It’s for people who want to understand why, when and how to use the latest HTML5 and CSS3 technologies in their everyday work.
This is another "must have" on any designer's bookshelf: Typography Book – Just My Type
The CSS3 Anthology: Take Your Sites to New Heights
Redesign The Web | Design Resources
A Practical Guide to Designing for the Web | Design Resources
HTML & CSS: Design and Build Web Sites | Design Resources