Responsive Web Design

Container Queries vs Media Queries

Default: Media queries for page layout (nav, sidebar). Container queries for reusable components that render in different contexts.

/* Container query setup */
.card-wrapper {
  container-type: inline-size;
  container-name: card;
}

@container card (min-width: 400px) {
  .card { flex-direction: row; }
  .card-image { width: 40%; }
}

@container card (max-width: 399px) {
  .card { flex-direction: column; }
  .card-image { width: 100%; }
}

Fluid Typography

/* clamp(min, preferred, max) — no breakpoints needed */
:root {
  --text-sm: clamp(0.8rem, 0.17vw + 0.76rem, 0.89rem);
  --text-base: clamp(1rem, 0.34vw + 0.91rem, 1.19rem);
  --text-lg: clamp(1.25rem, 0.61vw + 1.1rem, 1.58rem);
  --text-xl: clamp(1.56rem, 1vw + 1.31rem, 2.11rem);
  --text-2xl: clamp(1.95rem, 1.56vw + 1.56rem, 2.81rem);
  --text-3xl: clamp(2.44rem, 2.38vw + 1.85rem, 3.75rem);
}

h1 { font-size: var(--text-3xl); }
p { font-size: var(--text-base); }

Mobile-First Strategy

Base styles = mobile. Layer up with min-width breakpoints: 640px (sm), 1024px (md), 1280px (lg).

Responsive Images

Use srcset + sizes for resolution switching, <picture> + <source media> for art direction. Always loading="lazy" below fold.

CSS Grid Patterns

Use repeat(auto-fit, minmax(250px, 1fr)) for breakpoint-free responsive grids. Sidebar: fixed + minmax(0, 1fr) behind a media query.

Gotchas

• Viewport units on mobile: 100vh includes browser chrome; use 100dvh (dynamic viewport height) instead
• Container query support: Baseline 2023 -- add @supports (container-type: inline-size) fallback for older browsers
• Touch targets: Minimum 44x44px (WCAG 2.5.5); use min-height: 44px; min-width: 44px on interactive elements
• Horizontal scroll: Always test with overflow-x: hidden on body during dev to catch overflow; use max-width: 100% on images/videos
• Font loading shift: Use font-display: swap and size-adjust to minimize CLS from web font loading

Cross-References

• frontend:tailwind-design-system -- Tailwind responsive utilities, breakpoint config, container queries plugin
• frontend:accessibility-testing -- Touch target compliance, responsive WCAG requirements