How to Submit Your Own userChrome.css Theme to FirefoxCSS-Store

FirefoxCSS-Store is a community hub that aggregates userChrome.css themes, and its homepage includes a Submit a theme entry point alongside the theme gallery. The site itself does not publish a detailed submission checklist in the available page content, so the practical path is: prepare a public repository or hosted CSS file for your theme, then use the site's submission option to share it with the community. If your theme is already on GitHub, that is the most natural format, since the store's listings link out to theme repositories (for example, the Pro-Fox theme links to its GitHub repository).

What the Store Expects From a Theme

The homepage shows the scale and shape of the collection: 128 themes, 258 tags, and 43,611 stars across theme repos. That tells you what a successful submission looks like in practice — a theme that can be described with a name, a set of tags, and a link to a repository where the CSS lives.

Step-by-Step: Preparing and Submitting

1. Package your theme in a public place

Put your userChrome.css (and any supporting files such as userContent.css, images, or a chrome/ folder structure) in a public repository. GitHub is the common choice because the store's existing listings link to GitHub repos. Include a README that states:

• What the theme does and which Firefox versions it targets
• Installation steps (where to place the chrome folder, the toolkit.legacyUserProfileCustomizations.stylesheets preference)
• Any dependencies, like the Sidebery or Tree Style Tab extensions for sidebar-based themes

2. Choose accurate tags

The store's tag list is the search surface users actually browse. Pick tags that already exist where they fit — dark, minimal, transparent, vertical-tabs, one-line, glassmorphic, rounded, compact — rather than inventing near-duplicates. A theme tagged minimal and dark is findable; one tagged mycooldarkmode is not.

3. Use the "Submit a theme" option

On the homepage, next to the search and sort controls, there is a Submit a theme link. That is the intended entry point for adding your work. Follow whatever form or instructions it presents, supplying your theme name, description, tags, and the repository URL.

4. Expect a community listing, not an instant publish

The store describes itself as a community hub for discovering and sharing themes, and the gallery is sorted by "Latest shared", "Recently updated", and "Most starred". That sorting implies submissions are collected and surfaced as listings rather than being a live self-publish feed. The available page content does not specify a review process, so treat the timing and any editorial checks as unspecified rather than guaranteed.

Common Pitfalls

• Broken install instructions. If your README omits the about:config preference or the profile-folder path, users will install the CSS and see nothing change.
• Missing source link. A theme with no public repo cannot be verified or updated, and the store's own listings consistently link to repositories.
• Tag mismatch. Tagging a light theme dark or a layout-only theme colorscheme makes it show up in the wrong searches.
• No version notes. Firefox's UI changes between releases; state which versions you tested so users know whether a broken layout is your theme or their browser.

Quick Checklist Before Submitting

• [ ] userChrome.css in a public repo with a README
• [ ] Installation steps including the toolkit.legacyUserProfileCustomizations.stylesheets preference
• [ ] A short name and 1–2 sentence description
• [ ] 3–8 tags drawn from the store's existing vocabulary
• [ ] Tested on a stated Firefox version
• [ ] Submission made through the homepage's Submit a theme link