Tailwind CSS - Configuration

Tailwind CSS is highly customizable through its configuration file, allowing you to define your design system, extend the default theme, and configure plugins.

Key Concepts

Configuration File Structure

The tailwind.config.js (or .ts, .cjs, .mjs) file is the heart of Tailwind customization:

/** @type {import('tailwindcss').Config} */
module.exports = {
  content: [
    './src/**/*.{html,js,jsx,ts,tsx}',
    './pages/**/*.{js,ts,jsx,tsx}',
    './components/**/*.{js,ts,jsx,tsx}',
  ],
  theme: {
    extend: {
      // Custom theme extensions
    },
  },
  plugins: [],
  darkMode: 'class', // or 'media'
  prefix: '',
  important: false,
  separator: ':',
}

Content Configuration

The content array tells Tailwind where to look for class names:

module.exports = {
  content: [
    './src/**/*.{html,js,jsx,ts,tsx}',
    './pages/**/*.{js,ts,jsx,tsx}',
    './components/**/*.{js,ts,jsx,tsx}',
    './app/**/*.{js,ts,jsx,tsx}',
    './public/index.html',
  ],
  // ...
}

Content with Transform

For dynamic class names, use safelist or content transform:

module.exports = {
  content: {
    files: ['./src/**/*.{html,js}'],
    transform: {
      md: (content) => {
        // Extract classes from markdown
        return content
      }
    }
  },
  safelist: [
    'bg-red-500',
    'bg-green-500',
    {
      pattern: /bg-(red|green|blue)-(100|200|300)/,
    },
  ],
}

Theme Customization

Extending the Default Theme

Use theme.extend to add to existing values without replacing them:

module.exports = {
  theme: {
    extend: {
      colors: {
        brand: {
          50: '#f0f9ff',
          100: '#e0f2fe',
          200: '#bae6fd',
          300: '#7dd3fc',
          400: '#38bdf8',
          500: '#0ea5e9',
          600: '#0284c7',
          700: '#0369a1',
          800: '#075985',
          900: '#0c4a6e',
          950: '#082f49',
        },
        primary: '#0ea5e9',
        secondary: '#8b5cf6',
      },
      fontFamily: {
        sans: ['Inter', 'system-ui', 'sans-serif'],
        serif: ['Merriweather', 'serif'],
        mono: ['Fira Code', 'monospace'],
      },
      spacing: {
        '72': '18rem',
        '84': '21rem',
        '96': '24rem',
        '128': '32rem',
      },
      borderRadius: {
        '4xl': '2rem',
        '5xl': '2.5rem',
      },
      fontSize: {
        'xxs': '0.625rem',
      },
      boxShadow: {
        'inner-lg': 'inset 0 2px 4px 0 rgba(0, 0, 0, 0.06)',
      },
      animation: {
        'spin-slow': 'spin 3s linear infinite',
        'bounce-slow': 'bounce 2s infinite',
      },
      keyframes: {
        wiggle: {
          '0%, 100%': { transform: 'rotate(-3deg)' },
          '50%': { transform: 'rotate(3deg)' },
        }
      },
    },
  },
}

Overriding Default Theme

Use theme (without extend) to replace default values:

module.exports = {
  theme: {
    // This replaces the default color palette entirely
    colors: {
      white: '#ffffff',
      black: '#000000',
      gray: {
        100: '#f7fafc',
        // ... custom gray scale
        900: '#1a202c',
      },
      blue: {
        500: '#0ea5e9',
      },
    },
  },
}

Best Practices

1. Use CSS Variables for Dynamic Colors

Combine Tailwind with CSS variables for runtime theme switching:

// tailwind.config.js
module.exports = {
  theme: {
    extend: {
      colors: {
        primary: 'rgb(var(--color-primary) / <alpha-value>)',
        secondary: 'rgb(var(--color-secondary) / <alpha-value>)',
      },
    },
  },
}

