The Line 25 website has a nice run-down of articles from various sources entitled 15 Must Read Articles for CSS Beginners. We have covered most of the subjects at our workshop, and others will be covered next season.
Don't be fooled by "Beginners" in the title. These articles might be introductory, but some of the subjects are fairly advanced. And you might find that the locations of these articles are sites that you will want to follow for future articles.