Tailwind CSS Best Practices

Comprehensive patterns for building consistent, maintainable interfaces with Tailwind CSS v3.4+ and v4. Contains 29 rules covering responsive design, dark mode, component patterns, configuration, and v4 migration.

Metadata

Version: 1.0.0
Framework: Tailwind CSS v3.4+ / v4.0+
Rule Count: 29 rules across 8 categories
License: MIT
Documentation: tailwindcss.com/docs

Step 1: Detect Tailwind Version

Always check the version before giving any advice. v3 and v4 are fundamentally different.

Check package.json for the installed version:

{ "tailwindcss": "^3.x" }  // → v3 rules apply
{ "tailwindcss": "^4.x" }  // → v4 rules apply

Also check for these signals:

Signal	Version
`tailwind.config.js` exists	v3
`@import "tailwindcss"` in CSS	v4
`@tailwindcss/vite` in dependencies	v4
`@tailwindcss/postcss` in dependencies	v4
`@theme {}` block in CSS	v4

If v3: Apply resp-, dark-, comp-, config- rules. Note that v4 is available. If v4: Apply v4- rules. tailwind.config.js patterns do NOT apply — use @theme {} instead. If migrating v3 → v4: Follow v4-migration rules directly.

When to Apply

Reference these guidelines when:

Writing responsive layouts
Implementing dark mode
Creating reusable component styles
Configuring Tailwind (v3 or v4)
Migrating a project from v3 to v4
Setting up a new project with v4

Rule Categories by Priority

Priority	Category	Impact	Prefix	Version
1	Responsive Design	CRITICAL	`resp-`	v3 / v4
2	Dark Mode	CRITICAL	`dark-`	v3 / v4
3	Component Patterns	HIGH	`comp-`	v3 / v4
4	Custom Configuration	HIGH	`config-`	v3
5	V4 & Migration	HIGH	`v4-`	v4 only
6	Spacing & Typography	MEDIUM	`space-`	v3 / v4
7	Animation	MEDIUM	`anim-`	v3 / v4
8	Performance	LOW	`perf-`	v3 / v4

Quick Reference

1. Responsive Design (CRITICAL)

resp-mobile-first - Mobile-first approach
resp-breakpoints - Use breakpoints correctly
resp-container - Container patterns
resp-grid-flex - Grid vs Flexbox decisions
resp-hidden-shown - Conditional display

2. Dark Mode (CRITICAL)

dark-setup - Configure dark mode
dark-classes - Apply dark mode classes
dark-toggle - Implement dark mode toggle
dark-system-preference - Respect system preference
dark-colors - Design for both modes

3. Component Patterns (HIGH)

comp-clsx-cn - Conditional classes utility
comp-variants - Component variants pattern
comp-slots - Slot-based components
comp-composition - Composing utilities

4. Custom Configuration — v3 only (HIGH)

config-extend - Extend vs override theme
config-colors - Custom color palette
config-fonts - Custom fonts
config-screens - Custom breakpoints
config-plugins - Using plugins

5. V4 & Migration (HIGH)

v4-installation - Install v4 with Vite or PostCSS, @source, @reference
v4-theme-configuration - Replace tailwind.config.js with @theme {} in CSS
v4-custom-utilities - @utility, @custom-variant, @variant, @plugin
v4-migration - Step-by-step v3 → v4 migration with renamed utilities, starting:, forced-colors:

6. Spacing & Typography (MEDIUM)

space-consistent - Consistent spacing scale
space-margins - Margin patterns
space-padding - Padding patterns
typo-scale - Typography scale
typo-line-height - Line height

7. Animation (MEDIUM)

anim-transitions - Transition utilities
anim-keyframes - Custom keyframes
anim-reduced-motion - Respect motion preferences

8. Performance (LOW)

perf-purge - Content configuration
perf-jit - JIT mode benefits
perf-arbitrary - Arbitrary values usage

Essential Patterns

Mobile-First Responsive Design

// ✅ Mobile-first: start with mobile, add larger breakpoints
<div className="
  w-full           // Mobile: full width
  md:w-1/2         // Tablet: half width
  lg:w-1/3         // Desktop: third width
">
  <p className="
    text-sm          // Mobile: small text
    md:text-base     // Tablet: base text
    lg:text-lg       // Desktop: large text
  ">
    Content
  </p>
</div>

// ❌ Don't think desktop-first
<div className="w-1/3 md:w-1/2 sm:w-full">  // Confusing

Dark Mode Implementation

v3 — tailwind.config.js:

module.exports = { darkMode: 'class' }

v4 — CSS only, no config file:

@import "tailwindcss";
/* dark mode is class-based by default in v4 — no config needed */

Component — identical in both versions:

<div className="bg-white dark:bg-gray-900 text-gray-900 dark:text-white">
  <h2 className="text-gray-900 dark:text-white">Title</h2>
  <p className="text-gray-600 dark:text-gray-400">Description</p>
</div>

function toggleDarkMode() {
  document.documentElement.classList.toggle('dark')
}

Conditional Classes with clsx/cn

import { clsx, type ClassValue } from 'clsx'
import { twMerge } from 'tailwind-merge'

// cn utility - merges Tailwind classes intelligently
export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs))
}

