JPEG XL is now enabled by default, with lossy and lossless compression, transparency, animation, and HDR. CSS typed arithmetic lets calc() divide values with different units, like 100vw / 1px, to get a unitless number. Notifications gain a navigate option with a URL to open on click, and WebTransport adds getStats(). Behind flags: the random() function, corner-shape, and import defer.
developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/158