Tailwind v4 Shadcn

Tailwind v4 + shadcn/ui Stack

Production-tested setup for Tailwind v4 with shadcn/ui. Prevents 8 documented errors through a mandatory four-step architecture.

WHAT

Complete Tailwind v4 + shadcn/ui configuration:

WHEN

KEYWORDS

tailwind v4, tailwindcss 4, shadcn, shadcn/ui, @theme inline, dark mode, css variables, vite, tw-animate-css, tailwind config, migration

Production verified: WordPress Auditor (https://wordpress-auditor.webfonts.workers.dev) Versions: tailwindcss@4.1.18, @tailwindcss/vite@4.1.18

Installation

OpenClaw / Moltbot / Clawbot

npx clawhub@latest install tailwind-v4-shadcn

Quick Start

# 1. Install dependencies
pnpm add tailwindcss @tailwindcss/vite
pnpm add -D @types/node tw-animate-css
pnpm dlx shadcn@latest init
2. Delete v3 config (v4 doesn't use it)
rm tailwind.config.ts

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') } }
})

components.json (CRITICAL):

{
  "tailwind": {
    "config": "",
    "css": "src/index.css",
    "baseColor": "slate",
    "cssVariables": true
  }
}

The Four-Step Architecture (MANDATORY)

Skipping steps breaks theming. Follow exactly:

Step 1: Define CSS Variables at Root

/* src/index.css */
@import "tailwindcss";
@import "tw-animate-css";
:root {
  --background: hsl(0 0% 100%);
  --foreground: hsl(222.2 84% 4.9%);
  --primary: hsl(221.2 83.2% 53.3%);
  --primary-foreground: hsl(210 40% 98%);
  /* ... all light mode colors with hsl() wrapper */
}
.dark {
  --background: hsl(222.2 84% 4.9%);
  --foreground: hsl(210 40% 98%);
  --primary: hsl(217.2 91.2% 59.8%);
  --primary-foreground: hsl(222.2 47.4% 11.2%);
  /* ... all dark mode colors */
}

Critical: Define at root level (NOT inside @layer base). Use hsl() wrapper.

Step 2: Map Variables to Tailwind

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

Why: Generates utility classes (bg-background, text-primary). Without this, utilities don't exist.

Step 3: Apply Base Styles

@layer base {
  body {
    background-color: var(--background);
    color: var(--foreground);
  }
}

Critical: Reference variables directly. Never double-wrap: hsl(var(--background)).

Step 4: Result - Automatic Dark Mode

  {/* Theme switches automatically via .dark class */}

No dark: variants needed for semantic colors.

Critical Rules

Always Do

Never Do

Common Errors & Solutions

Error 1: tw-animate-css Import

Error: Cannot find module 'tailwindcss-animate'

# Wrong (v3 package)
npm install tailwindcss-animate
Correct (v4 package)
pnpm add -D tw-animate-css

@import "tailwindcss";
@import "tw-animate-css";

Error 2: Colors Not Working

Error: bg-primary doesn't apply styles

Cause: Missing @theme inline mapping

@theme inline {
  --color-primary: var(--primary);
  /* Map ALL variables */
}

Error 3: Dark Mode Not Switching

Cause: Missing ThemeProvider

See templates/theme-provider.tsx and wrap your app.

Error 4: Build Fails

Error: Unexpected config file

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

Error 5: @theme inline Breaks Multi-Theme

Cause: @theme inline bakes values at build time

Use @theme (without inline) for multi-theme systems:

/* For multi-theme (not just light/dark) */
@theme {
  --color-text-primary: var(--color-slate-900);
}
@layer theme {
  [data-theme="dark"] {
    --color-text-primary: var(--color-white);
  }
}

Error 6: @apply Breaking

Error: Cannot apply unknown utility class

v4 changed @apply behavior:

/* Wrong (v3 pattern) */
@layer components {
  .custom-button { @apply px-4 py-2; }
}
/* Correct (v4 pattern) */
@utility custom-button {
  @apply px-4 py-2;
}

Error 7: @layer base Styles Ignored

Cause: CSS layer cascade issues

/* Better: Don't use @layer base for critical styles */
body {
  background-color: var(--background);
}

Quick Reference

| Symptom | Cause | Fix | |---------|-------|-----| | bg-primary doesn't work | Missing @theme inline | Add mapping | | Colors black/white | Double hsl() | Use var(--color) not hsl(var(--color)) | | Dark mode stuck | Missing ThemeProvider | Wrap app | | Build fails | tailwind.config.ts exists | Delete file | | Animation errors | Wrong package | Use tw-animate-css |

Tailwind v4 New Features

OKLCH Color Space

v4 uses OKLCH for perceptually uniform colors. Automatic sRGB fallbacks generated.

@theme {
  /* Modern approach */
  --color-brand: oklch(0.7 0.15 250);
  
  /* Legacy (still works) */
  --color-brand: hsl(240 80% 60%);
}

Container Queries (Built-in)

  

    Content responds to container width
  

Line Clamp (Built-in)

Truncate to 3 lines...

Plugins

@import "tailwindcss";
@plugin "@tailwindcss/typography";
@plugin "@tailwindcss/forms";

Migration from v3

Key Changes

1. Delete tailwind.config.ts 2. Move theme to CSS with @theme inline 3. Replace tailwindcss-animate → tw-animate-css 4. Replace require() → @plugin 5. @apply in @layer components → @utility

Color Migration

// Before: Hardcoded + dark variants
// After: Semantic + automatic

Visual Changes

Files

Setup Checklist

NEVER

# 1. Install dependencies
pnpm add tailwindcss @tailwindcss/vite
pnpm add -D @types/node tw-animate-css
pnpm dlx shadcn@latest init
2. Delete v3 config (v4 doesn't use it)
rm tailwind.config.ts

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') } }
})

components.json (CRITICAL):

{
  "tailwind": {
    "config": "",
    "css": "src/index.css",
    "baseColor": "slate",
    "cssVariables": true
  }
}