile devices. Some browsers have also sent token
values such as "
Tablet
", "
TV
", "
Mobile VR
", etc., or
included build information as well.
majorVersion
Represents the browser’s major version number.
minorVersion
Represents the browser’s non-major version numbers.
oscpu
Represents the device operating system and (optionally) CPU architecture.
platform
Represents the underlying device platform.
5.2.
Meta Structure
The User-Agent strings that follow share the common meta structure:
Mozilla/5.0
Where
is one or more
tokens
representing device information and
is
one or more
tokens
representing browser information.
5.3.
Chrome
5.3.1.
Chrome User-Agent pattern
Mozilla/5.0 (<
unifiedPlatform
>)
AppleWebKit/537.36 (KHTML, like Gecko) Chrome/<
majorVersion
>.0.0.0
deviceCompat
>Safari/537.36
Desktop
: "
Mozilla/5.0 (
Macintosh;
Intel Mac OS X 10_15_7
) AppleWebKit/537.36 (KHTML, like Gecko)
Chrome/
110
.0.0.0 Safari/537.36
Mobile
: "
Mozilla/5.0 (
Linux; Android 10; K
) AppleWebKit/537.36
(KHTML, like Gecko) Chrome/
110
.0.0.0
Mobile
Safari/537.36
5.3.2.
Chrome-specific tokens
Tokens
Description
unifiedPlatform
Per-platform
constant
that is one of the following values:
Linux; Android 10; K
Windows NT 10.0; Win64; x64
Macintosh; Intel Mac OS X 10_15_7
X11; Linux x86_64
X11; CrOS x86_64 14541.0.0
Fuchsia
5.4.
Firefox
5.4.1.
Firefox User-Agent pattern
Mozilla/5.0 (<
firefoxPlatform
>; rv: <
firefoxVersion
>) Gecko/<
geckoVersion
Firefox/<
firefoxVersion
Desktop
: "
Mozilla/5.0 (
Windows NT 10.0
Win64; x64;
rv:
100
.0) Gecko/20100101 Firefox/
100
.0
Mobile
: "
Mozilla/5.0 (
Android 10
Mobile;
rv:
100
.0) Gecko/
100
.0 Firefox/
100
.0
5.4.2.
Firefox-specific tokens
firefoxVersion
decomposes
to the following:
majorVersion
>.0
In Firefox on desktop platforms (Windows, macOS, Linux, etc.),
geckoVersion
is the frozen build
date "
20100101
". In Firefox for Android,
geckoVersion
is the
same value as
firefoxVersion
firefoxPlatform
decomposes
to the following:
On desktop platforms, "
platform
>; <
oscpu
".
On Firefox for Android, "
platform
>; <
deviceCompat
".
Tokens
Description
deviceCompat
The string "
Mobile
", without any leading or trailing spaces.
5.5.
Safari
5.5.1.
Safari User-Agent pattern
Mozilla/5.0 (<
safariPlatform
>) AppleWebKit/605.1.15 (KHTML, like Gecko)
Version/<
safariVersion
> <
deviceCompat
> Safari/<
webkitVersion
Desktop
: "
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15
(KHTML, like Gecko) Version/
15.6
Safari/
605.1.15
Mobile
: "
Mozilla/5.0 (
iPhone
; CPU
iPhone OS
15_6
like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko)
Version/
15.6
Mobile/15E148
Safari/
604.1
5.5.2.
Safari-specific tokens
safariVersion
decomposes
to the following:
majorVersion
>.<
minorVersion
", where
minorVersion
is a single digit.
safariPlatform
decomposes
to the following:
On desktop and larger iPad form factors, the
constant
Macintosh; Intel Mac OS X 10_15_7
".
On mobile platforms, including smaller iPad form factors
appleProduct
>; CPU <
mobileOSName
> <
iOSVersion
> like Mac OS X
".
Tokens
Description
appleProduct
Represents the marketing product name of the mobile device, which is one of
iPad
", "
iPhone
", and "
iPod
".
iOSVersion
Represents the iOS version number, delimited by an underscore (
for historical compatibility reasons
).
mobileOSName
constant
that is one of two values: "
OS
" (for iPad-like devices) or
iPhone OS
" (non-iPad-like devices).
webkitVersion
constant
that is one of two values: "
605.1.15
" (for larger devices,
including non-mini iPad) or "
604.1
" (for smaller mobile devices, including iPad
mini).
Acknowledgements
Thanks to Alan Cutter, Cameron McCormack, Chris Rebert, Chun-Min (Jeremy) Chen, Daniel Holbert,
David Håsäther, Domenic Denicola, Eric Portis, hexalys, Jean-Yves Perrier, Jacob Rossi, Karl Dubost,
Philip Jägenstedt, Rick Byers, Simon Pieters, Stanley Stuart, William Chen and Your Name Here for
feedback and contributions to this standard.
Thanks to Mounir Lamouri and Marcos Cáceres for defining the
ScreenOrientation
interface.
[screen-orientation]
Special thanks to Apple and the WebKit.org blog authors for providing initial descriptions of much
of the content defined in this specification.
This standard is written by
Mike Taylor
Google
miketaylr@google.com
).
Intellectual property rights
Copyright © WHATWG (Apple, Google, Mozilla, Microsoft). This work is licensed under a
Creative Commons Attribution 4.0
International License
