Function scan_theme_blocks 

pub fn scan_theme_blocks(source: &str) -> ThemeScan

Scan a CSS source for Tailwind v4 @theme blocks, returning the defined design tokens plus the custom properties read via var() inside those blocks.

Tailwind v4 is CSS-first, so @theme { --color-brand: #f00; } is the unit of a user-authored design token. lightningcss treats @theme as an unknown at-rule and skips it, so this is a separate brace-matching pass (comments and strings masked first so braces / semicolons inside them never break the block boundary). Only top-level --ident: value declarations are tokens; declarations inside a nested block (e.g. @keyframes for --animate-*) are not.