- CSS2 Spec - the official CSS 2.1 spec from the w3c
- Default Stylesheet for HTML4 - W3C suggestion for default styles
- CSS Snapshot 2010 - The current state of CSS (all versions)
- CSS Compatibility and Internet Explorer - Compatibility tables for Internet Explorer
- MDN Beginner CSS Tutorial - An excellent way to start learning CSS
- Opera Web Standards Curriculum - A great resource for web standards education
- HTMLDog - HTML and CSS tutorials... and stuff
- Equal-height Columns - Technique that separates container from content, and achieves equal height columns
- Float Tutorial - Very in-depth, step-by-step tutorial on
float - CSS Design Patterns - Excellent website on common CSS techniques
- HasLayout - Bugs and other issues in Internet Explorer
- IDs are bad - Reasons why you shouldn't use IDs in your CSS selectors
- CSS Tricks - A great blog with all sorts of useful CSS articles
- Stubbornella - Nicloe Sullivan, the progenitor of OOCSS, and all-around CSS guru
- CSS
vertical-alignproperty - How the CSS propertyvertical-alignactually works
- Demo - Clearing floats - How to clear floats, several different techniques
- Demo - Clearing columns - How to clear columns, using overflow: hidden
- MDN CSS3 Demos - Crazy stuff
- w3fools - An admonishment of w3schools, as well as a list of errors in their documentation
take a look if this fits into your list http://www.cssdesignpatterns.com/