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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Firefox Nova is Mozilla’s internal name for the design refresh released with Firefox 157. It is not a separate browser or a Firefox Labs experiment. The redesign updates the look of tabs, toolbars, icons, spacing, colors and other browser surfaces; you can personalize it with options such as Compact Mode, horizontal or vertical tabs, and themes.
What Firefox Nova means
Mozilla used “Nova” as the internal name for a refresh of Firefox’s design system. The company announced the rollout on September 29, 2026, as part of Firefox 157 for desktop and mobile. The name describes the redesign, not a separate browser or a special mode you need to install. Mozilla’s design announcement explains the name as a renewal built from existing elements.
The update gives tabs a softer shape and brings more rounded, consistent components, refreshed icons and spacing, and a warmer palette. Mozilla says the shared design foundation spans areas such as tabs, toolbars, the New Tab page and Private Browsing. These are changes to Firefox’s interface, rather than changes to the websites you visit.
Which parts of Firefox can you customize?
Nova’s visual refresh does not remove Firefox’s documented appearance and layout choices. The main decisions are how much screen space the browser controls use, how tabs are arranged, and which colors or imagery appear in the interface.
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| Choice | What it changes | Useful when |
|---|---|---|
| Standard or Compact Mode | Compact Mode reduces the size of tabs and the toolbar; Mozilla also describes an auto-compact option for smaller screens. | You want more screen area for web pages. |
| Horizontal or vertical tabs | Changes the orientation and organization of the tab strip. | You prefer a familiar top tab bar or want tabs arranged vertically. |
| Themes and wallpapers | Changes the browser’s visual appearance, including colors and imagery. | You want to personalize Firefox’s look. |
| Add-ons | Adds optional browser features, such as tools for productivity, privacy, creativity or entertainment. | You want functionality beyond appearance or layout. |
Compact Mode for more page space
Compact Mode makes tabs and the toolbar smaller, giving the web page more room. Mozilla also describes an auto-compact option for smaller screens. Compact Mode changes density; it is not a way to restore an older Firefox design.
Horizontal or vertical tabs
Firefox offers classic horizontal tabs as well as vertical tabs. This is a layout choice, so choose the arrangement that suits how you scan and manage open pages.
Themes and add-ons
Themes and wallpapers let you change Firefox’s appearance, while add-ons can provide additional software features. Mozilla’s Firefox customization overview describes themes and layout choices alongside add-ons. Add-ons are optional digital tools, not physical accessories.
Will your existing Firefox theme still work?
Mozilla says existing themes continue to load under Nova, and most color and image properties work as they did before. Their appearance can still shift because the toolbar and sidebar geometry and the vertical-tab layout change where colors and background images are displayed. A theme may therefore look different without being broken.
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If you create or rely on a particular theme, check it in the layouts you actually use: horizontal and vertical tabs, the sidebar open and closed, and Compact Mode where relevant. Mozilla’s theme compatibility post discusses these changes.
Can you switch back to the old Firefox look?
Mozilla says it featured a Firefox Proton theme in Add-ons Manager starting September 29, 2026, for people who prefer the earlier visual treatment. It is a normal theme you can switch to—not a guaranteed full interface rollback. The available information does not establish that every part of Nova’s layout or behavior can be reverted with it.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Is Nova part of Firefox Labs?
No. Nova was the name for the design refresh released with Firefox 157. Firefox Labs is a Settings area for experiments that are still in development; Mozilla says those experiments are updated regularly and may be added or removed. The Firefox Labs support page explains the experimental feature area. Do not treat the released Nova interface as a Labs feature you need to enable.
What may change over time
Firefox versions, theme behavior and Labs experiments can change. Mozilla’s May 2026 design post said it was exploring future controls for interface shapes such as tabs and components; that describes exploration, not a customization control promised as available. Check Mozilla’s Firefox updates page for current product updates.
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