Stylem

A UserCSS-compatible user style manager for Pale Moon and other Mozilla-based software. Install, write, and manage styles that change the appearance of web pages and applications.

Features

• Style editor - syntax highlighting, error checking, preview, applies-to rule editor, and CSS namespace/image utilities
• UserCSS support - metadata parsing, variable rendering, and install flows for .user.css files
• URL matching - reference for @-moz-document rules (domain, URL, URL prefix, regexp)
• Advanced techniques - overwriting page styles, !important and specificity, AGENT_SHEET, replacing images, element selectors, DOM Inspector tool
• Install from userstyles.world or any raw .user.css URL
• Import/export styles to/from a JSON backup file
• Per-style and bulk update checking from about:addons

Quick start

1. Install Stylem from the Pale Moon Add-Ons Site.
2. Click the Stylem toolbar button to view your installed styles.
3. Select Write new style to create one.
4. Browse for styles at userstyles.world.

See the getting-started guide for more detail.

Installing from XPI

Download the latest .xpi from the Releases page and drag it into the browser. Ensure Stylish is disabled or removed first - Stylem will pick up any existing styles automatically.

Building

git clone https://github.com/Lootyhoof/stylem
cd stylem
./build.sh          # produces stylem-dev-pm.xpi
./build.sh 42       # produces stylem-42-pm.xpi

The script zips the contents of src/ into an .xpi file.

Contributing

Pull requests are welcome. Translations can be submitted via pull request - see the existing locale files under src/locale/ as a template.

License

Copyright (C) 2005–2014 Jason Barnabe <jason.barnabe@gmail.com>
Copyright (C) 2018–2026 Stylem Contributors

GPLv3 - see COPYING for the full text.