Agent Skills: Responsive Web Design

Responsive Web Design

Overview

Build mobile-first responsive interfaces using modern CSS techniques including Flexbox, Grid, and media queries to create adaptable user experiences.

When to Use

• Multi-device applications
• Mobile-first development
• Accessible layouts
• Flexible UI systems
• Cross-browser compatibility

Implementation Examples

1. Mobile-First Media Query Strategy

/* Mobile styles (default) */
.container {
  display: flex;
  flex-direction: column;
  padding: 16px;
  gap: 16px;
}

.card {
  padding: 16px;
  border-radius: 8px;
  background: white;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 16px;
}

/* Tablet (640px and up) */
@media (min-width: 640px) {
  .container {
    flex-direction: row;
    padding: 24px;
  }

  .grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .card {
    padding: 24px;
  }
}

/* Desktop (1024px and up) */
@media (min-width: 1024px) {
  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 32px;
  }

  .grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .card {
    padding: 32px;
  }
}

/* Large Desktop (1280px and up) */
@media (min-width: 1280px) {
  .container {
    max-width: 1400px;
  }

  .grid {
    grid-template-columns: repeat(4, 1fr);
    gap: 24px;
  }
}

2. Flexbox Responsive Navigation

<!-- HTML -->
<nav class="navbar">
  <div class="navbar-brand">Logo</div>
  <button class="navbar-toggle" id="menuToggle">Menu</button>
  <ul class="navbar-menu" id="navMenu">
    <li><a href="#home">Home</a></li>
    <li><a href="#about">About</a></li>
    <li><a href="#services">Services</a></li>
    <li><a href="#contact">Contact</a></li>
  </ul>
</nav>

<style>
  .navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 16px;
    background-color: #333;
    color: white;
  }

  .navbar-brand {
    font-size: 24px;
    font-weight: bold;
  }

  .navbar-toggle {
    display: block;
    background: none;
    border: none;
    color: white;
    cursor: pointer;
    font-size: 24px;
  }

  .navbar-menu {
    display: none;
    list-style: none;
    flex-direction: column;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background-color: #222;
    padding: 16px;
    gap: 8px;
  }

  .navbar-menu.active {
    display: flex;
  }

  @media (min-width: 768px) {
    .navbar-toggle {
      display: none;
    }

    .navbar-menu {
      display: flex;
      flex-direction: row;
      position: static;
      background-color: transparent;
      padding: 0;
      gap: 32px;
    }
  }

  .navbar-menu a {
    color: white;
    text-decoration: none;
  }
</style>

3. CSS Grid Responsive Layout

/* 12-column grid system */
.grid-container {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
  gap: 16px;
  padding: 16px;
}

.grid-item {
  grid-column: span 12;
  padding: 16px;
  background: white;
  border-radius: 8px;
  border: 1px solid #e0e0e0;
}

/* Mobile: stacked */
.header {
  grid-column: span 12;
}
.sidebar {
  grid-column: span 12;
}
.main {
  grid-column: span 12;
}
.footer {
  grid-column: span 12;
}

/* Tablet: 2-column layout */
@media (min-width: 768px) {
  .header {
    grid-column: span 12;
  }
  .sidebar {
    grid-column: span 3;
  }
  .main {
    grid-column: span 9;
  }
  .footer {
    grid-column: span 12;
  }
}

/* Desktop: 3-column with sidebar */
@media (min-width: 1024px) {
  .header {
    grid-column: span 12;
  }
  .sidebar {
    grid-column: span 2;
  }
  .main {
    grid-column: span 8;
  }
  .aside {
    grid-column: span 2;
  }
  .footer {
    grid-column: span 12;
  }
}

4. Responsive Typography

/* Fluid typography */
html {
  font-size: 16px;
}

h1 {
  font-size: clamp(24px, 8vw, 48px);
  line-height: 1.2;
}

h2 {
  font-size: clamp(20px, 5vw, 36px);
  line-height: 1.3;
}

p {
  font-size: clamp(14px, 2vw, 18px);
  line-height: 1.6;
  max-width: 65ch;
}

/* Responsive spacing */
.container {
  padding: clamp(16px, 5vw, 48px);
  margin-left: auto;
  margin-right: auto;
  width: 90%;
  max-width: 1200px;
}

/* Responsive images */
img {
  max-width: 100%;
  height: auto;
  display: block;
}

picture {
  display: block;
}

5. Responsive Cards Component

<div class="card-grid">
  <div class="card">
    <img src="image.jpg" alt="Card image" class="card-image" />
    <div class="card-content">
      <h3>Card Title</h3>
      <p>Card description goes here</p>
      <a href="#" class="card-link">Learn More</a>
    </div>
  </div>
</div>

<style>
  .card-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: 16px;
    padding: 16px;
  }

  @media (min-width: 640px) {
    .card-grid {
      grid-template-columns: repeat(2, 1fr);
      gap: 20px;
      padding: 20px;
    }
  }

  @media (min-width: 1024px) {
    .card-grid {
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      padding: 24px;
    }
  }

  .card {
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    transition:
      transform 0.2s,
      box-shadow 0.2s;
  }

  .card:hover {
    transform: translateY(-4px);
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
  }

  .card-image {
    width: 100%;
    height: auto;
    aspect-ratio: 16/9;
    object-fit: cover;
  }

  .card-content {
    padding: 16px;
  }

  .card-content h3 {
    margin: 0 0 8px;
    font-size: 18px;
  }

  .card-content p {
    margin: 0 0 12px;
    color: #666;
    font-size: 14px;
  }

  .card-link {
    display: inline-block;
    color: #0066cc;
    text-decoration: none;
    font-weight: 500;
  }
</style>

Best Practices

• Start with mobile-first approach
• Use flexible units (%, em, rem)
• Implement CSS Grid and Flexbox
• Test on real devices
• Optimize images with srcset
• Use CSS media queries strategically
• Consider touch targets on mobile
• Provide readable text sizes
• Test accessibility at all sizes

Resources

• MDN CSS Media Queries
• CSS Flexbox Guide
• CSS Grid Guide
• Google Mobile-Friendly Test