HTML and CSS are rather easy to learn; I'm not sure that you'd need a book just to learn the fundamental concepts/syntax of either. If what you're looking for is more of a "how-to" than help with design techniques, HTML Dog is a great resource for learning HTML and CSS. It pretty much walks you through the whole process of producing valid and semantically correct code.
If you're going to be working with JavaScript, then I really suggest you pick up DOM Scripting by Jeremy Keith. JS isn't an essential part of web design, but it often comes into play if you're trying to add some behavior functionality to your design. DOM Scripting is a really easy read and pretty easy to follow. It's not the all-knowing reference book, but once you learn the concepts from the book, you can apply them to the new things you learn in the "real world."
-Chasen