Using create-t3-app.

src/client/tailwind.config.cjs

@@ -0,0 +1,10 @@
+/** @type {import('tailwindcss').Config} */
+const config = {
+  content: ["./src/**/*.{js,ts,jsx,tsx}"],
+  theme: {
+    extend: {},
+  },
+  plugins: [],
+};
+
+module.exports = config;