Tailwind V4 Shadcn

Tailwind v4 + shadcn/ui Production Stack

Production-tested: WordPress Auditor (https://wordpress-auditor.webfonts.workers.dev) Last Updated: 2025-12-04 Status: Production Ready ✅

Table of Contents

1. Before You Start
2. Quick Start
3. Four-Step Architecture
4. Dark Mode Setup
5. Critical Rules
6. Semantic Color Tokens
7. Common Issues & Fixes
8. File Templates
9. Setup Checklist
10. Advanced Topics
11. Dependencies
12. Tailwind v4 Plugins
13. Reference Documentation
14. When to Load References

⚠️ BEFORE YOU START (READ THIS!)

CRITICAL FOR AI AGENTS: If you're Claude Code helping a user set up Tailwind v4:

1. Explicitly state you're using this skill at the start of the conversation
2. Reference patterns from the skill rather than general knowledge
3. Prevent known issues listed in reference/common-gotchas.md
4. Don't guess - if unsure, check the skill documentation

USER ACTION REQUIRED: Tell Claude to check this skill first!

Say: "I'm setting up Tailwind v4 + shadcn/ui - check the tailwind-v4-shadcn skill first"

Why This Matters (Real-World Results)

Without skill activation:

• ❌ Setup time: ~5 minutes
• ❌ Errors encountered: 2-3 (tw-animate-css, duplicate @layer base)
• ❌ Manual fixes needed: 2+ commits
• ❌ Token usage: ~65k
• ❌ User confidence: Required debugging

With skill activation:

• ✅ Setup time: ~1 minute
• ✅ Errors encountered: 0
• ✅ Manual fixes needed: 0
• ✅ Token usage: ~20k (70% reduction)
• ✅ User confidence: Instant success

Known Issues This Skill Prevents

1. tw-animate-css import error (deprecated in v4)
2. Duplicate @layer base blocks (shadcn init adds its own)
3. Wrong template selection (vanilla TS vs React)
4. Missing post-init cleanup (incompatible CSS rules)
5. Wrong plugin syntax (using @import or require() instead of @plugin directive)

All of these are handled automatically when the skill is active.

Quick Start (5 Minutes - Follow This Exact Order)

1. Install Dependencies

bun add tailwindcss @tailwindcss/vite
# or: npm install tailwindcss @tailwindcss/vite

bun add -d @types/node

# Note: Using pnpm for shadcn init due to known Bun compatibility issues
# (bunx has "Script not found" and postinstall/msw problems)
pnpm dlx shadcn@latest init

2. Configure Vite

// vite.config.ts
import { defineConfig } from 'vite';
import react from '@vitejs/plugin-react';
import tailwindcss from '@tailwindcss/vite';
import path from 'path';

export default defineConfig({
	plugins: [react(), tailwindcss()],
	resolve: {
		alias: {
			'@': path.resolve(__dirname, './src')
		}
	}
});

3. Update components.json

{
	"tailwind": {
		"config": "", // ← CRITICAL: Empty for v4
		"css": "src/index.css",
		"cssVariables": true
	}
}

4. Delete tailwind.config.ts

rm tailwind.config.ts  # v4 doesn't use this file

The Four-Step Architecture (CRITICAL)

This pattern is mandatory - skipping steps will break your theme.

Step 1: Define CSS Variables at Root Level

/* src/index.css */
@import 'tailwindcss';

:root {
	--background: hsl(0 0% 100%); /* ← hsl() wrapper required */
	--foreground: hsl(222.2 84% 4.9%);
	--primary: hsl(221.2 83.2% 53.3%);
	/* ... all light mode colors */
}

.dark {
	--background: hsl(222.2 84% 4.9%);
	--foreground: hsl(210 40% 98%);
	--primary: hsl(217.2 91.2% 59.8%);
	/* ... all dark mode colors */
}

Critical Rules:

• ✅ Define at root level (NOT inside @layer base)
• ✅ Use hsl() wrapper on all color values
• ✅ Use .dark for dark mode (NOT .dark { @theme { } })