. To the extent portions of it are incorporated into source code, such
portions in the source code are licensed under the
BSD 3-Clause License
instead.
This is the Living Standard. Those
interested in the patent-review version should view the
Living Standard Review Draft
Index
Terms defined by this specification
appleProduct
, in § 5.5.2
constant
, in § 5.1
decompose
, in § 5.1
deviceCompat
definition of
, in § 5.1.1
dfn for firefox
, in § 5.4.2
firefoxPlatform
, in § 5.4.2
firefoxVersion
, in § 5.4.2
geckoVersion
, in § 5.4.2
iOSVersion
, in § 5.5.2
majorVersion
, in § 5.1.1
minorVersion
, in § 5.1.1
mobileOSName
, in § 5.5.2
onorientationchange
attribute for HTMLBodyElement
, in § 4.2
attribute for Window
, in § 4.2
orientation
, in § 4.2
orientationchange
, in § 4.2
oscpu
, in § 5.1.1
platform
, in § 5.1.1
safariPlatform
, in § 5.5.2
safariVersion
, in § 5.5.2
token
, in § 5.1
touch-action
, in § 3.5.1
unifiedPlatform
, in § 5.3.2
-webkit-align-content
, in § 3.4.1
-webkit-align-items
, in § 3.4.1
-webkit-align-self
, in § 3.4.1
-webkit-animation
, in § 3.4.1
-webkit-animation-delay
, in § 3.4.1
-webkit-animation-direction
, in § 3.4.1
-webkit-animation-duration
, in § 3.4.1
-webkit-animation-fill-mode
, in § 3.4.1
-webkit-animation-iteration-count
, in § 3.4.1
-webkit-animation-name
, in § 3.4.1
-webkit-animation-play-state
, in § 3.4.1
-webkit-animation-timing-function
, in § 3.4.1
-webkit-backface-visibility
, in § 3.4.1
-webkit-background-clip
, in § 3.4.1
-webkit-background-origin
, in § 3.4.1
-webkit-background-size
, in § 3.4.1
-webkit-border-bottom-left-radius
, in § 3.4.1
-webkit-border-bottom-right-radius
, in § 3.4.1
-webkit-border-radius
, in § 3.4.1
-webkit-border-top-left-radius
, in § 3.4.1
-webkit-border-top-right-radius
, in § 3.4.1
-webkit-box
, in § 3.4.5
-webkit-box-align
, in § 3.4.4
-webkit-box-flex
, in § 3.4.4
-webkit-box-ordinal-group
, in § 3.4.4
-webkit-box-orient
, in § 3.4.4
-webkit-box-pack
, in § 3.4.4
-webkit-box-shadow
, in § 3.4.1
-webkit-box-sizing
, in § 3.4.1
-webkit-device-pixel-ratio
, in § 3.2.1
-webkit-filter
, in § 3.4.1
-webkit-flex
(property)
, in § 3.4.1
value for flex
, in § 3.4.5
-webkit-flex-basis
, in § 3.4.1
-webkit-flex-direction
, in § 3.4.1
-webkit-flex-flow
, in § 3.4.1
-webkit-flex-grow
, in § 3.4.1
-webkit-flex-shrink
, in § 3.4.1
-webkit-flex-wrap
, in § 3.4.1
-webkit-inline-box
, in § 3.4.5
-webkit-inline-flex
, in § 3.4.5
-webkit-justify-content
, in § 3.4.1
@-webkit-keyframes
, in § 3.1
-webkit-linear-gradient()
, in § 3.3.1
-webkit-mask
, in § 3.4.1
-webkit-mask-box-image
, in § 3.4.1
-webkit-mask-box-image-outset
, in § 3.4.1
-webkit-mask-box-image-repeat
, in § 3.4.1
-webkit-mask-box-image-slice
, in § 3.4.1
-webkit-mask-box-image-source
, in § 3.4.1
-webkit-mask-box-image-width
, in § 3.4.1
-webkit-mask-clip
, in § 3.4.1
-webkit-mask-composite
, in § 3.4.1
-webkit-mask-image
, in § 3.4.1
-webkit-mask-origin
, in § 3.4.1
-webkit-mask-position
, in § 3.4.1
-webkit-mask-repeat
, in § 3.4.1
-webkit-mask-size
, in § 3.4.1
-webkit-max-device-pixel-ratio
, in § 3.2.1
-webkit-min-device-pixel-ratio
, in § 3.2.1
-webkit-order
, in § 3.4.1
-webkit-perspective
, in § 3.4.1
-webkit-perspective-origin
, in § 3.4.1
-webkit-radial-gradient()
, in § 3.3.2
-webkit-repeating-linear-gradient()
, in § 3.3.3
-webkit-repeating-radial-gradient()
, in § 3.3.4
-webkit-text-fill-color
, in § 3.4.6.1
-webkit-text-size-adjust
, in § 3.4.2
-webkit-text-stroke
, in § 3.4.6.4
-webkit-text-stroke-color
, in § 3.4.6.2
-webkit-text-stroke-width
, in § 3.4.6.3
-webkit-transform
, in § 3.4.1
-webkit-transform-3d
, in § 3.2.2
-webkit-transform-origin
, in § 3.4.1
-webkit-transform-style
, in § 3.4.1
-webkit-transition
, in § 3.4.1
-webkit-transition-delay
, in § 3.4.1
-webkit-transition-duration
, in § 3.4.1
-webkit-transition-property
, in § 3.4.1
-webkit-transition-timing-function
, in § 3.4.1
webkitVersion
, in § 5.5.2
Terms defined by reference
[CSS-2025]
defines the following terms:
vendor prefix
[CSS-ALIGN-3]
defines the following terms:
align-content
align-items
align-self
justify-content
[CSS-ANIMATIONS-1]
defines the following terms:
@keyframes
animation
animation-delay
animation-direction
animation-fill-mode
animation-iteration-count
animation-name
animation-play-state
animation-timing-function
[CSS-ANIMATIONS-2]
defines the following terms:
animation-duration
[CSS-BACKGROUNDS-3]
defines the following terms:

