@supports

The @supports CSS at-rule lets you specify declarations that depend on a browser's support for one or more specific CSS features. This is called a feature query. The rule may be placed at the top level of your code or nested inside any other conditional group at-rule.

@supports (display: grid) {
  div {
    display: grid;
  }
}
@supports not (display: grid) {
  div {
    float: right;
  }
}

In JavaScript, @supports can be accessed via the CSS object model interface CSSSupportsRule.

Syntax

The @supports at-rule associates a block of statements with a supports condition. The supports condition consists of one or more name-value pairs combined by conjunctions (and), disjunctions (or), and/or negations (not). Precedence of operators can be defined with parentheses.

Declaration syntax

The most basic supports condition is a simple declaration (a property name followed by a value, separated by a colon). The declaration must be surrounded by parentheses. The following example returns true if the browser's transform-origin property considers 5% 5% valid:

@supports (transform-origin: 5% 5%) {}

Function syntax

The second basic supports condition is a supports function, the syntax for these is supported by all browsers, but the functions themselves are still being standardized.

selector()

Tests if the browser supports the tested selector syntax. The following example returns true if the browser supports the child combinator:

@supports selector(A > B) {}

The not operator

The not operator can precede any expression to create a new expression, resulting in the negation of the original one. The following example returns true if the browser's transform-origin property doesn't consider 10em 10em 10em valid:

@supports not (transform-origin: 10em 10em 10em) {}

As with any operator, the not operator can be applied to a declaration of any complexity. The following examples are both valid:

@supports not (not (transform-origin: 2px)) {}
@supports (display: grid) and (not (display: inline-grid)) {}

Note: There is no need to enclose the not operator between two parentheses at the top level. To combine it with other operators, like and and or, the parentheses are required.

The and operator

The and operator creates a new expression from the conjunction of two shorter expressions. It returns true only if both of the shorter expressions are also true. The following example returns true if and only if the two shorter expressions are simultaneously true:

@supports (display: table-cell) and (display: list-item) {}

Multiple conjunctions can be juxtaposed without the need of more parentheses. The following are both equivalent:

@supports (display: table-cell) and (display: list-item) and (display:run-in) {}
@supports (display: table-cell) and ((display: list-item) and (display:run-in)) {}

The or operator

The or operator creates a new expression from the disjunction of two shorter expressions. It returns true if one or both of the shorter expressions is also true. The following example returns true if at least one of the two shorter expressions is true:

@supports (transform-style: preserve) or (-moz-transform-style: preserve) {}

Multiple disjunctions can be juxtaposed without the need of more parentheses. The following are both equivalent:

@supports (transform-style: preserve) or (-moz-transform-style: preserve) or
          (-o-transform-style: preserve) or (-webkit-transform-style: preserve) {}

@supports (transform-style: preserve-3d) or ((-moz-transform-style: preserve-3d) or
          ((-o-transform-style: preserve-3d) or (-webkit-transform-style: preserve-3d))) {}

Note: When using both and and or operators, the parentheses must be used to define the order in which they apply. Otherwise, the condition is invalid and the whole rule is ignored.

Formal syntax

@supports <supports-condition> {
  <group-rule-body>
}

where
<supports-condition> = not <supports-in-parens> | <supports-in-parens> [ and <supports-in-parens> ]* | <supports-in-parens> [ or <supports-in-parens> ]*

where
<supports-in-parens> = ( <supports-condition> ) | <supports-feature> | <general-enclosed>

where
<supports-feature> = <supports-decl> | <supports-selector-fn>
<general-enclosed> = [ <function-token> <any-value> ) ] | ( <ident> <any-value> )

where
<supports-decl> = ( <declaration> )
<supports-selector-fn> = selector( <complex-selector> )

where
<complex-selector> = <compound-selector> [ <combinator>? <compound-selector> ]*

where
<compound-selector> = [ <type-selector>? <subclass-selector>* [ <pseudo-element-selector> <pseudo-class-selector>* ]* ]!
<combinator> = '>' | '+' | '~' | [ '|' ]

