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Use CSS @supports to check whether a browser accepts a particular CSS declaration or selector, then apply enhanced styles only when that check passes. Put a reliable baseline first: a positive result confirms that the browser accepts the tested syntax, not that the feature works perfectly in every situation.
Check support for a CSS property and value
Write a parenthesized property-value declaration after @supports. Place the rule at the stylesheet’s top level, or inside another conditional group rule.
.card {
display: block;
}
@supports (display: grid) {
.card-list {
display: grid;
grid-template-columns: repeat(3, 1fr);
}
}The ordinary display: block rule is the baseline. Browsers that pass the query also receive the grid enhancement. Browsers that do not recognize the declaration ignore the conditional block.
Test the specific value your design needs. A check that a property accepts some value does not establish that it accepts a newer value you rely on. For example, checking a familiar value of a property is not equivalent to checking the particular newer value used by the design. See MDN’s guide to using feature queries.
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Combine conditions or provide alternatives
Use and when every condition must pass, or when any one of the alternatives is sufficient, and not when you want to test for a condition that fails. Parentheses group expressions.
Require every feature
@supports (display: grid) and (gap: 1rem) {
.card-list {
display: grid;
gap: 1rem;
}
}The block applies only if both declarations are supported.
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Accept either declaration
@supports (text-stroke: 1px) or (-webkit-text-stroke: 1px) {
.outlined-heading {
-webkit-text-stroke: 1px;
}
}This query passes if the browser supports at least one tested declaration. The styles inside the block should still use declarations appropriate to the implementations you intend to support.
Target browsers that fail a check
@supports not (display: grid) {
.card-list {
/* Styles for browsers that fail this check */
}
}Use this for a specific unsupported-feature treatment. A sound baseline followed by an enhancement is often simpler than maintaining a separate unsupported-browser branch.
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Check whether a browser accepts a selector
Use the selector() form when the question is about selector syntax, rather than a property-value pair. For example, this checks whether the browser accepts a selector using :has():
@supports selector(:has(a)) {
.card:has(a) {
/* Styles that depend on :has() */
}
}The query tests the selector syntax you give it. Make that test representative of the syntax your stylesheet actually depends on. MDN also documents feature queries for at-rules and font technologies or formats in its @supports reference.
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Know what a passing query proves
A true feature query means the user agent accepts the tested syntax as valid. It does not prove the implementation is bug-free, complete, or suitable for every use case; nor does the query identify partial implementation behavior. For high-impact styling or behavior, test the actual result in the real browser versions and devices that matter. MDN explains this distinction in Using feature queries.
Feature queries are optional when ordinary CSS already gives you a safe fallback: browsers generally ignore CSS they do not recognize. Use @supports when it provides a meaningful progressive-enhancement strategy or when you need a deliberate branch for browsers that fail a check.
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Check CSS support from JavaScript
JavaScript can evaluate CSS support conditions with CSS.supports(). Use the dedicated API reference and its compatibility data before relying on it for particular browser versions; a CSS query and a JavaScript support check do not replace testing actual behavior.
Or skip the browser setup:
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Frequently Asked Questions
Can @supports tell me whether a browser supports an entire CSS feature correctly?
No. A passing query confirms that the tested syntax is accepted; test actual behavior in the browsers and devices that matter.
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No. Browsers generally ignore unrecognized CSS. Use a query when it enables a useful enhancement or a deliberate fallback.
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