background-clip
background-origin
background-size
[CSS-BORDERS-4]
defines the following terms:
border-bottom-left-radius
border-bottom-right-radius
border-radius
border-top-left-radius
border-top-right-radius
box-shadow
[CSS-CASCADE-5]
defines the following terms:
legacy name alias
[CSS-COLOR-4]
defines the following terms:
currentcolor
[CSS-COLOR-5]
defines the following terms:

[CSS-CONDITIONAL-3]
defines the following terms:
@media
[CSS-DISPLAY-3]
defines the following terms:
flex
[CSS-DISPLAY-4]
defines the following terms:
order
[CSS-FLEXBOX-1]
defines the following terms:
flex
flex-basis
flex-direction
flex-flow
flex-grow
flex-shrink
flex-wrap
inline-flex
[CSS-IMAGES-4]
defines the following terms:
gradient function
[CSS-MASKING-1]
defines the following terms:
mask
mask-border
mask-border-outset
mask-border-repeat
mask-border-slice
mask-border-source
mask-border-width
mask-clip
mask-composite
mask-image
mask-origin
mask-position
mask-repeat
mask-size
[CSS-SIZE-ADJUST-1]
defines the following terms:
text-size-adjust
[CSS-SIZING-3]
defines the following terms:
box-sizing
[CSS-SYNTAX-3]
defines the following terms:
at-rule
invalid
[CSS-TRANSFORMS-1]
defines the following terms:
transform
transform-origin
[CSS-TRANSFORMS-2]
defines the following terms:
backface-visibility
perspective
perspective-origin
transform-style
[CSS-TRANSITIONS-1]
defines the following terms:
transition
transition-delay
transition-duration
transition-property
transition-timing-function
[CSS-UI-4]
defines the following terms:
-webkit-appearance
[CSS-VALUES-4]
defines the following terms:

