One of the most popular alternatives to Stylus is Dark Reader, which is free and open source. Other popular alternatives are Stylebot, FireMonkey, xStyle and Amino: Live CSS Editor. You can choose from more than 10 User Styles Managers like Stylus for the web, Mac, Windows, Linux and iPhone.
This eye-care extension enables night mode creating dark themes for websites on the fly. Dark Reader inverts bright colors making them high contrast and easy to read at night.
Russia
Change the appearance of websites instantly by applying a easy to use interface for changing the CSS. Preview and install styles created by users for your favorite websites.
United States
Firemonkey is a totally new combined user-Scripts and user-Style manager. While it has similar functions to other user-Script managers like GreaseMonkey/Tampermonkey/Violentmonkey, and user-CSS managers like Stylish/Stylus/xStyle, there are also differences.
Make visual changes to any website with CSS and see changes in real time. Sync, edit, and export your custom style sheets.
A user style manager for Pale Moon, Basilisk, Interlink, SeaMonkey, and other Mozilla-based software. Install styles from userstyles.org to change how web pages and the application look.
Introducing Cascadea, the first custom style manager designed as a Safari App Extension and native macOS app. Cascadea makes it easy to install custom styles that change the look and feel of any website you want.
Dynamically load stylesheets in Firefox from plaintext files in your profile.
superUserContent is a simple Firefox plugin that creates a new directory in your profile's chrome directory called userContent.css.d. You can use this directory as a runtime path for css styleshee.
Makeover lets you change the appearance and behavior of web pages with CSS and JavaScript. To use it, you go to a web page you want to customize, tap the Makeover icon, and paste the code into the text field.
Userscript's and userstyle's — simple extension to inject own JavaScript or CSS rules to any page.
