agents/plugins/ui-design/skills/responsive-design/SKILL.md

name, description

name	description
responsive-design	Implement modern responsive layouts using container queries, fluid typography, CSS Grid, and mobile-first breakpoint strategies. Use when building adaptive interfaces, implementing fluid layouts, or creating component-level responsive behavior.

Responsive Design

Master modern responsive design techniques to create interfaces that adapt seamlessly across all screen sizes and device contexts.

When to Use This Skill

• Implementing mobile-first responsive layouts
• Using container queries for component-based responsiveness
• Creating fluid typography and spacing scales
• Building complex layouts with CSS Grid and Flexbox
• Designing breakpoint strategies for design systems
• Implementing responsive images and media
• Creating adaptive navigation patterns
• Building responsive tables and data displays

Core Capabilities

1. Container Queries

• Component-level responsiveness independent of viewport
• Container query units (cqi, cqw, cqh)
• Style queries for conditional styling
• Fallbacks for browser support

2. Fluid Typography & Spacing

• CSS clamp() for fluid scaling
• Viewport-relative units (vw, vh, dvh)
• Fluid type scales with min/max bounds
• Responsive spacing systems

3. Layout Patterns

• CSS Grid for 2D layouts
• Flexbox for 1D distribution
• Intrinsic layouts (content-based sizing)
• Subgrid for nested grid alignment

4. Breakpoint Strategy

• Mobile-first media queries
• Content-based breakpoints
• Design token integration
• Feature queries (@supports)

Quick Reference

Modern Breakpoint Scale

/* Mobile-first breakpoints */
/* Base: Mobile (< 640px) */
@media (min-width: 640px) { /* sm: Landscape phones, small tablets */ }
@media (min-width: 768px) { /* md: Tablets */ }
@media (min-width: 1024px) { /* lg: Laptops, small desktops */ }
@media (min-width: 1280px) { /* xl: Desktops */ }
@media (min-width: 1536px) { /* 2xl: Large desktops */ }

/* Tailwind CSS equivalent */
/* sm:  @media (min-width: 640px) */
/* md:  @media (min-width: 768px) */
/* lg:  @media (min-width: 1024px) */
/* xl:  @media (min-width: 1280px) */
/* 2xl: @media (min-width: 1536px) */

Key Patterns

Pattern 1: Container Queries

/* Define a containment context */
.card-container {
  container-type: inline-size;
  container-name: card;
}

/* Query the container, not the viewport */
@container card (min-width: 400px) {
  .card {
    display: grid;
    grid-template-columns: 200px 1fr;
    gap: 1rem;
  }

  .card-image {
    aspect-ratio: 1;
  }
}

@container card (min-width: 600px) {
  .card {
    grid-template-columns: 250px 1fr;
  }

  .card-title {
    font-size: 1.5rem;
  }
}

/* Container query units */
.card-title {
  /* 5% of container width, clamped between 1rem and 2rem */
  font-size: clamp(1rem, 5cqi, 2rem);
}

// React component with container queries
function ResponsiveCard({ title, image, description }) {
  return (
    <div className="@container">
      <article className="flex flex-col @md:flex-row @md:gap-4">
        <img
          src={image}
          alt=""
          className="w-full @md:w-48 @lg:w-64 aspect-video @md:aspect-square object-cover"
        />
        <div className="p-4 @md:p-0">
          <h2 className="text-lg @md:text-xl @lg:text-2xl font-semibold">
            {title}
          </h2>
          <p className="mt-2 text-muted-foreground @md:line-clamp-3">
            {description}
          </p>
        </div>
      </article>
    </div>
  );
}

Pattern 2: Fluid Typography

/* Fluid type scale using clamp() */
:root {
  /* Min size, preferred (fluid), max size */
  --text-xs: clamp(0.75rem, 0.7rem + 0.25vw, 0.875rem);
  --text-sm: clamp(0.875rem, 0.8rem + 0.375vw, 1rem);
  --text-base: clamp(1rem, 0.9rem + 0.5vw, 1.125rem);
  --text-lg: clamp(1.125rem, 1rem + 0.625vw, 1.25rem);
  --text-xl: clamp(1.25rem, 1rem + 1.25vw, 1.5rem);
  --text-2xl: clamp(1.5rem, 1.25rem + 1.25vw, 2rem);
  --text-3xl: clamp(1.875rem, 1.5rem + 1.875vw, 2.5rem);
  --text-4xl: clamp(2.25rem, 1.75rem + 2.5vw, 3.5rem);
}

