What Is FirefoxCSS-Store?

Updated

FirefoxCSS-Store is a community hub for discovering and sharing Firefox userChrome.css themes. It collects themes contributed by the Firefox community in one browsable place, so you can find a look you like and then install it yourself. It's useful if you already know you want to customize Firefox's interface and don't want to hunt through scattered GitHub repositories and forum posts.

What you'll find there

The site presents a catalog of themes rather than a single product. Its own description reports:

  • 128 themes in the collection
  • 258 tags used to categorize them
  • 43,611 stars across the theme repositories it links to

Each theme entry points to the theme's source repository, where the actual CSS files and installation instructions live. FirefoxCSS-Store is the discovery layer; the repositories are where the code is maintained.

How the catalog is organized

Themes are tagged with descriptive keywords so you can filter by style or feature. Tags in the catalog include things like:

  • Visual style — glassmorphic, minimal, neon, retro, skeuomorphic, brutalist, catppuccin, gruvbox, dracula
  • Layout behavior — vertical-tabs, sidebar, one-line, compact, auto-hide, tabs on bottom
  • Platform cues — macos, windows11, gnome, opera, arc
  • Technical scope — userchrome, javascript, layout-only, theme

Named themes in the catalog include Firefox-Σigma, LIQUID GLASS, LUXE, Fully Transparent Theme, and Classic Theme 2011, among others.

Sorting and search

You can search the catalog and sort results by:

  • Latest shared — newest additions to the store
  • Recently updated — themes with recent changes
  • Most starred — ranked by stars on the linked repositories
  • Name — alphabetical

Sorting by "most starred" is a reasonable starting point if you want a theme with an active audience, while "recently updated" helps if you're on a current Firefox version and want something more likely to still work.

Submitting a theme

The store includes a Submit a theme option, so if you've built or found a userChrome.css theme worth sharing, you can add it to the catalog. This is what makes it a community hub rather than a fixed list.

What to keep in mind

FirefoxCSS-Store is a directory, not an installer. To actually use a theme you'll need to:

  1. Open the theme's entry and follow its link to the source repository.
  2. Read that repository's installation instructions — they vary by theme.
  3. Enable the required Firefox customization settings yourself, since userChrome.css themes generally need a specific config flag turned on.

Because themes depend on Firefox's internal UI structure, a theme that hasn't been updated in a long time may break after a Firefox release. Check the "recently updated" sort and the repository's recent activity before committing to one.