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Case-sensitive attribute selectorLimited availability

The s identifier in a CSS attribute selector matches attribute values case-sensitively in document languages like HTML where attribute values are case-insensitive.

Not yet supported in all major browsers — check the table and provide a fallback.

How to use ↓Compare browsers

Browser support

DesktopChrome
✕Not supportedup to 155
Current: 155
Edge
✕Not supportedup to 154
Current: 154
Firefox
1–65Not supported
66+Supportedsince Mar 19, 2019
Current: 157
Safari
1–26.6Not supported
27+Supportedsince Sep 14, 2026
Current: 27
MobileChrome Android
✕Not supportedup to 155
Current: 155
Firefox Android
4–65Not supported
66+Supportedsince Mar 19, 2019
Current: 157
Safari iOS
1–26.6Not supported
27+Supportedsince Sep 14, 2026
Current: 27

How to use

Not supported in Chrome, Edge, Chrome Android. Use feature detection below and provide a fallback (or a polyfill) for those browsers.

Example

Full syntax and examples are on MDN — see the links below.

Feature detection

CSS · check before using
@supports selector(:attribute) {
  /* styles that use :attribute */
}

/* or in JavaScript */
if (CSS.supports("selector(:attribute)")) {
  // use it
}

Specification