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Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →Firefox Nova is Mozilla’s internal name for the design refresh released with Firefox 157. It is a redesign of Firefox—not a separate browser or a Firefox Labs experiment. Mozilla announced the rollout across desktop and mobile on September 29, 2026. You can customize several parts of the experience, including tab orientation, density, themes, and layout, though Mozilla has not promised a control for every visual detail.
What is Firefox Nova?
Nova is the name Mozilla used for its 2026 refresh of Firefox’s design system. Mozilla described the project as a renewal of the existing browser, not a replacement. The released interface was presented as Firefox and rolled out with Firefox 157. Mozilla’s design overview explains the project, while its launch announcement describes the release.
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The refresh changes the browser’s visual language: tabs have a softer shape, components are more rounded and consistent, and icons, spacing, and colors have been updated. Mozilla says the design foundation spans browser areas such as tabs, toolbars, the New Tab page, and Private Browsing. These are coordinated visual changes, not a new browser mode.
Which parts of Firefox can you customize?
Mozilla’s documented customization choices focus on how much space the browser uses, how tabs are arranged, and how the interface looks. They are settings to combine according to your preferences, rather than competing versions of Firefox.
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| Choice | What it changes | Useful when |
|---|---|---|
| Compact Mode | Reduces the size of tabs and the toolbar; an auto-compact option is available for smaller screens. | You want more screen space for web pages. |
| Horizontal or vertical tabs | Changes tab orientation and browser layout. | You prefer the familiar row of tabs or want tabs arranged vertically. |
| Themes and wallpapers | Changes the interface’s visual appearance; display can vary with layout and sidebar state. | You want to personalize the browser’s colors or imagery. |
| Extensions | Adds optional software features, including tools for productivity, privacy, creativity, or entertainment. | You want capabilities beyond appearance and layout. |
Mozilla describes these choices in its Firefox redesign announcement and on Firefox’s customization overview. Its announcement describes Compact Mode as a way to give more of the screen to the web, with automatic compacting for smaller screens.
Choose a denser or roomier layout
Compact Mode makes tabs and the toolbar smaller. Choose it if browser controls take up too much room; use the standard density if you prefer larger controls. The auto-compact option is intended for smaller screens. Mozilla’s announcement documents the behavior, but the available sources do not establish one universal Settings path for every platform or release.
Arrange tabs horizontally or vertically
Firefox offers classic horizontal tabs as well as vertical tabs. This lets you choose the arrangement that suits your workflow without treating the two orientations as separate products. Because changing orientation can also affect the surrounding layout, check how your chosen theme looks after switching.
Change the appearance with themes
Themes and wallpapers provide visual customization. Mozilla says themes continue to load under Nova and that most color and image properties work as before. That does not guarantee an identical appearance: changes to toolbar and sidebar geometry, especially with vertical tabs, can shift where theme colors and images appear.
Add features with extensions
Extensions are optional add-ons that provide software features; they are distinct from themes, which change appearance. Firefox’s customization page describes add-ons for areas such as productivity, privacy, creativity, and entertainment.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Will your existing Firefox theme still work?
Mozilla says existing themes continue to load, and most of their color and image properties remain compatible. A theme can nevertheless look different after the redesign because its colors and images are displayed within updated browser surfaces and layouts. For a fair check, view it with horizontal and vertical tabs, with the sidebar open and closed, and with Compact Mode enabled if you use it. Mozilla Add-ons Community Blog explains the compatibility details in its Nova theme guidance.
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. Mozilla describes Proton as a normal theme users can switch to. That is not the same as a guaranteed control to roll back the entire interface, so treat it as a way to change the theme rather than restore every previous design detail.
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Is Nova part of Firefox Labs?
No. Nova is the released design refresh associated with Firefox 157. Firefox Labs is a Settings area for experimental features that are still in development; Mozilla says experiments there are updated regularly and may be added or removed. The two refer to different things: Nova is the browser’s released design, while Labs is where users can try available experiments. See Mozilla Support’s Firefox Labs guide for how that area works.
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