If that's an example of a well coded page, I'm crying. It may not use tables but the code is still a nightmare and suffers a good case of divitis.
What you need to do is to understand your CSS well and your HTML even better and use semantic markup.
As for tutorials or reference sites... Try the big articles sites such as AListApart for CSS or HTML.
WordPress specific... I'm sure that someone will suggest some... I normally take the WP codex as reference but that will not help with HTML or CSS.
You can also find good books (SP has a few good ones too)