/* globals.css */
:root {
  --color-primary: 14 165 233; /* RGB values */
  --color-secondary: 139 92 246;
}

[data-theme='dark'] {
  --color-primary: 56 189 248;
  --color-secondary: 167 139 250;
}

2. Organize Theme Extensions

Group related customizations for maintainability:

const colors = require('./theme/colors')
const typography = require('./theme/typography')
const spacing = require('./theme/spacing')

module.exports = {
  theme: {
    extend: {
      ...colors,
      ...typography,
      ...spacing,
    },
  },
}

3. Use Plugins for Reusable Patterns

Create custom utilities with plugins:

const plugin = require('tailwindcss/plugin')

module.exports = {
  plugins: [
    plugin(function({ addUtilities, addComponents, theme }) {
      // Add custom utilities
      addUtilities({
        '.scrollbar-hide': {
          '-ms-overflow-style': 'none',
          'scrollbar-width': 'none',
          '&::-webkit-scrollbar': {
            display: 'none'
          }
        },
        '.text-balance': {
          'text-wrap': 'balance',
        }
      })

      // Add custom components
      addComponents({
        '.btn': {
          padding: theme('spacing.2') + ' ' + theme('spacing.4'),
          borderRadius: theme('borderRadius.md'),
          fontWeight: theme('fontWeight.semibold'),
          '&:hover': {
            opacity: 0.8,
          }
        }
      })
    })
  ],
}

4. Configure Dark Mode

Choose the appropriate dark mode strategy:

module.exports = {
  // Class-based (manual control)
  darkMode: 'class',

  // Or media query-based (system preference)
  // darkMode: 'media',

  // Or custom selector
  // darkMode: ['class', '[data-theme="dark"]'],
}

5. Optimize for Production

Configure for smaller bundle sizes:

module.exports = {
  content: [
    './src/**/*.{html,js,jsx,ts,tsx}',
  ],
  // Remove unused styles in production
  purge: {
    enabled: process.env.NODE_ENV === 'production',
  },
}

Examples

Complete TypeScript Configuration

import type { Config } from 'tailwindcss'

const config: Config = {
  content: [
    './pages/**/*.{js,ts,jsx,tsx,mdx}',
    './components/**/*.{js,ts,jsx,tsx,mdx}',
    './app/**/*.{js,ts,jsx,tsx,mdx}',
  ],
  theme: {
    extend: {
      colors: {
        brand: {
          DEFAULT: '#0ea5e9',
          light: '#38bdf8',
          dark: '#0284c7',
        },
      },
      fontFamily: {
        sans: ['var(--font-inter)', 'sans-serif'],
      },
      animation: {
        'fade-in': 'fadeIn 0.5s ease-in-out',
        'slide-up': 'slideUp 0.5s ease-out',
      },
      keyframes: {
        fadeIn: {
          '0%': { opacity: '0' },
          '100%': { opacity: '1' },
        },
        slideUp: {
          '0%': { transform: 'translateY(20px)', opacity: '0' },
          '100%': { transform: 'translateY(0)', opacity: '1' },
        },
      },
    },
  },
  plugins: [
    require('@tailwindcss/forms'),
    require('@tailwindcss/typography'),
    require('@tailwindcss/aspect-ratio'),
  ],
  darkMode: 'class',
}

export default config

Multi-Brand Configuration

const brandColors = {
  brandA: {
    primary: '#0ea5e9',
    secondary: '#8b5cf6',
  },
  brandB: {
    primary: '#10b981',
    secondary: '#f59e0b',
  },
}

const currentBrand = process.env.BRAND || 'brandA'

module.exports = {
  theme: {
    extend: {
      colors: {
        primary: brandColors[currentBrand].primary,
        secondary: brandColors[currentBrand].secondary,
      },
    },
  },
}

