Grammar

The rules — how the vocabulary holds together. Read once, in order; you arrive holding a question.

Start with Orientation — the cascade laid out as the folder it is, each layer pointing back to the rule that governs it. Then the principles, each one idea:

Is vs for — the single cut the whole architecture rests on.
Earn its place — a layer is worth keeping only when it adds meaning the one below it lacks.
The element/block joint — a block is an element with proprietary parts; an element stands alone.
Package vs presentation — what ships, and what merely spends it.
Admitted, not assumed — borrowed code gets the last word in its own scope, never the foundation's.

One distinction carries most of it: some names mark what a thing is (blue-600), others what it's for (accent). Keep those on separate layers, keep the layers honest, and the rest falls out.