Tailwind v4 shadcn

Tailwind v4 + shadcn/ui Production Stack

Production-tested: WordPress Auditor (https://wordpress-auditor.webfonts.workers.dev) Last Updated: 2025-10-29 Status: Production Ready ✅

---

⚠️ 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

pnpm add tailwindcss @tailwindcss/vite
pnpm add -D @types/node
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

Symptom	Cause	Fix
bg-primary doesn't work	Missing @theme inline mapping	Add @theme inline block
Colors all black/white	Double hsl() wrapping	Use var(--color) not hsl(var(--color))
Dark mode not switching	Missing ThemeProvider	Wrap app in <ThemeProvider>
Build fails	tailwind.config.ts exists	Delete the file
Text invisible	Wrong contrast colors	Check color definitions in :root/.dark

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

---

File Templates

All templates are available in the templates/ directory:

• 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.

---

Complete Setup Checklist

• Vite + React + TypeScript project created
• @tailwindcss/vite installed (NOT postcss)
• vite.config.ts uses tailwindcss() plugin
• tsconfig.json has path aliases configured
• components.json exists with "config": ""
• NO tailwind.config.ts file exists
• src/index.css follows v4 pattern:
  • :root and .dark at root level (not in @layer)
  • Colors wrapped with hsl()
  • @theme inline maps all variables
  • @layer base uses unwrapped variables
• Theme provider installed and wrapping app
• Dark mode toggle component created
• Test theme switching works in browser

---

Advanced Topics

Custom Colors

Add new semantic colors:

:root {
  --brand: hsl(280 65% 60%);
  --brand-foreground: hsl(0 0% 100%);
}

.dark {
  --brand: hsl(280 75% 70%);
  --brand-foreground: hsl(280 20% 10%);
}

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

Usage: <div className="bg-brand text-brand-foreground">Branded</div>

Migration from v3

See reference/migration-guide.md for complete v3 → v4 migration steps.

Component Best Practices

1. Always use semantic tokens

   <Button variant="destructive">Delete</Button>  /* ✅ */
   <Button className="bg-red-600">Delete</Button>  /* ❌ */
   

2. Use cn() for conditional styling

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

3. Compose shadcn/ui components

   <Dialog>
     <DialogTrigger asChild>
       <Button>Open</Button>
     </DialogTrigger>
     <DialogContent>
       <DialogHeader>
         <DialogTitle>Title</DialogTitle>
       </DialogHeader>
     </DialogContent>
   </Dialog>
   

---

Dependencies

✅ Install These

{
  "dependencies": {
    "tailwindcss": "^4.1.14",
    "@tailwindcss/vite": "^4.1.14",
    "clsx": "^2.1.1",
    "tailwind-merge": "^3.3.1",
    "@radix-ui/react-*": "latest",
    "lucide-react": "^0.545.0",
    "react": "^19.2.0",
    "react-dom": "^19.2.0"
  },
  "devDependencies": {
    "@types/node": "^24.0.0",
    "@vitejs/plugin-react": "^5.0.4",
    "vite": "^7.0.0",
    "typescript": "~5.9.0"
  }
}

❌ NEVER Install These (Deprecated in v4)

# These packages will cause build errors:
npm install tailwindcss-animate  # ❌ Deprecated
npm install tw-animate-css      # ❌ Doesn't exist

If you see import errors for these packages, remove them and use native CSS animations or @tailwindcss/motion instead.

---

Tailwind v4 Plugins

Tailwind v4 supports official plugins using the @plugin directive in CSS.

Official Plugins (Tailwind Labs)

Typography Plugin - Style Markdown/CMS Content

When to use: Displaying blog posts, documentation, or any HTML from Markdown/CMS.

Installation:

pnpm add -D @tailwindcss/typography

Configuration (v4 syntax):

/* src/index.css */
@import "tailwindcss";
@plugin "@tailwindcss/typography";

Usage:

<article class="prose lg:prose-xl dark:prose-invert">
  {{ markdown_content }}
</article>

Available classes:

• prose - Base typography styles
• prose-sm, prose-base, prose-lg, prose-xl, prose-2xl - Size variants
• dark:prose-invert - Dark mode styles

---

Forms Plugin - Reset Form Element Styles

When to use: Building custom forms without shadcn/ui components, or need consistent cross-browser form styling.

Installation:

pnpm add -D @tailwindcss/forms

Configuration (v4 syntax):

/* src/index.css */
@import "tailwindcss";
@plugin "@tailwindcss/forms";

What it does:

• Resets browser default form styles
• Makes form elements styleable with Tailwind utilities
• Fixes cross-browser inconsistencies for inputs, selects, checkboxes, radios

Note: Less critical for shadcn/ui users (they have pre-styled form components), but still useful for basic forms.

---

Common Plugin Errors

These errors happen when using v3 syntax in v4 projects:

❌ WRONG (v3 config file syntax):

// tailwind.config.js
module.exports = {
  plugins: [require('@tailwindcss/typography')]
}

❌ WRONG (@import instead of @plugin):

@import "@tailwindcss/typography";  /* Doesn't work */

✅ CORRECT (v4 @plugin directive):

/* src/index.css */
@import "tailwindcss";
@plugin "@tailwindcss/typography";
@plugin "@tailwindcss/forms";

---

Built-in Features (No Plugin Needed)

Container queries are built into Tailwind v4 core - no plugin needed:

<div className="@container">
  <div className="@md:text-lg">
    Responds to container width, not viewport
  </div>
</div>

❌ Don't install: @tailwindcss/container-queries (deprecated, now core feature)

---

Reference Documentation

For deeper understanding, see:

• architecture.md - Deep dive into the 4-step pattern
• dark-mode.md - Complete dark mode implementation
• common-gotchas.md - All the ways it can break (and fixes)
• migration-guide.md - Migrating hardcoded colors to CSS variables

---

Official Documentation

• shadcn/ui Vite Setup: https://ui.shadcn.com/docs/installation/vite
• shadcn/ui Tailwind v4 Guide: https://ui.shadcn.com/docs/tailwind-v4
• shadcn/ui Dark Mode (Vite): https://ui.shadcn.com/docs/dark-mode/vite
• Tailwind v4 Docs: https://tailwindcss.com/docs
• shadcn/ui Theming: https://ui.shadcn.com/docs/theming

---

Production Example

This skill is based on the WordPress Auditor project:

• Live: https://wordpress-auditor.webfonts.workers.dev
• Stack: Vite + React 19 + Tailwind v4 + shadcn/ui + Cloudflare Workers
• Dark Mode: Full system/light/dark support
• Version: Tailwind v4.1.14 + shadcn/ui latest (Oct 2025)

All patterns in this skill have been validated in production.

---

Questions? Issues?

1. Check reference/common-gotchas.md first
2. Verify all steps in the 4-step architecture
3. Ensure components.json has "config": ""
4. Delete tailwind.config.ts if it exists
5. Check official docs: https://ui.shadcn.com/docs/tailwind-v4