I would recommend
CSS: The Missing Manual, D S McFarland (2009, but still very relevant)
HTML & CSS: Design and Build Web Sites, Jon Duckett (2011) - a very nice book to own, but not quite as detailed as The Missing Manual.
"I'm here to save your life. But if I'm going to do that, I'll need total uninanonynymity
." Me Myself & Irene
Validate your HTML