Reproduction for tailwindlabs/tailwindcss#19964
A CSS file imported via JS that only uses @variant is silently skipped by @tailwindcss/vite because @variant is not in the feature detection check.
pnpm install
pnpm devOpen the page with .dark class on <html>. The background should be --color-neutral-950 (very dark) but stays white because overrides.css was never processed by Tailwind.