Fixes#1463We'll have to bail in some cases that we didn't before to fix this. Thisseems fine though. The core problem was that given this theme:```css@theme {  --radius: calc(var(--radius));}```We'd see this CSS:```css.rounded {  border-radius: calc(var(--radius));}```And we'd try to replace variables in `calc(var(--radius))`. This doesn't_start_ with a var(…) so our recursion guards didn't catch this.This entire system is a bit fragile and I'll be working to clean this upalong with how we handle pixel equivalents, light-dark replacements,color-mix replacements, etc… in some future PRs (#1330 is one of thosebut I want to reorganize + tweak some code first in an earlier PR whichwill make that one "nicer")