where
<type-selector> = <wq-name> | <ns-prefix>? '*'
<subclass-selector> = <id-selector> | <class-selector> | <attribute-selector> | <pseudo-class-selector>
<pseudo-element-selector> = ':' <pseudo-class-selector>
<pseudo-class-selector> = ':' <ident-token> | ':' <function-token> <any-value> ')'

where
<wq-name> = <ns-prefix>? <ident-token>
<ns-prefix> = [ <ident-token> | '*' ]? |
<id-selector> = <hash-token>
<class-selector> = '.' <ident-token>
<attribute-selector> = '[' <wq-name> ']' | '[' <wq-name> <attr-matcher> [ <string-token> | <ident-token> ] <attr-modifier>? ']'

where
<attr-matcher> = [ '~' | | | '^' | '$' | '*' ]? '='
<attr-modifier> = i | s

Examples

Testing for the support of a given CSS property

@supports (animation-name: test) {
  … /* CSS applied when animations are supported without a prefix */
  @keyframes { /* Other at-rules can be nested inside */
    …
  }
}

Testing for the support of a given CSS property or a prefixed version

@supports ((perspective: 10px) or (-moz-perspective: 10px) or (-webkit-perspective: 10px) or
         (-ms-perspective: 10px) or (-o-perspective: 10px)) {
  … /* CSS applied when 3D transforms, prefixed or not, are supported */
}

Testing for the non-support of a specific CSS property

@supports not ((text-align-last: justify) or (-moz-text-align-last: justify)) {
  … /* CSS to provide fallback alternative for text-align-last: justify */
}

Testing for the support of custom properties

@supports (--foo: green) {
  body {
    color: var(--varName);
  }
}

Testing for the support of a selector (eg. :is())

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

/* This rule won't be applied in browsers which don't support :is() */
:is(ul, ol) > li {
  … /* CSS applied when the :is(…) selector is supported */
}

@supports not selector(:is(a, b)) {
  /* Fallback for when :is() is unsupported */
  ul > li,
  ol > li {
    … /* The above expanded for browsers which don't support :is(…) */
  }
}

@supports selector(:nth-child(1n of a, b)) {
  /* This rule needs to be inside the @supports block, otherwise
     it will be partially applied in browsers which don't support
     the `of` argument of :nth-child(…) is supported */
  :is(:nth-child(1n of ul, ol) a,
  details > summary) {
    … /* CSS applied when the :is(…) selector and
         the `of` argument of :nth-child(…) are both supported */
  }
}

Specifications

Specification Status Comment
CSS Conditional Rules Module Level 4
The definition of '@supports' in that specification.
Editor's Draft Adds the selector() function.
CSS Conditional Rules Module Level 3
The definition of '@supports' in that specification.
Candidate Recommendation Initial definition.

Browser compatibility

DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
@supportsChrome Full support 28Edge Full support 12Firefox Full support 22
Full support 22
No support 17 — 22
Disabled
Disabled From version 17 until version 22 (exclusive): this feature is behind the layout.css.supports-rule.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
IE No support NoOpera Full support 12.1Safari Full support 9WebView Android Full support ≤37Chrome Android Full support 28Firefox Android Full support 22
Full support 22
No support 17 — 22
Disabled
Disabled From version 17 until version 22 (exclusive): this feature is behind the layout.css.supports-rule.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
Opera Android Full support 12.1Safari iOS Full support 9Samsung Internet Android Full support 1.5
selector()Chrome Full support 83Edge Full support 83Firefox Full support 69
Full support 69
Full support 64
Disabled
Disabled From version 64: this feature is behind the layout.css.supports-selector.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
IE No support NoOpera Full support 69Safari No support No
Notes
No support No
Notes
Notes See bug 199237
WebView Android Full support 83Chrome Android Full support 83Firefox Android Full support 64
Disabled
Full support 64
Disabled
Disabled From version 64: this feature is behind the layout.css.supports-selector.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
Opera Android No support No
Notes
No support No
Notes
Notes See bug 979041.
Safari iOS No support No
Notes
No support No
Notes
Notes See bug 199237
Samsung Internet Android No support No
Notes
No support No
Notes
Notes See bug 979041.

Legend

Full support
Full support
No support
No support
See implementation notes.
See implementation notes.
User must explicitly enable this feature.
User must explicitly enable this feature.

See also