# Tailwind CSS Configuration

## CSS-First Configuration (v4.1+)

Use the `@theme` directive for CSS-based configuration:

```css
/* src/styles.css */
@import "tailwindcss";

@theme {
  /* Custom colors */
  --color-brand-50: #f0f9ff;
  --color-brand-500: #3b82f6;
  --color-brand-900: #1e3a8a;

  /* Custom fonts */
  --font-display: "Inter", system-ui, sans-serif;
  --font-mono: "Fira Code", monospace;

  /* Custom spacing */
  --spacing-128: 32rem;

  /* Custom animations */
  --animate-fade-in: fadeIn 0.5s ease-in-out;

  /* Custom breakpoints */
  --breakpoint-3xl: 1920px;
}

/* Define custom animations */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* Custom utilities */
@utility content-auto {
  content-visibility: auto;
}
```

---

## JavaScript Configuration (Legacy)

```javascript
/** @type {import('tailwindcss').Config} */
export default {
  content: [
    "./index.html",
    "./src/**/*.{js,ts,jsx,tsx,vue,svelte}",
  ],
  theme: {
    extend: {
      colors: {
        primary: {
          50: '#f0f9ff',
          500: '#3b82f6',
          900: '#1e3a8a',
        },
      },
      fontFamily: {
        sans: ['Inter', 'system-ui', 'sans-serif'],
      },
      spacing: {
        '128': '32rem',
      },
    },
  },
  plugins: [],
}
```

---

## Vite Integration (v4.1+)

```javascript
// vite.config.ts
import { defineConfig } from 'vite'
import tailwindcss from '@tailwindcss/vite'

export default defineConfig({
  plugins: [
    tailwindcss(),
  ],
})
```

---

## Advanced v4.1 Features

### Native CSS Custom Properties

```html
<div class="bg-[var(--color-brand-500)] text-[var(--color-white)]">
  Using CSS custom properties directly
</div>
```

### Enhanced Arbitrary Values

```html
<!-- Complex grid with custom tracks -->
<div class="grid grid-cols-[repeat(auto-fit,minmax(250px,1fr))] gap-4">
  Responsive grid without custom CSS
</div>

<!-- Custom animation timing -->
<div class="animate-bounce ease-[cubic-bezier(0.68,-0.55,0.265,1.55)]">
  Bounce with custom easing
</div>
```

### Custom Utilities

```css
@utility content-auto {
  content-visibility: auto;
}

@utility text-shadow {
  text-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
```

---

## Plugins

### Custom Plugin Example

```javascript
// tailwind.config.js
const plugin = require('tailwindcss/plugin')

module.exports = {
  plugins: [
    plugin(function({ addUtilities, addComponents, e, config }) {
      // Add custom utilities
      addUtilities({
        '.content-auto': {
          contentVisibility: 'auto',
        },
      })

      // Add custom components
      addComponents({
        '.btn': {
          padding: '.5rem 1rem',
          borderRadius: '.25rem',
          fontWeight: '600',
        },
      })
    }),
  ],
}
```

---

## Presets

### Creating a Reusable Preset

```javascript
// tailwind-preset.js
module.exports = {
  theme: {
    extend: {
      colors: {
        brand: {
          DEFAULT: '#3b82f6',
          light: '#60a5fa',
          dark: '#1d4ed8',
        },
      },
    },
  },
  plugins: [
    require('@tailwindcss/forms'),
    require('@tailwindcss/typography'),
  ],
}
```

### Using a Preset

```javascript
// tailwind.config.js
module.exports = {
  presets: [
    require('./tailwind-preset.js'),
  ],
}
```