Web platform features explorer

📃 July 2025 release notes

Widely available

The following features are now widely available:

  • MathML: MathML, or the Mathematical Markup Language, describes mathematical notation, such as expressions and formulas. Also known as MathML Core.

New in Firefox

The following features are now available in Firefox:

  • <dialog closedby>: The closedby HTML attribute for <dialog> sets which user actions close a dialog. For example, closedby="any" allows the dialog to be closed by clicking outside of it.
  • font-variant-emoji: The font-variant-emoji CSS property sets the default presentation for emoji characters.

New in Firefox for Android

The following features are now available in Firefox for Android:

  • <dialog closedby>: The closedby HTML attribute for <dialog> sets which user actions close a dialog. For example, closedby="any" allows the dialog to be closed by clicking outside of it.
  • font-variant-emoji: The font-variant-emoji CSS property sets the default presentation for emoji characters.