For anyone who wants to have a deeper understanding of how CSS works, I highly recommend this short online book (freely available): http://book.mixu.net/css/ h

For anyone who wants to have a deeper understanding of how CSS works, I highly recommend this short online book (freely available): http://book.mixu.net/css/ http://book.mixu.net/css/ It delves deep into the underlying concepts for CSS layout as described by the spec. I think layout is the hardest part of CSS, as changes can potentially affect the whole page, so it's worth studying the fundamentals. It was written before grid was a thing, but it does cover flexbox. I do wish CSS layout was easier to understand. Perhaps CSS grid will change this as it becomes widely adopted.