Tailwind CSS 4.3.1 is out: highlights and upgrade guide

What's included in Tailwind CSS 4.3.1

Details from the official release page.

Added

• Add --silent option to suppress output in @tailwindcss/cli (#20100)

Fixed

• Remove deprecation warnings by using Module#registerHooks instead of Module#register on Node 26+ (#20028)
• Canonicalization: don't crash when plugin utilities throw for unsupported values (#20052)
• Allow @apply to be used with CSS mixins (#19427)
• Ensure not-* correctly negates @container queries, including style(…) queries (#20059)
• Ensure drop-shadow-* color utilities work with custom shadow values containing calc(…) (#20080)
• Fix 'Sourcemap is likely to be incorrect' warnings when using @tailwindcss/vite (#20103)
• Ensure @tailwindcss/webpack can be installed in Rspack projects without requiring webpack as a peer dependency (#20027)
• Canonicalization: don't suggest invalid calc(…) expressions (e.g. px-[calc(1rem+0px)] → px-[calc(1rem+0)]) (#20127)
• Canonicalization: avoid suggesting large spacing-scale values for arbitrary lengths (e.g. left-[99999px] → left-[99999px], not left-24999.75) (#20130)
• Ensure @tailwindcss/cli in --watch mode recovers when a tracked dependency is deleted and restored (#20137)
• Ensure standalone @tailwindcss/cli binaries are ignored when scanning for class candidates (#20139)
• Ensure class candidates are extracted from Twig addClass(…) and removeClass(…) calls (#20198)
• Don't crash in the Ruby or Vue preprocessors when scanning files containing invalid UTF-8 bytes (#19588)
• Allow @variant to be used inside addBase (#19480)
• Ensure @source globs with symlinks are preserved (#20203)
• Ensure later @source rules can re-include files excluded by earlier @source not rules (#20203)
• Upgrade: don't migrate empty class rules to invalid @utility rules (#20205)
• Ensure transitions between inset-shadow-none and other inset shadows work correctly (#20208)
• Ensure explicitly referenced @source directories are scanned even when ignored by git (#20214)
• Ensure @source globs ending in **/* preserve dynamic path segments to avoid scanning too many files (#20217)
• Canonicalization: don't fold calc(…) divisions when the result would require high precision (e.g. w-[calc(100%/3.5)] → w-[calc(100%/3.5)], not w-[28.571428571428573%]) (#20221)
• Serve ESM type declarations to ESM importers of @tailwindcss/postcss (#20228)

Changed

• Generate 0 instead of calc(var(--spacing) * 0) for spacing utilities like m-0 and left-0 (#20196)
• Generate var(--spacing) instead of calc(var(--spacing) * 1) for spacing utilities like m-1 and left-1 (#20196)