CSS: Unavoidable Bad Parts (opens in new tab)

An ersatz CSS tutorial for people who need to style a web page, but aren't web developers. I am a wrong person to write this kind of thing, as I have neither the time, nor experience. I'd much rather read a book about this. Alas, I had to learn all this stuff from trawling MDN, so perhaps it is valuable to document what I have so far.