Tailwind CSS Core Knowledge
Deep Knowledge: Use mcp__documentation__fetch_docs with technology: tailwindcss for comprehensive documentation.
Common Utilities
<!-- Layout -->
<div class="flex items-center justify-between gap-4">
<div class="grid grid-cols-3 gap-4">
<div class="container mx-auto px-4">
<!-- Spacing -->
<div class="p-4 m-2 space-y-4">
<div class="px-4 py-2 mt-8 mb-4">
<!-- Sizing -->
<div class="w-full h-screen max-w-md min-h-[200px]">
<!-- Typography -->
<p class="text-lg font-semibold text-gray-900">
<p class="text-sm text-gray-500 leading-relaxed">
<!-- Colors -->
<div class="bg-blue-500 text-white border-gray-200">
<div class="bg-gradient-to-r from-blue-500 to-purple-500">
Responsive Design
<!-- Mobile-first breakpoints -->
<div class="text-sm md:text-base lg:text-lg">
<div class="flex-col md:flex-row">
<div class="hidden lg:block">
<!-- Breakpoints: sm(640) md(768) lg(1024) xl(1280) 2xl(1536) -->
States
<!-- Hover, Focus, Active -->
<button class="bg-blue-500 hover:bg-blue-600 active:bg-blue-700">
<input class="border focus:ring-2 focus:ring-blue-500 focus:border-blue-500">
<!-- Group hover -->
<div class="group">
<span class="group-hover:text-blue-500">Text</span>
</div>
<!-- Dark mode -->
<div class="bg-white dark:bg-gray-900 text-gray-900 dark:text-white">
Components Pattern
<!-- Card -->
<div class="rounded-lg shadow-md bg-white p-6 hover:shadow-lg transition-shadow">
<!-- Button -->
<button class="px-4 py-2 rounded-md bg-blue-500 text-white font-medium
hover:bg-blue-600 focus:outline-none focus:ring-2
focus:ring-blue-500 focus:ring-offset-2
disabled:opacity-50 disabled:cursor-not-allowed">
<!-- Input -->
<input class="w-full px-3 py-2 border border-gray-300 rounded-md
focus:outline-none focus:ring-2 focus:ring-blue-500
focus:border-transparent">
When NOT to Use This Skill
- CSS-in-JS preferred - Use styled-components or Emotion
- Traditional CSS workflow - Stick with SCSS/PostCSS
- Component library projects - Material-UI, Ant Design have their own styling
- Email templates - Inline styles required
Config
// tailwind.config.js
export default {
content: ['./src/**/*.{js,ts,jsx,tsx}'],
theme: {
extend: {
colors: { brand: '#1a73e8' },
fontFamily: { sans: ['Inter', 'sans-serif'] }
}
},
plugins: [require('@tailwindcss/forms')]
}
Anti-Patterns
| Anti-Pattern | Why It's Bad | Correct Approach |
|---|
| Using arbitrary values everywhere | Hard to maintain | Define in theme config |
| Long className strings | Hard to read | Use cn() utility or component extraction |
| Not using content config | Large CSS bundles | Specify exact file paths |
| Inline @apply in HTML | Defeats utility-first | Use @apply in CSS or extract component |
| Ignoring purge warnings | Unused CSS in production | Fix content paths |
| Not using CSS variables | Can't change dynamically | Use CSS vars for themeable values |
Quick Troubleshooting
| Issue | Cause | Solution |
|---|
| Styles not applying | Purge removed classes | Add to safelist or fix content paths |
| Dark mode not working | darkMode not set | Set darkMode: 'class' in config |
| Custom colors not working | Not in theme.extend | Add to theme.extend.colors |
| Build size too large | Including too many files | Be specific in content patterns |
| Hover not working on touch | Using:hover only | Add focus states for accessibility |
| Class conflicts | Multiple utility classes | Use cn() with tailwind-merge |
Production Readiness
Performance Optimization
// tailwind.config.js
export default {
content: [
'./src/**/*.{js,ts,jsx,tsx}',
// Be specific to avoid scanning node_modules
],
theme: {
extend: {},
},
// Remove unused utilities in production
safelist: [
// Only if dynamically generated
{ pattern: /bg-(red|green|blue)-(100|500)/ },
],
// Disable unused core plugins
corePlugins: {
preflight: true,
// container: false, // if not using
},
};
// postcss.config.js
export default {
plugins: {
'tailwindcss/nesting': {},
tailwindcss: {},
autoprefixer: {},
// Production only
...(process.env.NODE_ENV === 'production'
? { cssnano: { preset: 'default' } }
: {}),
},
};
Design System
// tailwind.config.js
export default {
theme: {
// Override defaults
colors: {
transparent: 'transparent',
current: 'currentColor',
white: '#ffffff',
black: '#000000',
// Brand colors
primary: {
50: '#eff6ff',
100: '#dbeafe',
500: '#3b82f6',
600: '#2563eb',
700: '#1d4ed8',
},
// Semantic colors
success: '#22c55e',
warning: '#f59e0b',
error: '#ef4444',
},
// Consistent spacing scale
spacing: {
px: '1px',
0: '0',
1: '0.25rem',
2: '0.5rem',
3: '0.75rem',
4: '1rem',
// ...
