mobile-first-design

name	mobile-first-design
description	Designs responsive interfaces starting from mobile screens with progressive enhancement for larger devices. Use when building responsive websites, optimizing for mobile users, or implementing adaptive layouts.
license	MIT

Mobile-First Design

Design interfaces starting with mobile as the foundation, then enhance for larger screens.

Breakpoints

Name	Width	Devices
Mobile	320-480px	iPhone SE, small Android
Tablet	481-768px	iPad mini
Desktop	769-1024px	iPad Pro, laptops
Large	1025px+	Desktop monitors

Mobile-First CSS

/* Base styles (mobile) */
.container {
  padding: 1rem;
}

.nav {
  display: none; /* Hidden on mobile */
}

.nav-toggle {
  display: block; /* Hamburger visible */
}

/* Tablet and up */
@media (min-width: 768px) {
  .container {
    padding: 2rem;
    max-width: 720px;
    margin: 0 auto;
  }

  .nav {
    display: flex;
  }

  .nav-toggle {
    display: none;
  }
}

/* Desktop */
@media (min-width: 1024px) {
  .container {
    max-width: 960px;
  }
}

Touch-Friendly Design

/* Minimum touch target: 48x48px */
.button {
  min-height: 48px;
  min-width: 48px;
  padding: 12px 24px;
}

/* Adequate spacing */
.list-item {
  padding: 16px;
  margin-bottom: 8px;
}

Performance Requirements

Metric	Target
First Contentful Paint	<3s on 3G
JS bundle	<100KB gzipped
Total page weight	<500KB

Progressive Enhancement

<!-- Layer 1: Semantic HTML (works without CSS/JS) -->
<nav>
  <a href="/home">Home</a>
  <a href="/about">About</a>
</nav>

<!-- Layer 2: CSS enhances appearance -->
<!-- Layer 3: JS adds interactivity -->

Best Practices

• Start design at 320px width
• Use relative units (rem, %, vw)
• Test on real devices
• Optimize images for mobile
• Minimize JavaScript for initial load
• Ensure readable text without zooming