SKILL.md
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
