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rex unit

Newly Available (since 2026-01-13)
Expected to be Widely Available on 2028-07-13

The rex CSS length unit is a font-relative length that is equal to the x-height of the root element.

Browser support

  • Chrome 111 Released on 2023-03-07
  • Chrome Android 111 Released on 2023-03-07
  • Edge 111 Released on 2023-03-13
  • Firefox 147 Released on 2026-01-13
  • Firefox for Android 147 Released on 2026-01-13
  • Safari 17.2 Released on 2023-12-11
  • Safari on iOS 17.2 Released on 2023-12-11

MDN documentation

Specifications

Web Platform Tests (WPT)

View the latest WPT test results for this feature

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