CSS for some style. In a Big Way.

CSS Zen Garden Resource Guide

extensive top-notch css links

CSS Cheat Sheets

by Leslie Frank

by ilovejackdaniels

University of Texas: Learn CSS

A very thorough step-by-step introduction to CSS.

New York Public Library CSS Style Guide

A very nice (although now slightly dated) overview of stylesheets.

The World Wide Web Consortium (W3C): starting with HTML + CSS

An introductory tutorial by the group that created the standards for HTML and CSS.

w3schools: CSS Tutorial

From basic to advanced. Including bonus fun quizes and exams!

w3schools: CSS Examples

Play with their CSS and HTML examples on the fly — a good place to spend time

CSS: Getting Into Good Coding Habits

More advanced tips for writing good CSS and avoid some browser bugs