Firefox Css Theme

Name: Firefox Css Theme
Author: easonwong-de

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

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

Install

Overview

Description from the maker (original English)

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

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Developer tools

Install

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

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
The registry lists no key to fill in.

You need

npmNode.js installed (for the npx command)

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

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

Run this in your terminal

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

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

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

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

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

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

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

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 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account easonwong-de, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– 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

Compared with others in Developer toolsi

More stars than 0% of the other 1393 servers in this category
Published to the registry more recently than 77% of the other 1393 servers in this category
Basic checks equal to or better than 100% of the other 1393 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 1 of 1 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 –, and the latest version (0.3.5) reached the registry 13 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: GitHub, Desktop Commander, Cloudflare MCP

Alternatives

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

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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

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

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

Compared with others in Developer toolsi

Common questions

Alternatives

GitHub

Desktop Commander

Cloudflare MCP

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`