Tailwind CSS Best Practices - Agent Guide

This skill provides comprehensive Tailwind CSS patterns and best practices for AI coding agents.

Skill Overview

Name: tailwind-best-practices Version: 1.0.0 Framework: Tailwind CSS v3.4+ / v4.0+ Rule Count: 29 rules across 8 categories License: MIT

When to Use This Skill

Activate this skill when:

• Writing or refactoring Tailwind CSS classes
• Implementing responsive designs with breakpoints
• Adding dark mode support to applications
• Creating reusable component patterns
• Configuring Tailwind theme customization (v3 config or v4 @theme)
• Migrating from Tailwind v3 to v4
• Building forms, buttons, cards, tables, navigation
• Optimizing Tailwind for production
• Questions about Tailwind utilities and patterns

Rule Categories

1. Responsive Design (CRITICAL - 6 rules)

Mobile-first responsive patterns are fundamental to every Tailwind project.

Key Concepts:

• Mobile-first: Base styles apply to all screens, add breakpoints upward
• Breakpoint order: sm: (640px) → md: (768px) → lg: (1024px) → xl: (1280px) → 2xl: (1536px)
• Container queries for component-scoped responsiveness
• Fluid typography with clamp() for smooth scaling
• Responsive grid systems with grid-cols-{n}

Common Patterns:

<!-- Mobile-first responsive layout -->
<div class="
  w-full           <!-- Mobile: full width -->
  sm:w-1/2         <!-- Tablet: half -->
  lg:w-1/3         <!-- Desktop: third -->
  px-4 md:px-8     <!-- Responsive spacing -->
">
  Content
</div>

Rules: resp-mobile-first, responsive-breakpoint-order, responsive-container-queries, responsive-fluid-typography, responsive-aspect-ratio, responsive-grid-system

2. Dark Mode (CRITICAL - 6 rules)

Modern applications require seamless light/dark theme support.

Key Concepts:

• Class strategy (darkMode: 'class') for manual toggle
• Media strategy (darkMode: 'media') for system preference
• Semantic color naming for maintainable themes
• Custom color palettes with full scales (50-950)
• Smooth transitions between themes

Common Patterns:

<!-- Dark mode aware component -->
<div class="
  bg-white dark:bg-gray-900
  text-gray-900 dark:text-white
  border border-gray-200 dark:border-gray-700
">
  Content adapts to theme
</div>

Rules: dark-setup, dark-class-strategy, dark-media-strategy, dark-color-scheme, dark-custom-colors, dark-transitions

3. Component Patterns (HIGH - 7 rules)

Reusable component patterns for consistent UI.

Key Concepts:

• Use clsx + tailwind-merge (cn utility) for conditional classes
• Component variants with proper type safety
• Consistent button, card, form, table, modal patterns
• Proper accessibility attributes
• Responsive component behavior

Common Patterns:

// Button with variants using cn utility
import { cn } from '@/lib/utils'

function Button({ variant = 'primary', size = 'md', className, children }) {
  return (
    <button className={cn(
      'inline-flex items-center justify-center rounded-lg font-medium transition-colors',
      'focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-offset-2',
      {
        'bg-blue-600 text-white hover:bg-blue-700': variant === 'primary',
        'bg-gray-100 text-gray-900 hover:bg-gray-200': variant === 'secondary',
      },
      {
        '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',
      },
      className
    )}>
      {children}
    </button>
  )
}

Rules: comp-clsx-cn, component-btn-variants, component-card-patterns, component-form-elements, component-modals, component-navigation, component-tables

4. Custom Configuration — v3 (HIGH - 6 rules)

Extending Tailwind's v3 theme via tailwind.config.js. For v4, use @theme {} instead.

Key Concepts:

• Always extend theme, don't override (preserves defaults)
• Use full color scales (50-950) for flexibility
• Font families with proper fallbacks
• Custom spacing for layout consistency
• Plugins for extended functionality
• Presets for shared configuration

Common Patterns:

// tailwind.config.js - Proper theme extension
const defaultTheme = require('tailwindcss/defaultTheme')

module.exports = {
  darkMode: 'class',
  theme: {
    extend: {
      colors: {
        brand: {
          50: '#eff6ff',
          500: '#3b82f6',
          950: '#172554',
        },
      },
      fontFamily: {
        sans: ['Inter var', ...defaultTheme.fontFamily.sans],
      },
      spacing: {
        '18': '4.5rem',
        'header': '4rem',
      },
    },
  },
  plugins: [
    require('@tailwindcss/forms'),
    require('@tailwindcss/typography'),
  ],
}

Rules: config-extend-theme, config-custom-colors, config-custom-fonts, config-custom-spacing, config-plugins, config-presets

5. V4 & Migration (HIGH - 4 rules)

Tailwind CSS v4 setup, configuration, and migration from v3.

