Pardon me, but I've read tens of technical references, rationales and getting started's in my life, but not a single one was so ritualistic and/or useless for practicing as everything about css. The reason is...
Their knowledge of CSS is built from a set of "how do I do X in CSS" searches
Because "box model and selector specificity" is light years away from how to do X. If you want an analogy, you are suggesting to win a chess tournament by thoroughly learning chess rules and figures. But you can not. It is okay for chess, where you build up your expertise for years and decades, but not for a rapid application development. Css is a bike with no front wheel, one pedal and it only turns left, unless you know that sit-backwards hack. There are better (more reason-enabling at least) layout systems out there, but cool web guys are digging in their heels on that "css" thing. And that would be okay, iff they made that damn bike at least complete, at least once in its lifetime.
Want a simple, trivial puzzle?
(component1)
.form
label.a input
label.b input
.some-content
(component2)
.form
label.c input
Make all labels of the same,
non-fixed width, for these forms to look more aligned under different label localisations. Without recomposing layout elements. In constraint-based layout, it is a.w = b.w = c.w (priority:low). In gtk, you add (a,b,c) into the same SizeGroup. In css I'm doing it the wrong way, these requirements are strange, I should rethink my model, take a different/better approach, maybe it is okay for them to not be aligned, because awesome css at least solves a huge load of problems and the internet rests on it, bla-bla-blah.
That even may have an almost-css-only solution, but whatever it is, it will be yet another "recipe" with a pile of crutches as ingredients. Which is likely not compatible with rendering loops or a structure of a half of popular js/css frameworks.