Cscading Style Sheets (CSS) along with JavaScript manipulating the DOM is what helps make all those cool client-side effects. I'll be adding more links here soon, but for now this is a good start.
- sizzle.js (Sizzle JavaScript Selector Library)
- SitePoint.com CSS Reference
- CSS Positioning Properties At-A-Glance Guide [CSS Tutorials]
- 7 Principles Of Clean And Optimized CSS Code
- QuirksMode (A greate site for browser compatibility issues CSS and JavaScript)
- Still don't think CSS can help you? Check these two crazy sites:
- Acid Tests
- Preparing for IE 8
- 50 Really Useful CSS Tools (Thanks codeproject.com for putting this in your newsletter)