Reads a CSS custom property's computed value. Returns the trimmed value, or
fallback when the property is empty / unset / there's no DOM (SSR, worker).
undefined from a resolver leaf means "leave the base theme's value" — so a
missing var never blanks a colour.
Reads a CSS custom property's computed value. Returns the trimmed value, or
fallbackwhen the property is empty / unset / there's no DOM (SSR, worker).undefinedfrom a resolver leaf means "leave the base theme's value" — so a missing var never blanks a colour.