Higgs Boson Firefox Theme

January 24, 2026 ยท View on GitHub

A comprehensive Firefox customization project providing a highly customized browser experience with vertical tabs, custom toolbars, and extensive UI modifications.

Firefox Theme Screenshot

๐Ÿš€ Quick Start

  1. Enable userChrome CSS support:

    • Navigate to about:config
    • Set toolkit.legacyUserProfileCustomizations.stylesheets to true
  2. Install the theme:

    • Copy all files to your Firefox profile's chrome/ directory
    • Restart Firefox
  3. For JavaScript functionality (optional):

๐Ÿ“š Complete Documentation

Getting Started

Technical Documentation

Development

โœจ Key Features

  • ๐Ÿ”„ Vertical Tabs: Custom vertical tab implementation with drag-and-drop support
  • ๐Ÿ“Š Second Sidebar: Advanced sidebar system with web panels (like Vivaldi/Floorp)
  • ๐ŸŽจ Custom Toolbars: Redesigned toolbar layout framing the browser window
  • ๐ŸŒ™ Theme Support: Light/dark mode with blur effects and custom styling
  • โšก JavaScript Extensions: Enhanced functionality through UserChrome.js scripts
  • ๐Ÿ“ฑ Responsive Design: Adapts to different window sizes and screen resolutions
  • ๐Ÿ”ง Highly Customizable: Extensive configuration options via CSS variables

๐ŸŽฏ Target Use Cases

This theme is designed for users who:

  • Want a clean, efficient browser interface
  • Prefer vertical tab management for better space utilization
  • Use many browser extensions and need quick access
  • Appreciate customizable, keyboard-friendly workflows
  • Want advanced sidebar functionality with web panels

๐Ÿ—๏ธ Architecture

firefox-theme/
โ”œโ”€โ”€ userChrome.css          # Main CSS entry point
โ”œโ”€โ”€ userContent.css         # Content page styling  
โ”œโ”€โ”€ css/                    # CSS modules
โ”‚   โ”œโ”€โ”€ chrome/            # Browser UI styling
โ”‚   โ”œโ”€โ”€ common/            # Shared variables and utilities
โ”‚   โ””โ”€โ”€ content/           # Web content styling
โ”œโ”€โ”€ JS/                     # JavaScript modules
โ”‚   โ”œโ”€โ”€ second_sidebar/    # Advanced sidebar system
โ”‚   โ””โ”€โ”€ *.uc.js           # UserChrome.js scripts
โ”œโ”€โ”€ resources/             # Assets and configurations
โ””โ”€โ”€ .github/documentation/ # Comprehensive documentation

๐Ÿ”ง System Requirements

  • Firefox: Version 100+ (tested with latest stable, ESR, Beta, and Nightly)
  • Operating Systems: Windows 10/11, macOS 10.15+, Linux (most distributions)
  • Optional: fx-autoconfig for JavaScript functionality

โš ๏ธ Installation Notes

NixOS Users: This configuration integrates with NixOS declarative configurations. See the "imperative" branch for non-declarative installation methods.

JavaScript Features: The second sidebar and advanced features require fx-autoconfig script loader. The theme works with CSS-only installation but with reduced functionality.

๐Ÿค Contributing

We welcome contributions! Please see our Development Guide for:

  • Setting up a development environment
  • Code style guidelines and best practices
  • Testing procedures
  • Pull request process

๐Ÿ“„ License

This project is released under the Mozilla Public License.

๐Ÿ™ Acknowledgments

  • fx-autoconfig - Script loading framework
  • aminomancer - Comprehensive userChrome.js documentation
  • MrOtherGuy - Firefox CSS resources and tools
  • Firefox userChrome.css community - Inspiration and code examples

Need help? Check our troubleshooting guide or browse the complete documentation.