Firefox 157 arrived September 29, and most of what’s changed is visible the moment you open it. Mozilla calls it the browser’s biggest visual refresh in years: toolbars, the sidebar, menus and individual features all rebuilt on an updated design system.
The cosmetic changes are easy to take or leave. The structural ones will affect daily use whether you asked for them or not.
What’s New
The updated sidebar is now on for everyone. Anyone still running the previous version keeps a similar layout, with the panel switcher at the top of the sidebar, but the “Show sidebar” option has been removed from Settings entirely. Users who want the old design can set sidebar.revamp to false in about:config which also turns off vertical tabs. Mozilla says that preference will remain available until the end of 2027, a deadline worth noting.
Amazon is no longer a built-in search engine. It can still be added manually as a custom search engine in search settings. Firefox Suggest, meanwhile, expands into 16 more European markets: Austria, Belgium, Czech Republic, Denmark, Finland, Hungary, Ireland, Luxembourg, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden and Switzerland. It’s controlled from the Firefox Suggest settings.
A new security warning. Firefox now flags when it has been set up to record its encryption keys, a configuration that could let other software on the machine read encrypted web traffic. The warning appears in the site information panel, behind the shield icon in the address bar, and in Settings.
Also new: built-in themes with light and dark variants, a compact mode that tightens toolbar and tab spacing for smaller screens and split-screen layouts, and hardware AV1 decoding for WebRTC video calls on devices that support it, replacing software decoding.
What’s Changed
The fix list is long and mostly mundane. Video from phones and tablets no longer shows up sideways or upside down in WebRTC calls. 8-bit HDR videos on Windows stop looking dull and gray. Audio and video stay in sync when you repeatedly change playback speed. The vertical tabs sidebar reappears when the cursor hits the screen edge in full screen, and the Windows taskbar no longer sits over full-screen video.
Two smaller interface tweaks: pressing Tab now jumps straight to the text field in the address bar and search bar instead of stopping on the search engine button first — Shift+Tab still reaches it — and page dialogs, color and date pickers and autocomplete drop-downs now follow the page’s light or dark color scheme.
If the new sidebar isn’t for you, the about:config switch is your only route back, and it comes with an expiry date.
If you’re a new firefox user, you can download Firefox Right now at Firefox Official Site
