Idk what gp meant, but css lacks what could be called “selector accounting”. You never know which parts affect what and whether they affect anything at all. Because instead of importing/use-ing styles or classes, it imposes styles over some unpredictable set of nodes through a selector. On top of that, every name is global.

This contrasts to every modern language, regardless of declarative or not, where to get the effect you import it explicitly into a chunk/block/component/etc.

If css was C, it could add “unsigned” to every first int variable in a function that goes after a typedef. Which was part of “aspect oriented programming”, which was deemed an absurdly bad practice, to put it simply.

Most of CSS is indeed statically typed (property have statically typed valid values). It's not true anymore when you introduce custom properties and IACVT though.

Custom properties can also be typed https://developer.mozilla.org/en-US/docs/Web/CSS/@property