Key Concepts:

• CSS-first architecture: @import "tailwindcss" replaces @tailwind directives
• @theme {} replaces tailwind.config.js for design tokens
• @utility and @custom-variant replace JS plugin API
• @variant for nesting variants in custom CSS
• @reference for importing without emitting CSS
• @source / @source not for scan control
• New features: starting:, forced-colors:, color-mix(), transition-discrete
• Container queries and aspect-ratio built into core (no plugins)

Common Patterns:

@import "tailwindcss";

@theme {
  --color-brand-500: #3b82f6;
  --font-sans: "Inter", sans-serif;
}

@utility scrollbar-hide {
  scrollbar-width: none;
}

@custom-variant hocus (&:hover, &:focus);

Rules: v4-installation, v4-theme-configuration, v4-custom-utilities, v4-migration

6. Spacing & Typography (MEDIUM - 0 rules)

Consistent spacing and typography systems.

Key Concepts:

• Use Tailwind's spacing scale (0-96)
• Custom spacing only when needed
• Typography scale with line heights
• Responsive text sizing
• Vertical rhythm

Future Rules: To be added based on common patterns

7. Animation (MEDIUM - 0 rules)

Smooth transitions and animations.

Key Concepts:

• Transition utilities for state changes
• Custom keyframe animations
• Respect prefers-reduced-motion
• Performance considerations

Future Rules: To be added based on common patterns

8. Performance (LOW - 0 rules)

Build and runtime optimization.

Key Concepts:

• Content configuration for tree-shaking
• JIT mode benefits
• Arbitrary value usage
• Bundle size optimization

Future Rules: To be added based on common patterns

Tailwind CSS v4 Quick Reference

When working with Tailwind v4, be aware of these key differences from v3:

Setup

/* Single import replaces @tailwind directives */
@import "tailwindcss";

Configuration

/* @theme replaces tailwind.config.js */
@theme {
  --color-brand-500: #3b82f6;
  --font-sans: "Inter", sans-serif;
  --breakpoint-3xl: 1920px;
}

Custom Code

/* @utility replaces addUtilities() and @layer components */
@utility scrollbar-hide { scrollbar-width: none; }

/* @custom-variant replaces addVariant() */
@custom-variant hocus (&:hover, &:focus);

/* @variant for nesting in custom CSS */
.card {
  background: white;
  @variant dark { background: #1e293b; }
}

/* @plugin replaces require() in config */
@plugin "@tailwindcss/forms";

/* @reference for @apply without emitting CSS */
@reference "tailwindcss";

New Variants and Features

<!-- starting: for @starting-style animations -->
<div popover class="transition-discrete starting:open:opacity-0">

<!-- forced-colors: for Windows High Contrast -->
<input class="appearance-none forced-colors:appearance-auto">

<!-- Container query ranges (built-in, no plugin) -->
<div class="@container">
  <div class="@min-sm:@max-lg:grid-cols-2">Range query</div>
</div>

<!-- Dynamic values — no config needed -->
<div class="grid-cols-15 px-17">

Plugins No Longer Needed

• @tailwindcss/aspect-ratio — native aspect-* utilities
• @tailwindcss/container-queries — native @container with range variants

Agent Workflow

1. Analyze Requirements

• Is this responsive? Use mobile-first approach
• Does it need dark mode? Apply dark: variants
• Is it a reusable component? Use cn utility
• Custom colors/fonts? Extend theme properly

2. Write Classes

• Start with base styles (display, sizing)
• Add responsive breakpoints (mobile-first)
• Include dark mode variants
• Add interactive states (hover, focus, active)
• Apply transitions for smooth UX

3. Component Pattern

// Standard component structure
<ComponentName
  className={cn(
    // Base
    'base styles',

