:is() CSS pseudo-class
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2021.
The :is() CSS pseudo-class function takes a selector list as its argument, and selects any element that can be selected by one of the selectors in that list. This is useful for writing large selectors in a more compact form.
Note:
Originally named :matches() (and :any()), this selector was renamed to :is() in CSSWG issue #3258.
Try it
ol {
list-style-type: upper-alpha;
color: darkblue;
}
:is(ol, ul, menu:unsupported) :is(ol, ul) {
color: green;
}
:is(ol, ul) :is(ol, ul) ol {
list-style-type: lower-greek;
color: chocolate;
}
<ol>
<li>Saturn</li>
<li>
<ul>
<li>Mimas</li>
<li>Enceladus</li>
<li>
<ol>
<li>Voyager</li>
<li>Cassini</li>
</ol>
</li>
<li>Tethys</li>
</ul>
</li>
<li>Uranus</li>
<li>
<ol>
<li>Titania</li>
<li>Oberon</li>
</ol>
</li>
</ol>
Syntax
:is(<forgiving-selector-list>) {
/* ... */
}
Parameters
The :is() pseudo-class requires a selector list, a comma-separated list of one or more selectors as its argument. The list must not contain a pseudo-element, but any other simple, compound, and complex selectors are allowed.
Difference between :is() and :where()
The difference between the two is that :is() counts towards the specificity of the overall selector (it takes the specificity of its most specific argument), whereas :where() has a specificity value of 0. This is demonstrated by the example on the :where() reference page.
Forgiving Selector Parsing
The specification defines :is() and :where() as accepting a forgiving selector list.
In CSS when using a selector list, if any of the selectors are invalid then the whole list is deemed invalid. When using :is() or :where() instead of the whole list of selectors being deemed invalid if one fails to parse, the incorrect or unsupported selector will be ignored and the others used.
:is(:valid, :unsupported) {
/* … */
}
Will still parse correctly and match :valid even in browsers which don't support :unsupported, whereas:
:valid,
:unsupported {
/* … */
}
Will be ignored in browsers which don't support :unsupported even if they support :valid.
Examples
Simplifying list selectors
The :is() pseudo-class can greatly simplify your CSS selectors. For example, take the following CSS:
/* 3-deep (or more) unordered lists use a square */
ol ol ul,
ol ul ul,
ol menu ul,
ol dir ul,
ol ol menu,
ol ul menu,
ol menu menu,
ol dir menu,
ol ol dir,
ol ul dir,
ol menu dir,
ol dir dir,
ul ol ul,
ul ul ul,
ul menu ul,
ul dir ul,
ul ol menu,
ul ul menu,
ul menu menu,
ul dir menu,
ul ol dir,
ul ul dir,
ul menu dir,
ul dir dir,
menu ol ul,
menu ul ul,
menu menu ul,
menu dir ul,
menu ol menu,
menu ul menu,
menu menu menu,
menu dir menu,
menu ol dir,
menu ul dir,
menu menu dir,
menu dir dir,
dir ol ul,
dir ul ul,
dir menu ul,
dir dir ul,
dir ol menu,
dir ul menu,
dir menu menu,
dir dir menu,
dir ol dir,
dir ul dir,
dir menu dir,
dir dir dir {
list-style-type: square;
}
You can replace it with:
/* 3-deep (or more) unordered lists use a square */
:is(ol, ul, menu, dir) :is(ol, ul, menu, dir) :is(ul, menu, dir) {
list-style-type: square;
}
Simplifying section selectors
The :is() pseudo-class is particularly useful when dealing with HTML sections and headings. Since <section>, <article>, <aside>, and <nav> are commonly nested together, without :is(), styling them to match one another can be tricky.
For example, without :is(), styling all the h1 elements at different depths could be very complicated:
/* Level 0 */
h1 {
font-size: 30px;
}
/* Level 1 */
section h1,
article h1,
aside h1,
nav h1 {
font-size: 25px;
}
/* Level 2 */
section section h1,
section article h1,
section aside h1,
section nav h1,
article section h1,
article article h1,
article aside h1,
article nav h1,
aside section h1,
aside article h1,
aside aside h1,
aside nav h1,
nav section h1,
nav article h1,
nav aside h1,
nav nav h1 {
font-size: 20px;
}
/* Level 3 */
/* don't even think about it! */
Using :is(), though, it's much easier:
/* Level 0 */
h1 {
font-size: 30px;
}
/* Level 1 */
:is(section, article, aside, nav) h1 {
font-size: 25px;
}
/* Level 2 */
:is(section, article, aside, nav) :is(section, article, aside, nav) h1 {
font-size: 20px;
}
/* Level 3 */
:is(section, article, aside, nav)
:is(section, article, aside, nav)
:is(section, article, aside, nav)
h1 {
font-size: 15px;
}
:is() does not select pseudo-elements
The :is() pseudo-class does not match pseudo-elements. So rather than this:
some-element:is(::before, ::after) {
display: block;
}
or this:
:is(some-element::before, some-element::after) {
display: block;
}
instead do:
some-element::before,
some-element::after {
display: block;
}
Specifications
| Specification |
|---|
| Selectors Level 4 # matches-pseudo |
Browser compatibility
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:is()
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Support for forgiving selector list
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Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- Uses a non-standard name
- Has more compatibility info.
See also
:where()- Like:is(), but with 0 specificity.- Selector list
- Web components