Framework-Specific Configurations

Next.js

// tailwind.config.js
module.exports = {
  content: [
    './pages/**/*.{js,ts,jsx,tsx}',
    './components/**/*.{js,ts,jsx,tsx}',
    './app/**/*.{js,ts,jsx,tsx}',
  ],
  theme: {
    extend: {},
  },
  plugins: [],
}

Vite + React

// tailwind.config.js
module.exports = {
  content: [
    './index.html',
    './src/**/*.{js,ts,jsx,tsx}',
  ],
  theme: {
    extend: {},
  },
  plugins: [],
}

Vue 3

// tailwind.config.js
module.exports = {
  content: [
    './index.html',
    './src/**/*.{vue,js,ts,jsx,tsx}',
  ],
  theme: {
    extend: {},
  },
  plugins: [],
}

Common Patterns

Design Tokens Integration

const designTokens = {
  colors: {
    primary: {
      50: '#eff6ff',
      500: '#3b82f6',
      900: '#1e3a8a',
    },
  },
  spacing: {
    xs: '0.25rem',
    sm: '0.5rem',
    md: '1rem',
    lg: '1.5rem',
    xl: '2rem',
  },
}

module.exports = {
  theme: {
    extend: {
      colors: designTokens.colors,
      spacing: designTokens.spacing,
    },
  },
}

Responsive Breakpoint Customization

module.exports = {
  theme: {
    screens: {
      'xs': '475px',
      'sm': '640px',
      'md': '768px',
      'lg': '1024px',
      'xl': '1280px',
      '2xl': '1536px',
      '3xl': '1920px',
    },
  },
}

Plugin Configuration

module.exports = {
  plugins: [
    // Official plugins
    require('@tailwindcss/forms')({
      strategy: 'class', // or 'base'
    }),
    require('@tailwindcss/typography')({
      className: 'prose',
    }),
    require('@tailwindcss/container-queries'),

    // Custom plugin
    require('./plugins/utilities'),
  ],
}

Anti-Patterns

❌ Don't Hardcode Values in Multiple Places

// Bad: Repeating values
module.exports = {
  theme: {
    extend: {
      spacing: {
        'custom': '17px',
      },
      width: {
        'custom': '17px',
      },
      height: {
        'custom': '17px',
      },
    },
  },
}

// Good: Use spacing scale consistently
module.exports = {
  theme: {
    extend: {
      spacing: {
        'custom': '17px',
      },
    },
  },
}
// Then use w-custom, h-custom, p-custom, etc.

❌ Don't Extend When You Mean to Replace

// Bad: Accidentally keeping default colors
module.exports = {
  theme: {
    extend: {
      colors: {
        // This adds to the default palette, doesn't replace it
        blue: { 500: '#custom-blue' }
      },
    },
  },
}

// Good: Be explicit about replacing
module.exports = {
  theme: {
    colors: {
      // This replaces the entire color palette
    },
  },
}

❌ Don't Use Overly Specific Content Paths

// Bad: Too specific, might miss files
module.exports = {
  content: [
    './src/components/Button.tsx',
    './src/components/Card.tsx',
    // ...hundreds of files
  ],
}

// Good: Use glob patterns
module.exports = {
  content: [
    './src/**/*.{js,jsx,ts,tsx}',
  ],
}

❌ Don't Forget to Configure safelist for Dynamic Classes

// Bad: Dynamic classes won't be included
<div className={`bg-${color}-500`}>

// Good: Add to safelist
module.exports = {
  safelist: [
    {
      pattern: /bg-(red|green|blue|yellow)-(500|600|700)/,
    },
  ],
}

// Better: Use complete class names
<div className={color === 'red' ? 'bg-red-500' : 'bg-blue-500'}>

Related Skills

• tailwind-utility-classes: Using Tailwind's utility classes effectively
• tailwind-components: Building reusable component patterns
• tailwind-plugins: Creating custom Tailwind plugins
• tailwind-performance: Optimizing Tailwind for production