That's really important for user to understand CSS application order in the cases when class/id/setStyle styles contradict with each other. Referring to general CSS doc is not the best approach as it is too abstract and not helpful.

Here is a fragment:

"In ascending order of precedence:
user agent declarations
user normal declarations
author normal declarations
author important declarations
user important declarations"

I believe short table of precedence with short examples would be really helpful.