Firefox news — Web Standards

September 30
Firefox 157 release notes for developers
at-rule() in @supports, a chain value for overscroll-behavior, and Web Animations fixes.
September 24
One SVG, nine posters: CSS link-parameters
An external SVG takes its colors from the page, and keeps its own when nothing is passed in.
September 15
Firefox 156 release notes for developers
Substitution functions in DevTools, priority-preserving yields, and Promise.try() pass-through.
September 2
Firefox 155 release notes for developers
attr() for any property, the progress() and alpha() functions, font-width, and Promise.allKeyed().
August 25
Intent to ship: JPEG XL
Firefox ships the format with the Rust jxl-rs decoder, progressive rendering, and lossless wins.
August 18
Firefox 154 release notes for developers
sibling-index(), text-box-trim, four new Iterator methods, and unprefixed line-clamp behind a flag.
July 22
Firefox 153 release notes for developers
Intl.Locale info methods, IndexedDB getAllRecords(), source phase imports, and WebAssembly JSPI.
June 18
Context-aware headings in HTML
How headingoffset shifts heading levels in the accessibility tree without changing tags.
June 17
Firefox 152 release notes for developers
field-sizing for form controls, Notification actions, and pointer lock unadjustedMovement.
May 19
Firefox 151 release notes for developers
@container style() queries, Document Picture-in-Picture, desktop Web Serial, and keyboardLock.
May 15
Browsers treat big sites differently
How Safari and Firefox quietly patch the web to keep big sites working.
April 21
Firefox 150 release notes for developers
New CSS features, media pseudo-classes, animation range, and ariaNotify().