Seems like a great idea.
However, for me, never having modified css, anywhere, this documentation is almost minimal.
#1 and #2 are simple enough. Same with section #3 somewhat. Fortunately, I do already know something about Menus.
(Seems I too often have problems when someone says anything like "Now all you have to do is ... "
However, section #4 definitely need 2-3 times more clarification for this newbie. Way too much vagueness.