    // Responsive
    'mobile lg:desktop',

    // Colors + Dark Mode
    'bg-white dark:bg-gray-900',
    'text-gray-900 dark:text-white',

    // Interactive
    'hover:bg-gray-50',
    'focus:ring-2',

    // Transitions
    'transition-colors duration-200',

    // Allow override
    className
  )}
/>

4. Verify Patterns

• ✅ Mobile-first breakpoint order
• ✅ Dark mode coverage
• ✅ Accessibility (ARIA, semantic HTML)
• ✅ Interactive states
• ✅ No conflicting utilities
• ✅ Proper transitions

Essential Utilities Reference

Layout

<!-- Flexbox -->
<div class="flex items-center justify-between gap-4">

<!-- Grid -->
<div class="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-3 gap-6">

<!-- Container -->
<div class="container mx-auto px-4 max-w-7xl">

Spacing

<!-- Padding: p-{size}, px-{size}, py-{size} -->
<div class="p-6 px-4 py-8">

<!-- Margin: m-{size}, mx-{size}, my-{size} -->
<div class="mt-4 mb-8 mx-auto">

<!-- Space between -->
<div class="space-y-4">

Colors

<!-- Background -->
<div class="bg-white dark:bg-gray-900">

<!-- Text -->
<p class="text-gray-900 dark:text-white">

<!-- Border -->
<div class="border border-gray-200 dark:border-gray-700">

Typography

<!-- Size -->
<h1 class="text-4xl md:text-5xl lg:text-6xl">

<!-- Weight -->
<p class="font-medium">

<!-- Line height -->
<p class="leading-relaxed">

Interactive States

<!-- Hover, focus, active -->
<button class="
  hover:bg-blue-700
  focus:outline-none focus:ring-2 focus:ring-blue-500
  active:bg-blue-800
">

Transitions

<!-- Smooth transitions -->
<div class="transition-colors duration-200">
<div class="transition-all duration-300 ease-in-out">

Common Anti-Patterns to Avoid

❌ Don't: Desktop-first breakpoints

<div class="w-1/4 lg:w-1/3 md:w-1/2 sm:w-full">

✅ Do: Mobile-first breakpoints

<div class="w-full sm:w-1/2 md:w-1/3 lg:w-1/4">

❌ Don't: Conflicting utilities

<div class="px-4 px-8">

✅ Do: Single utility or use cn

<div class={cn('px-4', condition && 'px-8')}>

❌ Don't: Override theme without extend (v3)

theme: {
  colors: { primary: '#blue' } // Lost all default colors!
}

✅ Do: Extend theme (v3) or use @theme (v4)

// v3
theme: { extend: { colors: { brand: {...} } } }

/* v4 — extends by default */
@theme { --color-brand-500: #3b82f6; }

❌ Don't: Arbitrary values for standard utilities

<div class="w-[100%]">

✅ Do: Use built-in utilities

<div class="w-full">

Quick Decision Tree

Question: Am I building a new component? → YES: Use cn utility, create variants, ensure dark mode support → NO: Continue

Question: Does it need to be responsive? → YES: Mobile-first, add breakpoints upward (sm: md: lg:) → NO: Continue

Question: Does it have interactive states? → YES: Add hover:, focus:, active:, disabled: states → NO: Continue

Question: Should it transition smoothly? → YES: Add transition-* utilities → NO: Done

Resources

• Documentation: https://tailwindcss.com/docs
• Playground: https://play.tailwindcss.com
• Component Library: https://tailwindui.com
• Icons: https://heroicons.com
• Tools: IntelliSense, Prettier Plugin, tailwind-merge

Getting Help

1. Check rule files in rules/ directory for specific patterns
2. Reference _template.md for rule structure
3. See metadata.json for official documentation links
4. Review _sections.md for category descriptions

Success Metrics

When this skill is applied correctly, you should see:

• ✅ Consistent responsive behavior across devices
• ✅ Seamless dark mode transitions
• ✅ Reusable, maintainable components
• ✅ Accessible, keyboard-navigable interfaces
• ✅ Fast build times and small bundle sizes
• ✅ Clean, readable class names
• ✅ No conflicting utilities
• ✅ Type-safe component APIs

Last Updated: 2026-03-07 Skill Version: 1.0.0 Maintainer: Agent Skills Contributors