Visual Changes in the Firefox 89 Proton User Interface

In June 2021, Mozilla released version 89 of the Firefox web browser, introducing a major visual overhaul known as the "Proton" user interface. This article outlines the specific visual modifications implemented with the Proton update, covering the transition to floating tabs, the decluttered navigation toolbar, consolidated menus, modernized notification prompts, and refreshed color palettes.

Floating, Rounded Tabs

The most noticeable change in the Proton interface was the complete redesign of the tab bar. Previously, tabs were attached directly to the navigation bar with sharp, squared edges. Proton replaced these with "floating" tabs that feature rounded corners and sit completely detached from the toolbar below them.

The active tab was given a distinct button-like appearance with a subtle drop shadow to clearly separate it from inactive tabs. Inactive tabs no longer had vertical divider lines between them, creating a cleaner, unified look across the top of the browser. Additionally, the tab height was slightly increased, and media controls were integrated directly into the tab; when a tab plays audio, a secondary line of text appears beneath the page title indicating that audio is playing, which doubles as a mute button when hovered over.

Mozilla aimed to reduce visual noise in the main navigation area by removing redundant icons and updating the remaining ones with lighter, more modern line art.

The "Page Actions" menu—previously represented by three dots inside the right side of the address bar—was completely removed. Frequently used tools from that menu, such as the screenshot tool and bookmark star, were either kept directly in the address bar or moved to the right-click context menu. On the left side of the address bar, the tracking protection shield, site security padlock, and permission icons were visually softened and spaced out for better readability.

Consolidated Application and Context Menus

The main application menu (the "hamburger" menu on the far right of the toolbar) underwent a strict reorganization to eliminate clutter. Mozilla removed all iconography from this menu, leaving only text labels. This change was made to help users scan the menu faster without being distracted by dozens of different icons.

Rarely used items were removed from the main menu entirely, while related features were grouped together using subtle horizontal divider lines. Context menus (accessed by right-clicking) also received this treatment, featuring rounded corners, increased padding between text lines, and the removal of unnecessary options.

Modernized Prompts and Notifications

Pop-ups, alerts, and permission prompts were redesigned to match the softer geometry of the new tab bar. When a website requests access to a user's microphone, camera, or location, the resulting prompt now features rounded corners and a softer background color.

Browser-level modal dialogs, such as the "Clear Recent History" or "Print" windows, were moved from dead-center pop-ups to slide-down overlays attached to the top navigation bar, creating a more cohesive connection with the active webpage.

Refreshed Color Palettes and Themes

The Proton update introduced a revamped color system for Firefox’s built-in themes. The default Light theme was made brighter with softer gray accents, while the Dark theme shifted away from its previous blue-tinted slate colors in favor of deeper, true dark grays and blacks. The built-in "Firefox Alpenglow" theme was also updated with a new gradient of purple, pink, and orange tones to complement the floating tab geometry.

Streamlined New Tab Page

The default New Tab page saw minor spatial adjustments to align with the rest of the Proton aesthetics. The customization menu for the New Tab page was moved from a tiny gear icon into a slide-out panel on the right side of the screen. This panel allowed users to toggle shortcuts, recommended stories, and background wallpapers using modern toggle switches rather than traditional checkboxes.