Stylem - 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.

CSS Next - Use tomorrow’s CSS syntax, today.

Wikiwand - A beautiful new interface to Wikipedia

Garden (Clojure) - Unlike the mini-languages that are other pre/post-processor options, Garden leverages the full power of the Clojure programming language for CSS.

FreeStylerWs - Styles and skins for all popular sites in the web

Stylus - EXPRESSIVE, DYNAMIC, ROBUST CSS