--- name: ui-builder description: Expert guide for building beautiful, responsive UI with React, Tailwind CSS, Shadcn/ui, and modern design patterns. Use when creating components, layouts, animations, or styling. --- # UI/UX Builder Skill ## Overview This skill helps you build beautiful, accessible, and responsive user interfaces using modern React patterns, Tailwind CSS, and component libraries like Shadcn/ui. ## Core Principles ### 1. Mobile-First Design - Start with mobile layout - Use responsive breakpoints: sm (640px), md (768px), lg (1024px), xl (1280px) - Test on multiple screen sizes ### 2. Accessibility - Use semantic HTML - Add ARIA labels where needed - Ensure keyboard navigation works - Maintain color contrast ratios - Support screen readers ### 3. Performance - Lazy load heavy components - Optimize images - Use CSS animations over JS when possible - Minimize re-renders ### 4. Consistency - Use design tokens (colors, spacing, typography) - Follow established patterns - Maintain visual hierarchy ## Tailwind CSS Patterns ### Layout ```typescript // Flex layouts

Left

Right

// Grid layouts

Card 1

Card 2

Card 3

// Container

Content

// Centering

Centered

``` ### Responsive Design ```typescript // Mobile first

Responsive text

// Hide/show by breakpoint

Desktop only

Mobile only

// Responsive padding/margin

Responsive padding

``` ### Colors & Themes ```typescript // Background colors

Content

// Text colors

Text

// Hover states // Focus states ``` ### Spacing ```typescript // Margin/Padding scale: 0, 1(4px), 2(8px), 4(16px), 6(24px), 8(32px), 12(48px), 16(64px)

Padding 16px

Margin top 32px, bottom 16px

Vertical spacing between children

Gap between flex/grid items

``` ## Common Component Patterns ### Button ```typescript // components/ui/button.tsx import { cn } from '@/lib/utils' interface ButtonProps extends React.ButtonHTMLAttributes { variant?: 'default' | 'outline' | 'ghost' | 'destructive' size?: 'sm' | 'md' | 'lg' } export function Button({ className, variant = 'default', size = 'md', ...props }: ButtonProps) { return ( )} {children} ) } ``` ### Dropdown Menu ```typescript 'use client' import { useState, useRef, useEffect } from 'react' export function DropdownMenu({ trigger, children }: { trigger: React.ReactNode children: React.ReactNode }) { const [open, setOpen] = useState(false) const ref = useRef(null) useEffect(() => { function handleClickOutside(event: MouseEvent) { if (ref.current && !ref.current.contains(event.target as Node)) { setOpen(false) } } document.addEventListener('mousedown', handleClickOutside) return () => document.removeEventListener('mousedown', handleClickOutside) }, []) return (

setOpen(!open)}>{trigger}

{open && (

{children}

)}

) } export function DropdownMenuItem({ children, onClick }: { children: React.ReactNode onClick?: () => void }) { return ( ) } ``` ### Form ```typescript // components/forms/contact-form.tsx 'use client' import { useState } from 'react' import { Input } from '@/components/ui/input' import { Button } from '@/components/ui/button' export function ContactForm() { const [loading, setLoading] = useState(false) const [errors, setErrors] = useState>({}) async function handleSubmit(e: React.FormEvent) { e.preventDefault() setLoading(true) setErrors({}) const formData = new FormData(e.currentTarget) const email = formData.get('email') as string const message = formData.get('message') as string // Validation const newErrors: Record = {} if (!email) newErrors.email = 'Email is required' if (!message) newErrors.message = 'Message is required' if (Object.keys(newErrors).length > 0) { setErrors(newErrors) setLoading(false) return } try { const response = await fetch('/api/contact', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ email, message }), }) if (!response.ok) throw new Error('Failed to send') // Success e.currentTarget.reset() alert('Message sent!') } catch (error) { setErrors({ submit: 'Failed to send message' }) } finally { setLoading(false) } } return (

Email {errors.email && (

{errors.email}

)}

Message

{errors.message && (
          <p className="mt-1 text-sm text-red-600">{errors.message}</p>
        )}
      </div>

{errors.submit && (
        <p className="text-sm text-red-600">{errors.submit}</p>
      )}

<Button type="submit" disabled={loading}>
        {loading ? 'Sending...' : 'Send Message'}
      </Button>
    </form>
  )
}
```

## Animations

### Tailwind Transitions

```typescript
// Hover effects
<div className="transition-all duration-200 hover:scale-105">
  Hover to scale
</div>

// Opacity fade
<div className="transition-opacity duration-300 opacity-0 hover:opacity-100">
  Fade in
</div>

// Transform
<div className="transition-transform duration-200 hover:translate-x-2">
  Slide on hover
</div>
```

### Framer Motion

```typescript
'use client'
import { motion } from 'framer-motion'

// Fade in
<motion.div
  initial={{ opacity: 0 }}
  animate={{ opacity: 1 }}
  transition={{ duration: 0.5 }}
>
  Fades in
</motion.div>

// Slide in
<motion.div
  initial={{ x: -100, opacity: 0 }}
  animate={{ x: 0, opacity: 1 }}
  transition={{ duration: 0.5 }}
>
  Slides in
</motion.div>

// Stagger children
<motion.div
  initial="hidden"
  animate="visible"
  variants={{
    visible: {
      transition: {
        staggerChildren: 0.1
      }
    }
  }}
>
  {items.map(item => (
    <motion.div
      key={item.id}
      variants={{
        hidden: { opacity: 0, y: 20 },
        visible: { opacity: 1, y: 0 }
      }}
    >
      {item.title}
    </motion.div>
  ))}
</motion.div>
```