Step 2: Map Variables to Tailwind Utilities

@theme inline {
	--color-background: var(--background);
	--color-foreground: var(--foreground);
	--color-primary: var(--primary);
	/* ... map ALL CSS variables */
}

Why This Is Required:

• Generates utility classes (bg-background, text-primary)
• Without this, bg-primary etc. won't exist

Step 3: Apply Base Styles

@layer base {
	body {
		background-color: var(--background); /* NO hsl() here */
		color: var(--foreground);
	}
}

Critical Rules:

• ✅ Reference variables directly: var(--background)
• ❌ Never double-wrap: hsl(var(--background))

Step 4: Result - Automatic Dark Mode

<div className="bg-background text-foreground">{/* No dark: variants needed - theme switches automatically */}</div>

Dark Mode Setup

1. Create ThemeProvider

See reference/dark-mode.md for full implementation or use template:

// Copy from: templates/theme-provider.tsx

2. Wrap Your App

// src/main.tsx
import { ThemeProvider } from '@/components/theme-provider'

ReactDOM.createRoot(document.getElementById('root')!).render(
  <React.StrictMode>
    <ThemeProvider defaultTheme="dark" storageKey="vite-ui-theme">
      <App />
    </ThemeProvider>
  </React.StrictMode>,
)

3. Add Theme Toggle

pnpm dlx shadcn@latest add dropdown-menu

See reference/dark-mode.md for ModeToggle component code.

Critical Rules (MUST FOLLOW)

✅ Always Do:

1. Wrap color values with hsl() in :root and .dark

   --background: hsl(0 0% 100%); /* ✅ Correct */

2. Use @theme inline to map all CSS variables

   @theme inline {
       --color-background: var(--background);
   }

3. Set "tailwind.config": "" in components.json

   { "tailwind": { "config": "" } }

4. Delete tailwind.config.ts if it exists

5. Use @tailwindcss/vite plugin (NOT PostCSS)

6. Use cn() for conditional classes

   import { cn } from "@/lib/utils"
   <div className={cn("base", isActive && "active")} />

❌ Never Do:

1. Put :root or .dark inside @layer base

   /* WRONG */
   @layer base {
       :root {
           --background: hsl(...);
       }
   }

2. Use .dark { @theme { } } pattern

   /* WRONG - v4 doesn't support nested @theme */
   .dark {
       @theme {
           --color-primary: hsl(...);
       }
   }

3. Double-wrap colors

   /* WRONG */
   body {
       background-color: hsl(var(--background));
   }

4. Use tailwind.config.ts for theme colors

   /* WRONG - v4 ignores this */
   export default {
       theme: {
           extend: {
               colors: { primary: 'hsl(var(--primary))' }
           }
       }
   };

5. Use @apply directive (deprecated in v4)

6. Use dark: variants for semantic colors

   /* WRONG */
   <div className="bg-primary dark:bg-primary-dark" />
   
   /* CORRECT */
   <div className="bg-primary" />

Semantic Color Tokens

Always use semantic names for colors:

:root {
	--destructive: hsl(0 84.2% 60.2%); /* Red - errors, critical */
	--success: hsl(142.1 76.2% 36.3%); /* Green - success states */
	--warning: hsl(38 92% 50%); /* Yellow - warnings */
	--info: hsl(221.2 83.2% 53.3%); /* Blue - info, primary */
}

Usage:

<div className="bg-destructive text-destructive-foreground">Critical</div>
<div className="bg-success text-success-foreground">Success</div>
<div className="bg-warning text-warning-foreground">Warning</div>
<div className="bg-info text-info-foreground">Info</div>

Common Issues & Quick Fixes

See reference/common-gotchas.md for complete troubleshooting guide.

File Templates

All templates are available in the templates/ work:

• index.css - Complete CSS setup with all color variables
• components.json - shadcn/ui v4 configuration
• vite.config.ts - Vite + Tailwind plugin setup
• tsconfig.app.json - TypeScript with path aliases
• theme-provider.tsx - Dark mode provider with localStorage
• utils.ts - cn() utility for class merging

Copy these files to your project and customize as needed.