"Most Firefox users are familiar with the Greasemonkey extension, a powerful tool that lets you enhance your browsing experience by rewriting HTML pages and JavaScript on the client side. The Stylish extension gives you that same level of control over Cascading Style Sheets (CSS). Unlike JavaScript, altering a page's CSS cannot change its functionality--but it can greatly enrich its usability.
"Stylish builds on Firefox's User Styles feature, which lets you override the CSS rules of any or all pages you visit. You can manually add CSS rules to Firefox's userContent.css file, including assigning specific rules to URLs that match a given pattern. Stylish provides you with a simple point-and-click way to do the same thing, and a nice interface with which to keep track of the styles you have selected..."
