Dan Cederholm’s book Web Standards Solutions is definitely not for beginners. He hits the ground running, right from the first chapter, jumping into full CSS syntax with tips and tricks for styling lists and headers; not much in the way of “getting started” or “style basics.”
For advanced users, it’s an excellent reference to extend existing markup knowledge in different creative and technical directions. This book recommends standards-based markup practices to achieve various results within different contexts, from simple padding and floating to Fahrner Image Replacement. Much of the content is rehashed and rearranged from the Simplequiz, which is a great way to contrast current presentational “tag soup” conventions with proper structural markup. So far it’s all been stuff that I already know and use in my day-to-day design, but I’m seeing a few things in later chapters which should pose both unique solutions to as-yet-unmet CSS design challenges.
Don’t start with this if you want a starter’s XHTML/CSS manual or a comprehensive syntax guide. If CSS isn’t like a second language to you yet, you’ll probably want to read Web Standards Solutions with a couple of cheat sheets close by. And of course, the easiest way to learn is to do: fire up a text editor and a [real] browser and hammer out that code as you read about it. The sooner you’re out of the tag soup, the better.