After rewriting globals.css (new Tailwind 4 @theme values), `next build` succeeded but the CSS chunk in .next/static still contained the old theme variables. Next 16 enables turbopackFileSystemCacheForBuild by default (.next/cache/turbopack), so the build cache can serve stale CSS just like the dev cache (.next/dev). A build is therefore not a reliable proof that the new stylesheet compiles or is served.