Stylus is a versatile userstyles manager for Firefox that allows users to redesign their favorite websites effortlessly. This free extension is community-driven and offers a wide range of features, including the ability to install custom themes from various online repositories or create and manage personalized CSS stylesheets. Users can easily back up their entire database of installed styles, ensuring that their customizations are safe and can be restored if needed. With an intuitive and configurable UI, Stylus also allows users to enjoy a highly customizable experience through theming options, layout choices, and icon color tweaks.

The extension also includes two optional code validators with user-configurable rules, enhancing the development experience. Stylus operates with a focus on privacy, collecting no user data and requiring only essential permissions to function effectively. Although it does not apply styles to the Firefox UI directly due to WebExtension API limitations, it remains an essential tool for users looking to enhance their browsing experience with personalized styles.