dppx
||
[CSS3-IMAGES-20110217]
defines the following terms:
linear-gradient
radial-gradient
repeating-linear-gradient
repeating-radial-gradient
[DOM]
defines the following terms:
fire an event
[FETCH]
defines the following terms:
header
[FILTER-EFFECTS-1]
defines the following terms:
filter
[GEOMETRY-1]
defines the following terms:
WebKitCSSMatrix
[HTML]
defines the following terms:
EventHandler
HTMLBodyElement
Window
active document
associated Document
body
event handler
event handler event type
relevant global object
[INFRA]
defines the following terms:
string
user agent
[MEDIAQUERIES-5]
defines the following terms:

media feature
resolution
[SCREEN-ORIENTATION]
defines the following terms:
ScreenOrientation
current orientation angle
[SVG2]
defines the following terms:
fill
stroke
[WEBIDL]
defines the following terms:
short
this
References
Normative References
[CSS-2025]
Chris Lilley; et al.
CSS Snapshot 2025
. URL:
[CSS-ALIGN-3]
Elika Etemad; Tab Atkins Jr..
CSS Box Alignment Module Level 3
. URL:
[CSS-ANIMATIONS-1]
David Baron; et al.
CSS Animations Level 1
. URL:
[CSS-ANIMATIONS-2]
David Baron; Brian Birtles.
CSS Animations Level 2
. URL:
[CSS-BACKGROUNDS-3]
Elika Etemad; Brad Kemper.
CSS Backgrounds and Borders Module Level 3
. URL:
[CSS-BORDERS-4]
Elika Etemad; et al.
CSS Borders and Box Decorations Module Level 4
. URL:
[CSS-CASCADE-5]
Elika Etemad; Miriam Suzanne; Tab Atkins Jr..
CSS Cascading and Inheritance Level 5
. URL:
[CSS-COLOR-4]
Tab Atkins Jr.; Chris Lilley; Lea Verou.
CSS Color Module Level 4
. URL:
[CSS-COLOR-5]
Chris Lilley; Una Kravets; Lea Verou.
CSS Color Module Level 5
. URL:
[CSS-CONDITIONAL-3]
Chris Lilley; David Baron; Elika Etemad.
CSS Conditional Rules Module Level 3
. URL:
[CSS-DISPLAY-3]
Elika Etemad; Tab Atkins Jr..
CSS Display Module Level 3
. URL:
[CSS-DISPLAY-4]
Elika Etemad; Tab Atkins Jr..
CSS Display Module Level 4
. URL:
[CSS-FLEXBOX-1]
Elika Etemad; Tab Atkins Jr.; Rossen Atanassov.
CSS Flexible Box Layout Module Level 1
. URL:
[CSS-IMAGES-4]
Elika Etemad; Tab Atkins Jr.; Lea Verou.
CSS Images Module Level 4
. URL:
[CSS-MASKING-1]
Dirk Schulze; Brian Birtles; Tab Atkins Jr..
CSS Masking Module Level 1
. URL:
[CSS-SIZE-ADJUST-1]
CSS Mobile Text Size Adjustment Module Level 1
. Editor's Draft. URL:
[CSS-SIZING-3]
Tab Atkins Jr.; Elika Etemad.
CSS Box Sizing Module Level 3
. URL:
[CSS-SYNTAX-3]
Tab Atkins Jr.; Simon Sapin.
CSS Syntax Module Level 3
. URL:
[CSS-TRANSFORMS-1]
Simon Fraser; et al.
CSS Transforms Module Level 1
. URL:
[CSS-TRANSFORMS-2]
Tab Atkins Jr.; et al.
CSS Transforms Module Level 2
. URL:
[CSS-TRANSITIONS-1]
Chris Marrin; et al.
CSS Transitions Module Level 1
. URL:
[CSS-VALUES-4]
Tab Atkins Jr.; Elika Etemad.
CSS Values and Units Module Level 4
. URL:
[CSS3-IMAGES-20110217]
Elika Etemad; Tab Atkins Jr..
CSS Image Values and Replaced Content Module Level 3
. URL:
[DOM]
Anne van Kesteren.
DOM Standard
. Living Standard. URL:
[FETCH]
Anne van Kesteren.
Fetch Standard
. Living Standard. URL:
[FILTER-EFFECTS-1]
Dirk Schulze; Dean Jackson.
Filter Effects Module Level 1
. URL:
[GEOMETRY-1]
Sebastian Zartner; Yehonatan Daniv.
Geometry Interfaces Module Level 1
. URL:
[HTML]
Anne van Kesteren; et al.
HTML Standard
. Living Standard. URL:
[HTTP-SEMANTICS]
R. Fielding; M. Nottingham; J. Reschke.
HTTP Semantics
. URL:
[INFRA]
Anne van Kesteren; Domenic Denicola.
Infra Standard
. Living Standard. URL:
[MEDIAQUERIES-4]
Tab Atkins Jr.; Florian Rivoal.
Media Queries Level 4
. URL:
[MEDIAQUERIES-5]
Tab Atkins Jr.; et al.
Media Queries Level 5
. URL:
[POINTEREVENTS2]
Matt Brubeck; et al.
Pointer Events
. URL:
[RFC2119]
S. Bradner.
Key words for use in RFCs to Indicate Requirement Levels
. March 1997. Best Current Practice. URL:
[SCREEN-ORIENTATION]
Marcos Caceres.
Screen Orientation
. URL:
[SVG2]
Amelia Bellamy-Royds; et al.
Scalable Vector Graphics (SVG) 2
. URL:
[WEBIDL]
Edgar Chen; Timothy Gu.
Web IDL Standard
. Living Standard. URL:
Informative References
[CSS-UI-4]
Tab Atkins Jr.; Florian Rivoal.
CSS Basic User Interface Module Level 4
. URL:
Property Index
Name
Value
Initial
Applies to
Inh.
%ages
Anim­ation type
Canonical order
Com­puted value
Media
-webkit-text-fill-color

