Stylish is a user styles manager available both as an add-on for Firefox and extension for Chrome. You can manipulate, add, remove, modify user styles with just a few clicks of the mouse, without any coding knowledge whatsoever. Together with its companion website, www.userstyles.org, which hosts thousands of Stylish-compatible scripts created by the user community, Stylish can altogether change your browsing experience and take it to a new level.
The above screenshot shows a styled Google Reader page. You can browse the huge library at userstyles,org for more user styles. With Stylish installed, every user style’s page will offer a green installation button – hit that, and the next time you visit that website for which you got the style, it will appear in a totally different light.