## Icons

### Lucide React

```typescript
import { Search, User, Settings, ChevronRight } from 'lucide-react'

// Basic usage
<Search className="h-5 w-5" />

// With color
<User className="h-5 w-5 text-blue-600" />

// In button
<button className="flex items-center gap-2">
  <Settings className="h-4 w-4" />
  Settings
</button>
```

## Loading States

### Skeleton

```typescript
export function Skeleton({ className }: { className?: string }) {
  return (
    <div className={cn('animate-pulse rounded-md bg-gray-200', className)} />
  )
}

// Usage
<div className="space-y-4">
  <Skeleton className="h-12 w-full" />
  <Skeleton className="h-12 w-full" />
  <Skeleton className="h-12 w-3/4" />
</div>
```

### Spinner

```typescript
export function Spinner({ className }: { className?: string }) {
  return (
    <div
      className={cn(
        'animate-spin rounded-full border-2 border-gray-300 border-t-blue-600',
        'h-8 w-8',
        className
      )}
    />
  )
}
```

## Dark Mode

### Setup

```typescript
// app/providers.tsx
'use client'
import { ThemeProvider } from 'next-themes'

export function Providers({ children }: { children: React.ReactNode }) {
  return (
    <ThemeProvider attribute="class" defaultTheme="system" enableSystem>
      {children}
    </ThemeProvider>
  )
}

// app/layout.tsx
export default function RootLayout({ children }: { children: React.ReactNode }) {
  return (
    <html lang="en" suppressHydrationWarning>
      <body>
        <Providers>{children}</Providers>
      </body>
    </html>
  )
}
```

### Theme Toggle

```typescript
'use client'
import { useTheme } from 'next-themes'
import { Moon, Sun } from 'lucide-react'

export function ThemeToggle() {
  const { theme, setTheme } = useTheme()

return (
    <button
      onClick={() => setTheme(theme === 'dark' ? 'light' : 'dark')}
      className="rounded-md p-2 hover:bg-gray-100 dark:hover:bg-gray-800"
    >
      <Sun className="h-5 w-5 dark:hidden" />
      <Moon className="hidden h-5 w-5 dark:block" />
    </button>
  )
}
```

### Dark Mode Styles

```typescript
// Tailwind dark mode
<div className="bg-white dark:bg-gray-900 text-gray-900 dark:text-white">
  Dark mode aware
</div>

// tailwind.config.js
module.exports = {
  darkMode: 'class',
  theme: {
    extend: {
      colors: {
        background: 'hsl(var(--background))',
        foreground: 'hsl(var(--foreground))',
      }
    }
  }
}
```

## Best Practices

### Accessibility Checklist
- [ ] Use semantic HTML (header, nav, main, footer, article, section)
- [ ] Add alt text to images
- [ ] Ensure sufficient color contrast (4.5:1 for normal text)
- [ ] Support keyboard navigation (tab, enter, escape)
- [ ] Add ARIA labels where needed
- [ ] Use focus-visible for keyboard focus
- [ ] Test with screen reader

### Performance Checklist
- [ ] Use next/image for images
- [ ] Lazy load components not in viewport
- [ ] Minimize client-side JavaScript
- [ ] Use CSS animations over JS
- [ ] Implement loading skeletons
- [ ] Optimize font loading
- [ ] Use proper image formats (WebP, AVIF)

### Responsive Design Checklist
- [ ] Design mobile-first
- [ ] Test on multiple screen sizes
- [ ] Use responsive images
- [ ] Implement touch-friendly tap targets (44x44px minimum)
- [ ] Test landscape and portrait
- [ ] Handle safe areas on mobile
- [ ] Consider foldable devices

## Utility Function

```typescript
// lib/utils.ts
import { clsx, type ClassValue } from 'clsx'
import { twMerge } from 'tailwind-merge'

export function cn(...inputs: ClassValue[]) {
  return twMerge(clsx(inputs))
}
```

## Common Layouts

### Dashboard Layout

```typescript
export default function DashboardLayout({ children }: { children: React.ReactNode }) {
  return (
    <div className="flex h-screen">
      {/* Sidebar */}
      <aside className="w-64 border-r bg-gray-50">
        <nav className="p-4">Sidebar</nav>
      </aside>

{/* Main content */}
      <div className="flex-1 overflow-auto">
        <header className="border-b bg-white px-6 py-4">
          Header
        </header>
        <main className="p-6">{children}</main>
      </div>
    </div>
  )
}
```

### Landing Page Hero

```typescript
export function Hero() {
  return (
    <section className="flex min-h-screen items-center justify-center bg-gradient-to-b from-blue-50 to-white">
      <div className="container px-4 text-center">
        <h1 className="mb-6 text-5xl font-bold tracking-tight md:text-6xl lg:text-7xl">
          Your Amazing Product
        </h1>
        <p className="mx-auto mb-8 max-w-2xl text-lg text-gray-600 md:text-xl">
          A compelling description that explains what your product does
        </p>
        <div className="flex flex-col gap-4 sm:flex-row sm:justify-center">
          <Button size="lg">Get Started</Button>
          <Button size="lg" variant="outline">Learn More</Button>
        </div>
      </div>
    </section>
  )
}
```

## When to Use This Skill

Invoke this skill when:
- Building new UI components
- Creating layouts and page structures
- Implementing responsive design
- Adding animations and transitions
- Working with forms and inputs
- Implementing dark mode
- Ensuring accessibility
- Optimizing UI performance
- Creating loading states
- Building navigation components
</article></body></html>

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