/* Usage */
h1 { font-size: var(--text-4xl); }
h2 { font-size: var(--text-3xl); }
h3 { font-size: var(--text-2xl); }
p { font-size: var(--text-base); }

/* Fluid spacing scale */
:root {
  --space-xs: clamp(0.25rem, 0.2rem + 0.25vw, 0.5rem);
  --space-sm: clamp(0.5rem, 0.4rem + 0.5vw, 0.75rem);
  --space-md: clamp(1rem, 0.8rem + 1vw, 1.5rem);
  --space-lg: clamp(1.5rem, 1.2rem + 1.5vw, 2.5rem);
  --space-xl: clamp(2rem, 1.5rem + 2.5vw, 4rem);
}

// Utility function for fluid values
function fluidValue(minSize: number, maxSize: number, minWidth = 320, maxWidth = 1280) {
  const slope = (maxSize - minSize) / (maxWidth - minWidth);
  const yAxisIntersection = -minWidth * slope + minSize;

  return `clamp(${minSize}rem, ${yAxisIntersection.toFixed(4)}rem + ${(slope * 100).toFixed(4)}vw, ${maxSize}rem)`;
}

// Generate fluid type scale
const fluidTypeScale = {
  sm: fluidValue(0.875, 1),
  base: fluidValue(1, 1.125),
  lg: fluidValue(1.25, 1.5),
  xl: fluidValue(1.5, 2),
  '2xl': fluidValue(2, 3),
};

Pattern 3: CSS Grid Responsive Layout

/* Auto-fit grid - items wrap automatically */
.grid-auto {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(min(300px, 100%), 1fr));
  gap: 1.5rem;
}

/* Auto-fill grid - maintains empty columns */
.grid-auto-fill {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 1rem;
}

/* Responsive grid with named areas */
.page-layout {
  display: grid;
  grid-template-areas:
    "header"
    "main"
    "sidebar"
    "footer";
  gap: 1rem;
}

@media (min-width: 768px) {
  .page-layout {
    grid-template-columns: 1fr 300px;
    grid-template-areas:
      "header header"
      "main sidebar"
      "footer footer";
  }
}

@media (min-width: 1024px) {
  .page-layout {
    grid-template-columns: 250px 1fr 300px;
    grid-template-areas:
      "header header header"
      "nav main sidebar"
      "footer footer footer";
  }
}

.header { grid-area: header; }
.main { grid-area: main; }
.sidebar { grid-area: sidebar; }
.footer { grid-area: footer; }

// Responsive grid component
function ResponsiveGrid({
  children,
  minItemWidth = '250px',
  gap = '1.5rem',
}) {
  return (
    <div
      className="grid"
      style={{
        gridTemplateColumns: `repeat(auto-fit, minmax(min(${minItemWidth}, 100%), 1fr))`,
        gap,
      }}
    >
      {children}
    </div>
  );
}

// Usage with Tailwind
function ProductGrid({ products }) {
  return (
    <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 xl:grid-cols-4 gap-4 md:gap-6">
      {products.map((product) => (
        <ProductCard key={product.id} product={product} />
      ))}
    </div>
  );
}

Pattern 4: Responsive Navigation

function ResponsiveNav({ items }) {
  const [isOpen, setIsOpen] = useState(false);

  return (
    <nav className="relative">
      {/* Mobile menu button */}
      <button
        className="lg:hidden p-2"
        onClick={() => setIsOpen(!isOpen)}
        aria-expanded={isOpen}
        aria-controls="nav-menu"
      >
        <span className="sr-only">Toggle navigation</span>
        {isOpen ? <X /> : <Menu />}
      </button>

      {/* Navigation links */}
      <ul
        id="nav-menu"
        className={cn(
          // Base: hidden on mobile
          'absolute top-full left-0 right-0 bg-background border-b',
          'flex flex-col',
          // Mobile: slide down
          isOpen ? 'flex' : 'hidden',
          // Desktop: always visible, horizontal
          'lg:static lg:flex lg:flex-row lg:border-0 lg:bg-transparent'
        )}
      >
        {items.map((item) => (
          <li key={item.href}>
            <a
              href={item.href}
              className={cn(
                'block px-4 py-3',
                'lg:px-3 lg:py-2',
                'hover:bg-muted lg:hover:bg-transparent lg:hover:text-primary'
              )}
            >
              {item.label}
            </a>
          </li>
        ))}
      </ul>
    </nav>
  );
}