// Usage
interface ButtonProps {
  variant?: 'primary' | 'secondary' | 'danger'
  size?: 'sm' | 'md' | 'lg'
  className?: string
  children: React.ReactNode
}

function Button({ variant = 'primary', size = 'md', className, children }: ButtonProps) {
  return (
    <button
      className={cn(
        // Base styles
        'inline-flex items-center justify-center rounded-md font-medium transition-colors',
        'focus:outline-none focus:ring-2 focus:ring-offset-2',

        // Variants
        {
          'bg-blue-600 text-white hover:bg-blue-700 focus:ring-blue-500':
            variant === 'primary',
          'bg-gray-100 text-gray-900 hover:bg-gray-200 focus:ring-gray-500':
            variant === 'secondary',
          'bg-red-600 text-white hover:bg-red-700 focus:ring-red-500':
            variant === 'danger',
        },

        // Sizes
        {
          'px-3 py-1.5 text-sm': size === 'sm',
          'px-4 py-2 text-base': size === 'md',
          'px-6 py-3 text-lg': size === 'lg',
        },

        // Allow override
        className
      )}
    >
      {children}
    </button>
  )
}

Theme Configuration — v3 vs v4

v3 — tailwind.config.js:

/** @type {import('tailwindcss').Config} */
module.exports = {
  content: ['./resources/**/*.{blade.php,js,ts,jsx,tsx}'],
  darkMode: 'class',
  theme: {
    extend: {
      colors: { primary: { 500: '#0ea5e9', 600: '#0284c7' } },
      fontFamily: { sans: ['Inter', 'sans-serif'] },
      spacing: { '18': '4.5rem' },
    },
  },
  plugins: [require('@tailwindcss/forms')],
}

v4 — app.css only, no JS config:

@import "tailwindcss";

@theme {
  --color-primary-500: #0ea5e9;
  --color-primary-600: #0284c7;
  --font-sans: Inter, sans-serif;
  --spacing-18: 4.5rem;
  --breakpoint-3xl: 1920px;
}

See v4-theme-configuration and v4-migration rules for full details.

Responsive Grid Layout

// Product grid - responsive columns
<div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 xl:grid-cols-4 gap-6">
  {products.map(product => (
    <ProductCard key={product.id} product={product} />
  ))}
</div>

// Dashboard layout - sidebar + main
<div className="flex flex-col lg:flex-row min-h-screen">
  <aside className="
    w-full lg:w-64
    bg-gray-900
    lg:min-h-screen
  ">
    <nav>...</nav>
  </aside>
  <main className="flex-1 p-4 lg:p-8">
    <div className="max-w-7xl mx-auto">
      {children}
    </div>
  </main>
</div>

Form Styling

<form className="space-y-6">
  <div>
    <label htmlFor="email" className="block text-sm font-medium text-gray-700 dark:text-gray-300">
      Email
    </label>
    <input
      type="email"
      id="email"
      className="
        mt-1 block w-full rounded-md
        border-gray-300 dark:border-gray-600
        bg-white dark:bg-gray-800
        text-gray-900 dark:text-white
        shadow-sm
        focus:border-blue-500 focus:ring-blue-500
        disabled:bg-gray-100 disabled:cursor-not-allowed
      "
    />
  </div>

  <button
    type="submit"
    className="
      w-full flex justify-center
      py-2 px-4
      border border-transparent rounded-md
      shadow-sm text-sm font-medium
      text-white bg-blue-600
      hover:bg-blue-700
      focus:outline-none focus:ring-2 focus:ring-offset-2 focus:ring-blue-500
      disabled:opacity-50 disabled:cursor-not-allowed
    "
  >
    Submit
  </button>
</form>

Animations with Reduced Motion

// Respect user's motion preferences
<div className="
  transition-transform duration-300
  hover:scale-105
  motion-reduce:transition-none
  motion-reduce:hover:transform-none
">
  Card content
</div>

// Custom animation
<div className="animate-fade-in motion-reduce:animate-none">
  Content
</div>

// tailwind.config.js
module.exports = {
  theme: {
    extend: {
      keyframes: {
        'fade-in': {
          '0%': { opacity: '0' },
          '100%': { opacity: '1' },
        },
      },
      animation: {
        'fade-in': 'fade-in 0.3s ease-out',
      },
    },
  },
}

How to Use

Always run Step 1 (version detection) first, then read the relevant rule files:

v3 projects:

rules/config-extend-theme.md
rules/dark-setup.md
rules/comp-clsx-cn.md
rules/resp-mobile-first.md

v4 projects:

rules/v4-installation.md
rules/v4-theme-configuration.md
rules/v4-custom-utilities.md

Migrating v3 → v4:

rules/v4-migration.md

References

Tailwind CSS Documentation - Official documentation
Responsive Design Guide - Mobile-first patterns
Dark Mode Guide - Theme implementation
Configuration Guide - Customization
Tailwind UI - Official component library
Headless UI - Accessible components
Heroicons - Icon library

Ecosystem Tools

Tailwind CSS IntelliSense - VS Code autocomplete and linting
Prettier Plugin - Automatic class sorting
tailwind-merge - Conflict-free class merging
clsx - Conditional class utility
CVA - Component variant system

License

MIT License - See repository for full license text.

This skill is part of the Agent Skills collection, providing AI-powered development assistance with industry best practices.

tailwind-best-practices