This article provides information about the changes in Firefox 157 that affect developers. Firefox 157 was released on September 29, 2026.

NEW (nobody) in Core - CSS Parsing and Computation. Last updated 2026-09-14.

CSS is getting a random() function that lets you set properties with a random value, opening up a ton of interesting creative possibilities. In this article…

Because I haven't published anything to it since August 31. And no one else has either. That's not a super long time to go silent but it is for a site that

Gecko: Intent to Prototype: CSS random() math function

Gecko: Intent to Prototype: CSS at-rule() function for @supports

Gecko: Intent to Ship: Advanced CSS attr() function.

Gecko: Intent to Prototype: CSS Typed Arithmetic

RESOLVED (sajidanwar94) in Core - Layout: Block and Inline. Last updated 2026-07-15.

NEW (nobody) in DevTools - Inspector: Rules. Last updated 2025-10-28.

Gecko: Intent to Prototype: sibling-index() and sibling-count()

Financement participatif organisé par Sorosa - Collecte de soutien aux personnes exilées

This article provides information about the changes in Firefox 150 that affect developers. Firefox 150 was released on April 21, 2026.

RESOLVED (jfkthame) in Core - CSS Parsing and Computation. Last updated 2026-04-14.

A chaotic colour-matching game. Drag to shift hue and lightness to match the target. 10 rounds. The clock is ticking.

CSS light-dark() is being extended to support images.