[audience_mem]

Some might consider this radical, but if one considers how long CSS will be around, and intends to live in the web development world, it certainly would pay off. There's nothing like the feeling of true understanding.

Not the kind of reading material most people would turn to, admittedly. I've recently found this:

http://book.mixu.net/css/

It feels like a good balance between quotes straight from the spec, and explanation from the author.