Firefox 157 debuts Nova design and hardware AV1 decoding for WebRTC calls

Final Firefox 157 packages began appearing on Mozilla's servers on Monday, September 28, bringing the stable version of the redesign internally known as Project Nova. The update changes the browser's visible interface — tabs, sidebar, menus, icons, colors, and spacing — and introduces video improvements, including hardware AV1 decoding for compatible WebRTC calls.

The availability of the binaries was confirmed by independent technical publications. Distribution is not simultaneous for everyone, however: Windows and macOS users should receive the automatic update gradually, while Linux availability depends on each distribution's repositories. A completed package on the download servers therefore does not mean the update button will immediately appear on every computer.

Nova changes the interface without replacing Firefox's identity

Mozilla introduced Nova in May as a renewal of Firefox's visual foundation rather than a separate browser. In Firefox 157, the change appears in softer-shaped tabs, more rounded components, revised icons, and a fire-inspired palette with purple tones and a highlight around the active tab. New built-in themes offer light and dark variants, and the shared visual language extends to the sidebar and panels.

Compact mode also returns, reducing the space used by tabs and toolbar controls. The practical result for laptops, split windows, and smaller displays is more vertical room for page content. Mozilla says the new foundation is intended to make tab groups, split view, and vertical tabs easier to reach, although the availability of individual features can still depend on configuration and staged rollout.

The broader project also includes reorganized settings designed to make privacy controls and optional feature controls easier to find. That is Mozilla's stated direction for Nova; it does not mean every capability described in the roadmap arrived exclusively with Firefox 157.

Hardware AV1 reduces reliance on the CPU during calls

The most consequential technical change concerns WebRTC, the browser technology used by many video-conferencing services. Until this release, Firefox decoded incoming AV1 video in WebRTC calls through software. Firefox 157 can transfer that work to a supported device's hardware video decoder.

In practice, the change can lower CPU load and power consumption during calls that actually use AV1, but the benefit is not universal. It depends on the processor or GPU, drivers, operating system, and the codec negotiated by the calling service. On systems without the required support, the browser can still fall back to software decoding.

The release also fixes HDR video that could look washed out or gray in some 8-bit formats on Windows, prevents the Windows taskbar from remaining visible over fullscreen video, and improves audio-video synchronization after repeated playback-speed changes. These changes are less obvious than Nova, but they matter for people who use the browser as both a media player and a communications tool.

The update changes a default search option but preserves choice

Firefox 157 removes Amazon from the list of built-in search engines. The change does not block the website or prevent searches: users can still add it manually as a custom search engine. The release also adjusts keyboard navigation in the address bar and expands localized suggestions to more European countries.

Taken together, Firefox 157 is more than a cosmetic update. Nova establishes a base for future interface changes, while hardware AV1 and the playback fixes address concrete processing costs and video inconsistencies. The final impact will depend both on how users respond to the redesign and on hardware coverage and rollout speed across platforms.