Mozilla shipped Firefox 157 this week, and the headline feature is Nova — a complete visual overhaul that the team is calling the browser's biggest redesign since 2021. If you've been running Firefox Nightly, you've already seen it. For everyone else, it started rolling out with the stable release and brings a noticeably different look to one of the web's longest-running browsers.
What Nova Actually Changes
The most immediate change is the rounding. Nova introduces heavily rounded corners across tabs, toolbars, menus, and panels, combined with subtle color gradients that give surfaces a bit more depth than Proton's flatter approach. It's a design language that feels more at home alongside macOS Sequoia and Windows 11 than Firefox's previous aesthetic did.
Beyond the geometry, Firefox 157 ships with 12 built-in themes, each offered in both light and dark variants, and a new theme picker to browse them. The New Tab page, Private Browsing interface, and sidebar have all been updated to match. The sidebar itself gets a more prominent role in Nova, with vertical tabs now treated as a primary layout option rather than an experimental one.
Compact Mode Returns
One of the changes getting the most attention from power users is the return of Compact Mode. Mozilla removed it in Firefox 89 when Proton shipped, and its absence remained a recurring complaint for years. Nova brings it back, reducing tab and toolbar spacing to give websites more vertical breathing room. There's also an automatic compact option for smaller screens, which is useful for anyone working with Firefox in a tiled or half-screen configuration.
Cyber Insider reports that Mozilla says the visual changes come without a performance penalty — the rendering pipeline underneath is unchanged, so you're not trading frames for aesthetics.
Under the Hood: AV1 Hardware Decoding
On the technical side, Firefox 157 also enables WebRTC hardware AV1 decode, which means video calls using AV1 encoding — increasingly the default for modern conferencing tools — will offload decoding to the GPU rather than the CPU. 9to5Linux notes this is particularly meaningful for Linux users on supported hardware, where software AV1 decoding has historically been a significant CPU drain during long calls.
The Bigger Picture
Firefox's market share has been declining for years, and Mozilla has been transparent about the financial pressure that comes with running a browser on volunteer-scale market presence. Nova is partly a product bet that a more polished interface will help retention, but it's also a statement that Mozilla still has the capacity to ship something genuinely new rather than iterative.
Whether Nova moves the needle on adoption is an open question. Design refreshes rarely drive browser switching on their own. But for existing Firefox users who've been waiting for something to feel modern again — especially after Chrome and Safari's recent visual updates — 157 is a meaningful release. It's available now for download across Windows, macOS, and Linux from Mozilla's official site.