The article seems to focus on what is and isn't good to read. I'd say, don't focus on reading at all, focus on building. Decide to build something that'll need some CSS, and search and read and try things in pursuit of the goal of getting that thing working right. It's more interesting and easier to remember things that you've actually used, or at least tried and decided not to use, than to just read about 50 things that you might never use at all.