Many frameworks seek to abstract away from HTML (custom tags, JSFs component system) in an effort to make dealing with that particular kettle of fish easier.
Is there an
I believe the common errors beginners have with CSS are to do with specificity. If you're styling the a tag, are you sure you really want to be styling every single one in the document or a certain "class" of a tags?
I usually start out being very specific with my CSS selectors and generalize them when I see fit.
Here's a humerours article on the subject, but also informational: Specificity Wars