Tailwind CSS in Next.js : Install and Wire-up

Covers every supported combination of Tailwind version (v3.4 vs v4.0+) and Next.js router (App Router vs Pages Router), plus next/font integration and the documented Turbopack quirk.

Companion skills :

• tailwind-impl-config-v4 : v4 CSS-first config surface (@theme, @source)
• tailwind-impl-config-v3 : v3 JS config surface (tailwind.config.js)
• tailwind-impl-build-vite : same install topic for the Vite plugin
• tailwind-core-v3-vs-v4 : version-wide API differences

Decision : Which Combination Do You Have