If you're a total beginner, the Head First HTML is pretty good. I know some people don't like the style of these books, but for HTML & CSS, I think it worked well.

http://www.amazon.com/Head-First-HTML-CSS-XHTML/dp/059610197...

It's very much paced towards a beginner, but I know a lot of people who love the head first HTML book: http://www.amazon.com/Head-First-HTML-CSS-XHTML/dp/059610197...

If you're more advanced or just looking for a brush up i second Dan Cederholm's book aimdave recommended.

My development and design are being outsourced. While that is taking place I am learning HTML and CSS so that I can understand certain things and tweak design.

I'm reading the Head First book on html and CSS. I didn't know anything before I started. It isn't hard to pick up. http://www.oreilly.com/catalog/hfhtmlcss/index.html