I know like 10-15 different languages, and CSS is by far the hardest to read and understand. It's easier to understand x86 assembly than CSS. CSS is basically pre-tokenized input that drives a renderer, but they sort of went halfway and didn't really make it real tokens or really human-writable.
I'd say that it should take the place of ASN.1 in the RFCs as an example of "what not to do."
CSS is hard to know, even if you know 15 languages.
I can understand many programming languages and write in a subset of many of their features, but I wouldn't claim to know them. That would require a monumental amount of day to day effort, in my opinion (see https://en.wikipedia.org/wiki/Illusion_of_explanatory_depth).
To me, the best way to understand CSS is to evaluate it after rendering, and I have been writing it for decades.
There's no use comparing CSS and assembly. It betrays a shallow understanding of CSS. Points to ponder:
- Assembly is superlatively imperative while CSS is the opposite. The difference can be jarring for some. It's commonly felt in day-to-day frontend work that switching to CSS (declarative) from almost anything else (imperative) -- JavaScript, PHP, etc. -- requires a significant mental shift, though it does get easier with experience.
- Lot of the vocabulary and concepts used in CSS come from outside the computing world, namely design and publishing. It's somehow a rarely shared factoid, but it's a hint at how too far away from Kansas we are to be making fair comparisons.
- A pervasive mistake that coders make (and unfortunately a lot of CSS teaching material out there too) is to approach CSS as a set of explicit, atomic instructions -- a fair coder-y assumption, but a bad mental model that leads to frustration. Understand that these instructions can affect one another; some switch entire layout algorithms[0] in a given scope, changing how other instructions behave (predictably).
[0] https://www.joshwcomeau.com/css/understanding-layout-algorit...