### iOS Design Guidelines

**Design Principles:**
- Clarity, deference, depth
- Direct manipulation
- Semantic use of color

**UI Elements:** Navigation bars, tab bars, toolbars, action sheets, alerts

**Typography:** San Francisco font family, Dynamic Type support

**Gestures:** Tap, swipe, pinch, rotate, long press

### Android Material Design

**Design Principles:**
- Material as metaphor
- Bold, graphic, intentional
- Motion provides meaning

**UI Elements:** App bars, bottom navigation, FABs, drawers, snackbars

**Typography:** Roboto font family, type scale

**Elevation:** z-axis positioning, shadows indicate hierarchy

### Mobile UI Patterns

- **Onboarding**: Welcome screens, feature tours, permission requests
- **Authentication**: Social login, biometric, magic links
- **Navigation**: Tab bars, drawers, stack navigation
- **Forms**: Input optimization, keyboard types, validation
- **Lists and Grids**: Swipe actions, pull-to-refresh
- **Search**: Prominent search bar, recent searches, filters
- **Notifications**: In-app badges, push notifications, banners

### Touch Targets

- **Minimum Size**: 44x44pt (iOS), 48x48dp (Android)
- **Spacing**: 8dp minimum between targets
- **Thumb Zone**: Most accessible area for single-handed use (bottom center)

---