CSS Resources
CSS W3 SchoolsA very useful site full of interactive tutorials from basic to advanced CSS tips and tricks including CSS Syntax, CSS How To, CSS Background, formatting and styling text in CSS, CSS Border, CSS Outline, CSS Margin, CSS Padding, CSS List, CSS Table, CSS Positioning, CSS Image Opacity, and CSS Examples.
CSS Zen Garden
A demonstration of what can be accomplished visually through CSS-based design.
How to Use CSS for Search Engine Optimization
Using external CSS files to determine the design attributes creates clean HTML code and will create better search engine rankings. With some knowledge of CSS you can change the code without destroying the visual layout.
A List Apart
Web design, content, and coding. Accessibility, CSS, XHTML, scripting, server side, front and back end. Designing with web standards.