Moving User Styles (Themes) from Stylish 3.x to Stylus

Stylish 3.1.2 and greater - Add-on Support - Mozilla Discourse

Nocturnal Firefox Theme (Read Description)

Beginner Guide to User Styles for Firefox

Melbourne (Firefox CSS, FF 29 and above) by noha-ra on DeviantArt

Stylish appears to have been removed from the Google Chrome store : r/ firefox

Line - Minimal - Firefox Theme For Stylish by wiiija on DeviantArt

Another Dimension

GitHub - JcDenton86/stylish_firefox_android_theme: An Android theme for Google pages created using Stylish Firefox add-on.

How to Add a Custom Background to the Firefox New Tab Page

Firefox 89.0 Released with New Elegant UI Design – UbuntuHandbook