Sets up and uses NativeWind v4 (Tailwind CSS v3) in Expo React Native apps, including Expo Router. Configures tailwind.config.js, global.css, babel.config.js (jsxImportSource + nativewind/babel), metro.config.js (withNativeWind + input), and app.json (web bundler metro). Troubleshoots “className not

NativeWind v4 in Expo This is deliberately a v4 skill. On the review date, the official site labels v5 a prerelease; v5/Tailwind v4 configuration is a separate stack, not a drop in refresh of these files. Inspect the lockfile before editing and keep this skill's dependency majors explicit. Establish the configuration Read package.json and the lockfile, the actual app entry, Expo config, Babel config, Metro config, Tailwind config, and the CSS entry. Identify Expo Router versus a classic entry and account for src/app , monorepos, or a custom project root. Use references/expo setup.md for the coordinated v4 setup. The invariant is: nativewind@^4 with tailwindcss@^3.4.17 ; native peers resolved through the app's Expo SDK. nativewind/preset and content globs covering every source of complete utility strings. One CSS entry using the Tailwind v3 directives, connected to both Metro's withNativeWind input and the real application entry. nativewind/babel in Babel presets , with jsxImportSource: "nativewind" on babel preset expo . nativewind env.d.ts referencing nativewind/types , without shadowing the package/module name. Preserve unrelated Metro wrappers, Babel plugins, config plugins, and project module format. Do not replace a working app's configuration wholesale or install a second incompatible Reanimated/Worklets stack. Debug in a useful order 1. Verify resolved dependency majors and the first actual error; a cache reset does not repair a Tailwind v4/v3 mismatch. 2. Compile the CSS entry with the project's installed Tailwind v3 CLI. Check content globs, static class strings, and the NativeWind preset. 3. Verify the CSS file, Metro input, and application import refer to the same file. Calculate paths from their real locations, including src/app/ layout.tsx . 4. Merge the required Babel/Metro integration, then restart Metro with npx expo start clear . 5. Test an obvious layout/text/colour change on each target platform, then the failing component. A successful web render alone does not prove native interop. Use references/troubleshooting.md for further diagnosis. Resolve bundled reference paths from this skill's directory, not the app's directory. Build components Use literal variant maps rather than dynamically constructing class names the scanner cannot see. references/patterns.md covers typed components, explicit override semantics, and accessible Pressable content. Concatenating class strings does not guarantee that the last conflicting utility wins. Use references/third party components.md only when a component needs remapProps or cssInterop ; configure interop once, not during every render. Use references/theming dark mode.md for the v4 colour scheme and CSS variable APIs. Inspect the existing safe area provider before adding another. Expo Router normally supplies the root integration; separate native roots or modal boundaries may need their own provider. Verify actual insets, nested navigation, and rotation rather than treating provider count as a universal rule. Verify and report Run the project's typecheck and Expo dependency checks, compile/bundle its actual targets, and inspect native/web rendering where those environments are available. Check dark mode, disabled/pressed states, font scaling, safe areas, and third party components affected by the change. Report the resolved dependency versions, files changed, and platforms actually tested; static configuration inspection is not a device test. Sources Reviewed 2026 09 13 against [NativeWind installation](https://www.nativewind.dev/docs/getting started/installation) and [custom components](https://www.nativewind.dev/docs/guides/custom components). For optional conflict merging, [tailwind merge](https://github.com/dcastil/tailwind merge) explicitly directs Tailwind v3 users to its v2.6.0 line.

styling-nativewind-v4-expo