> **Additional context needed**: target platforms/devices and usage contexts.

Adapt an existing design to a different context: another screen size, device, platform, or use case. The trap is treating adaptation as scaling. The job is rethinking the experience for the new context.

**Web only** (mobile web included). Native platforms (`ios` / `android` / `adaptive`) route to [adapt.native.md](adapt.native.md) instead; if the project is native, switch to it now.

---

## Assess Adaptation Challenge

Understand what needs adaptation and why:

1. **Identify the source context**:
   - What was it designed for originally? (Desktop web? Mobile app?)
   - What assumptions were made? (Large screen? Mouse input? Fast connection?)
   - What works well in current context?

2. **Understand target context**:
   - **Device**: Mobile, tablet, desktop, TV, watch, print?
   - **Input method**: Touch, mouse, keyboard, voice, gamepad?
   - **Screen constraints**: Size, resolution, orientation?
   - **Connection**: Fast wifi, slow 3G, offline?
   - **Usage context**: On-the-go vs desk, quick glance vs focused reading?
   - **User expectations**: What do users expect on this platform?

3. **Identify adaptation challenges**:
   - What won't fit? (Content, navigation, features)
   - What won't work? (Hover states on touch, tiny touch targets)
   - What's inappropriate? (Desktop patterns on mobile, mobile patterns on desktop)

**CRITICAL**: Adaptation is rethinking the experience for the new context, not scaling pixels.

## Plan Adaptation Strategy

Create context-appropriate strategy:

### Mobile Adaptation (Desktop → Mobile)

**Layout Strategy**:
- Single column instead of multi-column
- Vertical stacking instead of side-by-side
- Full-width components instead of fixed widths
- Bottom navigation instead of top/side navigation

**Interaction Strategy**:
- Touch targets 44x44px minimum (not hover-dependent)
- Swipe gestures where appropriate (lists, carousels)
- Bottom sheets instead of dropdowns
- Thumbs-first design (controls within thumb reach)
- Larger tap areas with more spacing

**Content Strategy**:
- Progressive disclosure (don't show everything at once)
- Prioritize primary content (secondary content in tabs/accordions)
- Shorter text (more concise)
- Larger text (16px minimum)

**Navigation Strategy**:
- Hamburger menu or bottom navigation
- Reduce navigation complexity
- Sticky headers for context
- Back button in navigation flow

### Tablet Adaptation (Hybrid Approach)

**Layout Strategy**:
- Two-column layouts (not single or three-column)
- Side panels for secondary content
- Master-detail views (list + detail)
- Adaptive based on orientation (portrait vs landscape)

**Interaction Strategy**:
- Support both touch and pointer
- Touch targets 44x44px but allow denser layouts than phone
- Side navigation drawers
- Multi-column forms where appropriate

### Desktop Adaptation (Mobile → Desktop)

**Layout Strategy**:
- Multi-column layouts (use horizontal space)
- Side navigation always visible
- Multiple information panels simultaneously
- Fixed widths with max-width constraints (don't stretch to 4K)

**Interaction Strategy**:
- Hover states for additional information
- Keyboard shortcuts
- Right-click context menus
- Drag and drop where helpful
- Multi-select with Shift/Cmd

**Content Strategy**:
- Show more information upfront (less progressive disclosure)
- Data tables with many columns
- Richer visualizations
- More detailed descriptions

### Print Adaptation (Screen → Print)

**Layout Strategy**:
- Page breaks at logical points
- Remove navigation, footer, interactive elements
- Black and white (or limited color)
- Proper margins for binding

**Content Strategy**:
- Expand shortened content (show full URLs, hidden sections)
- Add page numbers, headers, footers
- Include metadata (print date, page title)
- Convert charts to print-friendly versions

### Email Adaptation (Web → Email)

**Layout Strategy**:
- Narrow width (600px max)
- Single column only
- Inline CSS (no external stylesheets)
- Table-based layouts (for email client compatibility)

**Interaction Strategy**:
- Large, obvious CTAs (buttons not text links)
- No hover states (not reliable)
- Deep links to web app for complex interactions

## Implement Adaptations

Apply changes systematically:

### Responsive Breakpoints

Choose appropriate breakpoints:
- Mobile: 320px-767px
- Tablet: 768px-1023px
- Desktop: 1024px+
- Or content-driven breakpoints (where design breaks)

### Layout Adaptation Techniques

- **CSS Grid/Flexbox**: Reflow layouts automatically
- **Container Queries**: Adapt based on container, not viewport
- **`clamp()`**: Fluid sizing between min and max
- **Media queries**: Different styles for different contexts
- **Display properties**: Show/hide elements per context

