Web platform features explorer - rlh unit

Web platform features explorer

The rlh CSS length unit is a font-relative length relative to the line height of root element.

Status

Baseline Widely Available (since 2026-05-21)

MDN documentation

Rlh, in `<length>` CSS type

Specifications

CSS Values and Units Module Level 4 (#font-relative-lengths), from Cascading Style Sheets (CSS) Working Group (W3C).

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 120 Released on 2023-11-21
Firefox for Android 120 Released on 2023-11-21
Safari 16.4 Released on 2023-03-27
Safari on iOS 16.4 Released on 2023-03-27

Usage (according to Chrome Platform Status)

~0.003% of page loads. More data at chromestatus.com.

Web Platform Tests (WPT)

View the latest WPT test results for this feature

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