I found this site that has a few articles for CSS beginners. As I'm an ultra beginner some of it is a little over my head but reading through some of these articles I found them informative and I'm sure as we go along it will make (more sense and) a nice reference point for the future. There are a few good ones though that talk about things we've touched on like the box model, and the way different browser interpret CSS differently, and divs.

http://line25.com/articles/15-must-read-articles-for-css-beginners