Pattern 5: Responsive Images

// Responsive image with art direction
function ResponsiveHero() {
  return (
    <picture>
      {/* Art direction: different crops for different screens */}
      <source
        media="(min-width: 1024px)"
        srcSet="/hero-wide.webp"
        type="image/webp"
      />
      <source
        media="(min-width: 768px)"
        srcSet="/hero-medium.webp"
        type="image/webp"
      />
      <source srcSet="/hero-mobile.webp" type="image/webp" />

      {/* Fallback */}
      <img
        src="/hero-mobile.jpg"
        alt="Hero image description"
        className="w-full h-auto"
        loading="eager"
        fetchpriority="high"
      />
    </picture>
  );
}

// Responsive image with srcset for resolution switching
function ProductImage({ product }) {
  return (
    <img
      src={product.image}
      srcSet={`
        ${product.image}?w=400 400w,
        ${product.image}?w=800 800w,
        ${product.image}?w=1200 1200w
      `}
      sizes="(max-width: 640px) 100vw, (max-width: 1024px) 50vw, 33vw"
      alt={product.name}
      className="w-full h-auto object-cover"
      loading="lazy"
    />
  );
}

Pattern 6: Responsive Tables

// Responsive table with horizontal scroll
function ResponsiveTable({ data, columns }) {
  return (
    <div className="w-full overflow-x-auto">
      <table className="w-full min-w-[600px]">
        <thead>
          <tr>
            {columns.map((col) => (
              <th key={col.key} className="text-left p-3">
                {col.label}
              </th>
            ))}
          </tr>
        </thead>
        <tbody>
          {data.map((row, i) => (
            <tr key={i} className="border-t">
              {columns.map((col) => (
                <td key={col.key} className="p-3">
                  {row[col.key]}
                </td>
              ))}
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
}

// Card-based table for mobile
function ResponsiveDataTable({ data, columns }) {
  return (
    <>
      {/* Desktop table */}
      <table className="hidden md:table w-full">
        {/* ... standard table */}
      </table>

      {/* Mobile cards */}
      <div className="md:hidden space-y-4">
        {data.map((row, i) => (
          <div key={i} className="border rounded-lg p-4 space-y-2">
            {columns.map((col) => (
              <div key={col.key} className="flex justify-between">
                <span className="font-medium text-muted-foreground">
                  {col.label}
                </span>
                <span>{row[col.key]}</span>
              </div>
            ))}
          </div>
        ))}
      </div>
    </>
  );
}

Viewport Units

/* Standard viewport units */
.full-height {
  height: 100vh; /* May cause issues on mobile */
}

/* Dynamic viewport units (recommended for mobile) */
.full-height-dynamic {
  height: 100dvh; /* Accounts for mobile browser UI */
}

/* Small viewport (minimum) */
.min-full-height {
  min-height: 100svh;
}

/* Large viewport (maximum) */
.max-full-height {
  max-height: 100lvh;
}

/* Viewport-relative font sizing */
.hero-title {
  /* 5vw with min/max bounds */
  font-size: clamp(2rem, 5vw, 4rem);
}

Best Practices

1. Mobile-First: Start with mobile styles, enhance for larger screens
2. Content Breakpoints: Set breakpoints based on content, not devices
3. Fluid Over Fixed: Use fluid values for typography and spacing
4. Container Queries: Use for component-level responsiveness
5. Test Real Devices: Simulators don't catch all issues
6. Performance: Optimize images, lazy load off-screen content
7. Touch Targets: Maintain 44x44px minimum on mobile
8. Logical Properties: Use inline/block for internationalization

Common Issues

• Horizontal Overflow: Content breaking out of viewport
• Fixed Widths: Using px instead of relative units
• Viewport Height: 100vh issues on mobile browsers
• Font Size: Text too small on mobile
• Touch Targets: Buttons too small to tap accurately
• Aspect Ratio: Images squishing or stretching
• Z-Index Stacking: Overlays breaking on different screens

Resources

• CSS Container Queries
• Utopia Fluid Type Calculator
• Every Layout
• Responsive Images Guide
• CSS Grid Garden