Tailwind CSS v4 with Next.js 16: CSS-First Setup, @theme Tokens, and Design System Migration (2026)
Tailwind CSS v4 with Next.js 16 goes CSS-first: @import 'tailwindcss', delete the config file, and define tokens in @theme. Covers setup, dark mode gotchas, Turbopack HMR fixes for monorepos, and the parts of v3-to-v4 migration the codemod misses.