Stylus is a browser extension that manages and applies custom CSS themes to websites across Chrome, Firefox, and Chromium-based browsers.
The tool solves the problem of restyling websites through user-created CSS themes. It works by installing styles from external galleries like USW and USO archive, or by installing UserCSS styles with advanced customization options from any raw plain text URL. The extension includes a built-in editor supporting CSS, LESS, and Stylus syntax with linting via Stylelint and CSSLint-mod, and supports external IDE development through a live reload feature. Styles can be synced across devices via Dropbox, Google Drive, OneDrive, or WebDAV-compatible servers, and backed up to JSON files. The content script injected into web pages is lightweight at approximately 10 kilobytes and executes in about a millisecond.
Stylus is designed for users who want fine-grained control over website appearance without relying on a service that collects analytics or user data. The project explicitly positions itself as a privacy-focused alternative to the original Stylish extension, which was sold to a web analytics company. It suits anyone from casual users applying existing themes to developers writing and maintaining custom styles. The tool offers extensive configuration options for both UI behavior and style management, including per-style and global auto-update settings.
The project maintains active continuous integration with pre-release test builds available from workflow artifacts. Development activity includes regular updates across multiple platform targets, with separate release channels for stable and beta versions on official extension stores and GitHub. The codebase supports both modern Manifest V3 extensions and legacy Manifest V2 versions for older browsers, indicating ongoing maintenance for compatibility across different browser generations.
