| While I think this is definitely a useful foundation, things get a lot more complicated quickly once you jump into a large site's stylesheet(s). Why isn't this element the size I specified? Or why is there a tiny amount of scroll overflow here when I specify overflow-x hidden? What does vertical-align do and how does it work when inline and inline-block boxes are in an inline flow? etc. etc. So I would add that the next frontier after learning the proposed foundations is learning how the browser actually determines box sizes and layout, and I think this is difficult to understand, mainly because it jumps straight into the spec, or worse, your browser's layout engine specifics. https://www.w3.org/TR/css-sizing-3/#auto-box-sizes for instance is a nontrivial subsystem that a CSS dev will easily run into when nesting flex containers, and I think the standard box model of yore wasn't really written to help grok these concepts. Edit: one particularly hairy explanation from the spec I recently ran into while trying to deepen my understanding of the box model: "Except for table boxes, which are described in a later chapter, and replaced elements, a block-level box is also a block container box. A block container box either contains only block-level boxes or establishes an inline formatting context and thus contains only inline-level boxes. Not all block container boxes are block-level boxes: non-replaced inline blocks and non-replaced table cells are block containers but not block-level boxes. Block-level boxes that are also block containers are called block boxes." Not saying this is relevant for the average use case, but I believe even something like the box model is a day-to-learn-lifetime-to-master kind of thing. |