Firefox Adaptive Sur Theme

May 14, 2026 · View on GitHub

A macOS-styled Firefox CSS theme based on Firefox WhiteSur theme with Adaptive Tab Bar Colour support.

Note: This CSS theme is optimised for the release version of Firefox on macOS. Compatibility with other platforms or Firefox versions is not guaranteed. As this theme is actively used on my primary device, graphical issues and regressions will be addressed promptly.

Installation

  1. Go to about:support in Firefox → Application Basics → Profile Folder → Open the folder.

  2. If a chrome folder does not already exist in your profile directory, create one.

  3. Clone this repository into the chrome folder.

  4. Go to about:config and enable:

    • toolkit.legacyUserProfileCustomizations.stylesheets
    • svg.context-properties.content.enabled

  5. Restart Firefox.

Theme Customisation

Configuration is done through userChrome.css and userContent.css. Available modules include:

userChrome.css

  • extension-menu-in-grid.css (enabled by default)

  • hide-single-tab.css (requires removing buttons from the tab bar)

  • mini-tabbar.css

userContent.css

  • apple-style-homepage.css
  • apple-style-twp-popup.css

Full list of modules is available in chrome/theme/customs.

Credits

This project is based on the original Firefox WhiteSur theme by AdamXweb. Additional adaptations and maintenance by easonwong-de.