Mozilla released Firefox 157 to its stable channel on Thursday, delivering a redesigned interface with rounded tabs, refreshed color palettes and a reorganised toolbar layout to hundreds of millions of desktop users worldwide.

The update marks the most significant visual change to the browser since Mozilla's 2021 Proton redesign. According to Mozilla's release notes, the new layout adjusts tab shapes, spacing and theme handling, and introduces refreshed light and dark modes intended to modernise the browser's appearance across Windows, macOS and Linux.

Mozilla previewed the changes through its Nightly and Beta channels before the general rollout. The redesign accompanies performance and memory improvements, alongside continued work on vertical tabs and sidebar customisation that Mozilla has promoted as differentiators against Google Chrome.

The release lands as Mozilla fights to defend desktop market share that has fallen below three percent globally, according to StatCounter data. Firefox remains central to Mozilla's identity even as the organisation faces uncertainty over its search revenue arrangement with Google, which is subject to ongoing US antitrust remedies.

Mozilla said the update would roll out automatically to existing users over the following days, with a manual download available immediately from its website.