I'd recommend CSS Mastery. While a lot of the browser hacks are completely outdated, the sections on CSS fundamentals helped me a lot. It was the first time I

I'd recommend CSS Mastery. While a lot of the browser hacks are completely outdated, the sections on CSS fundamentals helped me a lot. It was the first time I went through an explanation of CSS layout and positioning and felt comfortable turning something on paper into a UI on screen that looked exactly how I wanted it to look. Before the book I relied heavily on trial and error. Now I can look at something, write some markup and CSS, and it does exactly what I want.