responsive-design

SKILL.md

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

Mobile-First: Start with mobile styles, enhance for larger screens

Content Breakpoints: Set breakpoints based on content, not devices

Fluid Over Fixed: Use fluid values for typography and spacing

Container Queries: Use for component-level responsiveness

Test Real Devices: Simulators don't catch all issues

Performance: Optimize images, lazy load off-screen content

Touch Targets: Maintain 44x44px minimum on mobile

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