},
// Typography scale
fontSize: {
xs: ['0.75rem', { lineHeight: '1rem' }],
sm: ['0.875rem', { lineHeight: '1.25rem' }],
base: ['1rem', { lineHeight: '1.5rem' }],
lg: ['1.125rem', { lineHeight: '1.75rem' }],
xl: ['1.25rem', { lineHeight: '1.75rem' }],
},
},
};
Component Patterns
// lib/styles.ts - Reusable class compositions
import { clsx, type ClassValue } from 'clsx';
import { twMerge } from 'tailwind-merge';
export function cn(...inputs: ClassValue[]) {
return twMerge(clsx(inputs));
}
// Variant patterns with cva
import { cva, type VariantProps } from 'class-variance-authority';
export const buttonVariants = cva(
'inline-flex items-center justify-center rounded-md font-medium transition-colors focus-visible:outline-none focus-visible:ring-2 disabled:pointer-events-none disabled:opacity-50',
{
variants: {
variant: {
default: 'bg-primary-600 text-white hover:bg-primary-700',
outline: 'border border-gray-300 hover:bg-gray-50',
ghost: 'hover:bg-gray-100',
},
size: {
sm: 'h-8 px-3 text-sm',
md: 'h-10 px-4',
lg: 'h-12 px-6 text-lg',
},
},
defaultVariants: {
variant: 'default',
size: 'md',
},
}
);
Accessibility
<!-- Focus visible for keyboard users -->
<button class="focus:outline-none focus-visible:ring-2 focus-visible:ring-blue-500 focus-visible:ring-offset-2">
<!-- Skip link -->
<a href="#main" class="sr-only focus:not-sr-only focus:absolute focus:top-4 focus:left-4 focus:z-50 focus:px-4 focus:py-2 focus:bg-white">
Skip to content
</a>
<!-- Reduced motion -->
<div class="transition-transform motion-reduce:transition-none motion-reduce:transform-none">
<!-- Forced colors mode -->
<button class="bg-blue-500 forced-colors:bg-[ButtonFace] forced-colors:border forced-colors:border-[ButtonBorder]">
Dark Mode
// tailwind.config.js
export default {
darkMode: 'class', // or 'media'
// ...
};
// Theme toggle component
function ThemeToggle() {
const [theme, setTheme] = useState('light');
useEffect(() => {
document.documentElement.classList.toggle('dark', theme === 'dark');
}, [theme]);
return (
<button onClick={() => setTheme(theme === 'light' ? 'dark' : 'light')}>
Toggle theme
</button>
);
}
Testing
// Visual regression testing
import { test, expect } from '@playwright/test';
test('button variants render correctly', async ({ page }) => {
await page.goto('/storybook/button');
// Screenshot comparison
await expect(page.locator('.button-primary')).toHaveScreenshot('button-primary.png');
await expect(page.locator('.button-outline')).toHaveScreenshot('button-outline.png');
});
// Unit testing class compositions
import { cn, buttonVariants } from '@/lib/styles';
describe('buttonVariants', () => {
it('generates correct classes for default variant', () => {
const classes = buttonVariants({ variant: 'default', size: 'md' });
expect(classes).toContain('bg-primary-600');
expect(classes).toContain('h-10');
});
});
Monitoring Metrics
| Metric | Target |
|---|
| CSS bundle size | < 30KB gzipped |
| Unused CSS | 0% |
| First Contentful Paint | < 1s |
| Lighthouse Performance | > 90 |
Checklist
- Content paths correctly configured
- PostCSS with cssnano in production
- Design tokens (colors, spacing, typography)
- cn() utility for class merging
- CVA for component variants
- Dark mode support
- Focus-visible for accessibility
- Reduced motion support
- Bundle size monitoring
- Visual regression tests
Reference Documentation