currentcolor
all elements
yes
N/A
by computed value type
per grammar
an RGBA color
visual
-webkit-text-stroke
||
See individual properties
See individual properties
yes
N/A
See individual properties
per grammar
See individual properties
visual
-webkit-text-stroke-color

currentcolor
all elements
yes
N/A
by computed value type
per grammar
an RGBA color
visual
-webkit-text-stroke-width

all elements
yes
N/A
discrete
per grammar
absolute length
visual
touch-action
auto | none | [ [ pan-x | pan-left | pan-right ] || [ pan-y | pan-up | pan-down ] || pinch-zoom ] | manipulation
auto
all elements except: non-replaced inline elements, table rows, row groups, table columns, and column groups.
no
N/A
not animatable
per grammar
Same as specified value
visual
@media
Descriptors
Name
Value
Initial
Type
-webkit-device-pixel-ratio

range
-webkit-transform-3d

discrete
IDL Index
partial
interface
Window
readonly
attribute
short
orientation
attribute
EventHandler
onorientationchange
};
partial
interface
HTMLBodyElement
attribute
EventHandler
onorientationchange
};
MDN
@media/-webkit-device-pixel-ratio
In all current engines.
Firefox
63+
Safari
3+
Chrome
1+
Opera
Edge
79+
Edge (Legacy)
12+
IE
None
Firefox for Android
iOS Safari
1+
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
@media/-webkit-device-pixel-ratio
In all current engines.
Firefox
63+
Safari
3+
Chrome
1+
Opera
Edge
79+
Edge (Legacy)
12+
IE
None
Firefox for Android
iOS Safari
1+
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
@media/-webkit-device-pixel-ratio
In all current engines.
Firefox
63+
Safari
3+
Chrome
1+
Opera
Edge
79+
Edge (Legacy)
12+
IE
None
Firefox for Android
iOS Safari
1+
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
MDN
@media/-webkit-transform-3d
In all current engines.
Firefox
49+
Safari
4+
Chrome
2+
Opera
Edge
79+
Edge (Legacy)
12+
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
MDN
-webkit-text-fill-color
In all current engines.
Firefox
49+
Safari
3+
Chrome
1+
Opera
Edge
79+
Edge (Legacy)
12+
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
15+
MDN
-webkit-text-stroke-color
In all current engines.
Firefox
49+
Safari
3+
Chrome
1+
Opera
Edge
79+
Edge (Legacy)
15+
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
15+
MDN
-webkit-text-stroke-width
In all current engines.
Firefox
49+
Safari
3+
Chrome
1+
Opera
Edge
79+
Edge (Legacy)
15+
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
38+
Samsung Internet
Opera Mobile
15+
MDN
-webkit-text-stroke
In all current engines.
Firefox
49+
Safari
3+
Chrome
4+
Opera
Edge
79+
Edge (Legacy)
15+
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
4+
Samsung Internet
Opera Mobile
MDN
touch-action
In all current engines.
Firefox
52+
Safari
13+
Chrome
36+
Opera
Edge
79+
Edge (Legacy)
12+
IE
11
Firefox for Android
52+
iOS Safari
9.3+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile