Firefox Css Theme

Name: Firefox Css Theme
Author: easonwong-de

by easonwong-deversion 0.3.5i★ 4iRuns on your computer

Registry nameio.github.easonwong-de/firefox-css-theme

How to install

What it does

MCP for building, inspecting, and live-debugging Firefox CSS themes.

Connects Runs on your computer
Account or key No key needed
Category Developer tools

Install

Pick the AI app you use, then copy the settings.

Passed 3/3 checks · Runs on your computer · ✓ Commands checked Nov 13, 2026

First: which AI do you use?

ClaudeWeb · app · phoneChatGPTWebClaude CodeTerminalCursorCode editorVS CodeCode editorOtherOther apps

Pick your app and the steps appear below.

Works with Claude, with some setup first

Install Node.js on your computer first (one time) · Only the Claude desktop app (Windows or Mac), not the web or phone

Install Node.js
One time only; it works for every server that needs Node.js
Open the Node.js download page ↗
Done
Open the Claude desktop app’s settings file
SettingsDeveloperEdit Config
Done

Paste these settings and save the file

{
  "mcpServers": {
    "firefox-css-theme": {
      "command": "npx",
      "args": [
        "-y",
        "firefox-css-theme",
        "mcp"
      ]
    }
  }
}

Done

Quit Claude and open it again
Done
Try it
Use Firefox Css Theme and tell me what you can do for me, then show me one thing
✓ If Claude says it is using Firefox Css Theme or shows a Firefox Css Theme tool in the answer, you are connected

Menu names checked against Anthropic’s help page on Nov 11, 2026 · your screen may differ slightly by app version

ChatGPT cannot connect Firefox Css Theme yet

Firefox Css Theme runs on your computer, but ChatGPT can only connect servers that run on the web

What you can do instead

A · Use an app that can connect Firefox Css Theme

Steps for Claude →Install Node.js on your computer first (one time) · Only the Claude desktop app (Windows or Mac), not the web or phone
Steps for Claude Code →Install Node.js on your computer first (one time)
Steps for Cursor →Install Node.js on your computer first (one time)
Steps for VS Code →Install Node.js on your computer first (one time)

B · Others in Developer tools that work with ChatGPT

Picked from the most used in the same category, only ones that connect by address with no key

Sentry✓ ChatGPT
Compiler Explorer✓ ChatGPT
GitDiagram✓ ChatGPT

Works with Claude Code, with some setup first

Install Node.js on your computer first (one time)

Install Node.js
One time only; it works for every server that needs Node.js
Open the Node.js download page ↗
Done
Open Terminal
Mac: press Command+Space and type Terminal · Windows: open PowerShell
Done

Paste this command and press Enter

claude mcp add --scope user firefox-css-theme -- npx -y firefox-css-theme mcp

Done

Type /mcp in Claude Code
You should see Firefox Css Theme listed as connected
Done
Try it
Use Firefox Css Theme and tell me what you can do for me, then show me one thing
✓ If Claude Code says it is using Firefox Css Theme or shows a Firefox Css Theme tool in the answer, you are connected

Menu names checked against Anthropic’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with Cursor, with some setup first

Install Node.js on your computer first (one time)

Install Node.js
One time only; it works for every server that needs Node.js
Open the Node.js download page ↗
Done
Click this button to open Cursor
Open in Cursor
Cursor asks you to confirm; click Install
Done
Open the AI chat in Cursor in Agent mode
Done
Try it
Use Firefox Css Theme and tell me what you can do for me, then show me one thing
✓ If Cursor says it is using Firefox Css Theme or shows a Firefox Css Theme tool in the answer, you are connected

Menu names checked against Cursor’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with VS Code, with some setup first

Install Node.js on your computer first (one time)

Install Node.js
One time only; it works for every server that needs Node.js
Open the Node.js download page ↗
Done
Click this button to open VS Code
Open in VS Code
VS Code asks you to confirm; click Install
Done
Open the AI chat in VS Code in Agent mode
Done
Try it
Use Firefox Css Theme and tell me what you can do for me, then show me one thing
✓ If VS Code says it is using Firefox Css Theme or shows a Firefox Css Theme tool in the answer, you are connected

Menu names checked against VS Code’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Other apps that use MCP, such as Windsurf, Zed or Gemini CLI, each add servers differently. See how in the app list.

See every app that uses MCP →

JSON settings are under “For developers” below

Stuck? Ask people who use Firefox Css Theme💬 Discussion →

For developers: Terminal commands and JSON settings

Installed on your computer

Claude Code

claude mcp add --scope user firefox-css-theme -- npx -y firefox-css-theme mcp

Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "firefox-css-theme": {
      "command": "npx",
      "args": [
        "-y",
        "firefox-css-theme",
        "mcp"
      ]
    }
  }
}

Cursor (~/.cursor/mcp.json)

{
  "mcpServers": {
    "firefox-css-theme": {
      "command": "npx",
      "args": [
        "-y",
        "firefox-css-theme",
        "mcp"
      ]
    }
  }
}

VS Code (mcp.json)

{
  "servers": {
    "firefox-css-theme": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "firefox-css-theme",
        "mcp"
      ]
    }
  }
}

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

At a glance

GitHub stars i: 4
Downloads per weeki: 103/wk
Licence i: MIT
Connection: Runs on your computer
Transport: stdio
Latest versioni: 0.3.5
Categoryi: Developer tools
Published to registryi: Oct 25, 2026
Code last changedi: Nov 14, 2026
Maker: easonwong-de
Packages: npm: firefox-css-theme
Repo: easonwong-de/Firefox-CSS-Theme
Registry status: Active

Which apps can use it

Based on how this server connects and on each app’s own docs, checked Nov 10, 2026.

Run on your computer in

Claude Goose LM Studio Msty Studio Cherry Studio Cursor VS Code + GitHub Copilot Visual Studio Windsurf (Devin Desktop)Zed Kiro Cline Continue JetBrains AI Assistant Claude Code Codex CLI Gemini CLI OpenCode nodecode Warp LibreChat Raycast

All apps, with pros and cons →

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 14, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account easonwong-de, which owns the repo
✓ Pass
Still maintained
Code last changed today
✓ Pass
Has a licence
Uses MIT
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Discussion

Ask, share a tip or report that it does not work. Sorted by what people marked helpful.

No posts yet. Be the first to ask or share.

Posts here are written by users, not the PopNx team.

User reviews

No reviews yet

Compared with others in Developer toolsi

More stars than 83% of the other 5886 servers in this category
Published to the registry more recently than 58% of the other 5886 servers in this category
Basic checks equal to or better than 100% of the other 5886 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Firefox Css Theme safe?

It passed 3 of 3 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed today, and the latest version (0.3.5) reached the registry 20 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Node.js on your computer.

What can I use instead?

In the same category: REA, GitHub, Serena MCP: the IDE for your agent

Others in the same category

Servers in the same category from other makers, sorted by stars.

Reading a card:↓ Downloads per weeki★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

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GitHub

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Install

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Runs on your computer

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README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

Firefox CSS Theme

A toolkit for scaffolding, live-debugging, and installing Firefox CSS themes. For agentic DOM inspection and live styling, an MCP server is also available.

Getting Started

[!TIP]

You need Node.js to get started.

For Theme Authors

Scaffold a new theme project using npx:

npx firefox-css-theme create

This interactively prompts for your theme name and stylesheet targets (userChrome only, userContent only, or both).

If you have already opened a theme repository, launch Firefox with live CSS hot-reloading:

npx firefox-css-theme start

[!NOTE]

Theme entry files (userChrome.css and/or userContent.css) must be located at the root of the project directory.

For Theme Users

Navigate to the theme directory and install the stylesheets:

npx firefox-css-theme install

The toolkit will look for userChrome.css and userContent.css in the current directory, and install them into the selected Firefox profile.

For the full list of CLI options, run npx firefox-css-theme --help.

MCP Server Usage

The MCP server enables AI assistants to inspect the Firefox chrome DOM, query computed styles, inject custom CSS, and capture UI screenshots in real time.

Configuration

Add the server to your preferred client or development environment:

Claude Code

claude mcp add firefox-css-theme -- npx -y firefox-css-theme mcp

Codex

codex mcp add firefox-css-theme -- npx -y firefox-css-theme mcp

IDE MCP Configuration

"mcpServers": { "firefox-css-theme": { "command": "npx", "args": ["-y", "firefox-css-theme", "mcp"] } } }

Available MCP Tools

launch_browser: Launches Firefox with chrome debugging.
close_browser: Terminates the browser instance.
customize_toolbar: Toggles the Firefox "Customise Toolbar" mode.
get_ui_tree: Dumps the hierarchical DOM tree of the selected UI element.
query_ui_elements: Queries elements matching a CSS selector in the browser chrome.
get_computed_styles: Extracts computed CSS property values of a specific UI element.
inject_theme_css: Injects a stylesheet into the live UI.
remove_theme_css: Removes an injected stylesheet.
list_theme_css: Lists all currently injected stylesheets.
take_ui_screenshot: Captures a screenshot of a specific UI component.
execute_chrome_javascript: Runs JavaScript in the browser chrome window context.

Commands

`firefox-css-theme create`

Scaffold a new Firefox CSS theme project.

Usage

npx firefox-css-theme create [options]

Options

Option	Description
`-n, --name`	Theme name
`-t, --target`	Stylesheet target: chrome, content, or both
`-f, --force`	Proceed without warning

`firefox-css-theme start`

Launch Firefox with live stylesheet bundling and hot-reloading.

Usage

npx firefox-css-theme start [options]

Options

Option	Description
`-b, --binary`	Path to Firefox executable
`-p, --profile`	Firefox profile name
`--headless`	Run in headless mode
`--atbc`	Start with Adaptive Tab Bar Colour
`--no-toolbox`	Disable Browser Toolbox
`--no-watch`	Disable file watching

`firefox-css-theme install`

Install compiled stylesheets from the current working directory into a Firefox profile.

Usage

npx firefox-css-theme install [options]

Options

Option	Description
`-p, --profile`	Firefox profile name
`-m, --merge`	Merge with existing stylesheets
`-f, --force`	Proceed without warning

[!WARNING]

This operation will overwrite existing CSS themes in the profile unless --merge is specified. A backup is advised.

`firefox-css-theme mcp`

Start the Model Context Protocol (MCP) server.

Usage

npx firefox-css-theme mcp [options]

Options

Option	Description
`-b, --binary`	Path to Firefox executable
`-p, --profile`	Firefox profile name

Firefox Css Theme

What it does

Install

Install Node.js

Open the Claude desktop app’s settings file

Paste these settings and save the file

Quit Claude and open it again

Try it

What you can do instead

Install Node.js

Open Terminal

Paste this command and press Enter

Type /mcp in Claude Code

Try it

Install Node.js

Click this button to open Cursor

Open the AI chat in Cursor in Agent mode

Try it

Install Node.js

Click this button to open VS Code

Open the AI chat in VS Code in Agent mode

Try it

Installed on your computer

At a glance

Which apps can use it

Related guides

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Discussion

User reviews

Compared with others in Developer toolsi

Common questions

Others in the same category

REA

GitHub

Serena MCP: the IDE for your agent

README from the maker

Firefox CSS Theme

Getting Started

For Theme Authors

For Theme Users

MCP Server Usage

Configuration

Claude Code

Codex

IDE MCP Configuration

Available MCP Tools

Commands

firefox-css-theme create

Usage

Options

firefox-css-theme start

Usage

Options

firefox-css-theme install

Usage

Options

firefox-css-theme mcp

Usage

Options

`firefox-css-theme create`

`firefox-css-theme start`

`firefox-css-theme install`

`firefox-css-theme mcp`