This skill should be used when setting up, configuring, or initializing Tailwind CSS (v3 or v4) and shadcn/ui for Next.js 16 App Router projects. Configure dark mode, design tokens, base layout with header/sidebar, accessibility defaults, and generate example components. Includes comprehensive setup automation, theme customization, and production-ready patterns. Use when the user requests "setup Tailwind", "configure shadcn/ui", "add dark mode", "initialize design system", or "setup UI framework