### Touch Adaptation

- Increase touch target sizes (44x44px minimum)
- Add more spacing between interactive elements
- Remove hover-dependent interactions
- Add touch feedback (ripples, highlights)
- Consider thumb zones (easier to reach bottom than top)

### Content Adaptation

- Use `display: none` sparingly (still downloads)
- Progressive enhancement (core content first, enhancements on larger screens)
- Lazy loading for off-screen content
- Responsive images (`srcset`, `picture` element)

### Navigation Adaptation

- Transform complex nav to hamburger/drawer on mobile
- Bottom nav bar for mobile apps
- Persistent side navigation on desktop
- Breadcrumbs on smaller screens for context

**IMPORTANT**: Test on real devices. Device emulation in DevTools is helpful but not perfect.

**NEVER**:
- Hide core functionality on mobile (if it matters, make it work)
- Assume desktop = powerful device (consider accessibility, older machines)
- Use different information architecture across contexts (confusing)
- Break user expectations for platform (mobile users expect mobile patterns)
- Forget landscape orientation on mobile/tablet
- Use generic breakpoints blindly (use content-driven breakpoints)
- Ignore touch on desktop (many desktop devices have touch)

## Verify Adaptations

Test thoroughly across contexts:

- **Real devices**: Test on actual phones, tablets, desktops
- **Different orientations**: Portrait and landscape
- **Different browsers**: Safari, Chrome, Firefox, Edge
- **Different OS**: iOS, Android, Windows, macOS
- **Different input methods**: Touch, mouse, keyboard
- **Edge cases**: Very small screens (320px), very large screens (4K)
- **Slow connections**: Test on throttled network

When the adaptation feels native to each context, hand off to `/impeccable polish` for the final pass.

---

## Reference Material

The sections below were previously `responsive-design.md` and live inline now so the adapt flow has its deep responsive reference in one place.

### Responsive Design

#### Mobile-First: Write It Right

Start with base styles for mobile, use `min-width` queries to layer complexity. Desktop-first (`max-width`) means mobile loads unnecessary styles first.

#### Breakpoints: Content-Driven

Don't chase device sizes; let content tell you where to break. Start narrow, stretch until design breaks, add breakpoint there. Three breakpoints usually suffice (640, 768, 1024px). Use `clamp()` for fluid values without breakpoints.

#### Detect Input Method, Not Just Screen Size

**Screen size doesn't tell you input method.** A laptop with touchscreen, a tablet with keyboard. Use pointer and hover queries:

```css
/* Fine pointer (mouse, trackpad) */
@media (pointer: fine) {
  .button { padding: 8px 16px; }
}

/* Coarse pointer (touch, stylus) */
@media (pointer: coarse) {
  .button { padding: 12px 20px; }  /* Larger touch target */
}

/* Device supports hover */
@media (hover: hover) {
  .card:hover { transform: translateY(-2px); }
}

/* Device doesn't support hover (touch) */
@media (hover: none) {
  .card { /* No hover state - use active instead */ }
}
```

**Critical**: Don't rely on hover for functionality. Touch users can't hover.

#### Safe Areas: Handle the Notch

Modern phones have notches, rounded corners, and home indicators. Use `env()`:

```css
body {
  padding-top: env(safe-area-inset-top);
  padding-bottom: env(safe-area-inset-bottom);
  padding-left: env(safe-area-inset-left);
  padding-right: env(safe-area-inset-right);
}

/* With fallback */
.footer {
  padding-bottom: max(1rem, env(safe-area-inset-bottom));
}
```

**Enable viewport-fit** in your meta tag:
```html
<meta name="viewport" content="width=device-width, initial-scale=1, viewport-fit=cover">
```

#### Responsive Images: Get It Right

##### srcset with Width Descriptors

```html
<img
  src="hero-800.jpg"
  srcset="
    hero-400.jpg 400w,
    hero-800.jpg 800w,
    hero-1200.jpg 1200w
  "
  sizes="(max-width: 768px) 100vw, 50vw"
  alt="Hero image"
>
```

**How it works**:
- `srcset` lists available images with their actual widths (`w` descriptors)
- `sizes` tells the browser how wide the image will display
- Browser picks the best file based on viewport width AND device pixel ratio

##### Picture Element for Art Direction

When you need different crops/compositions (not just resolutions):

```html
<picture>
  <source media="(min-width: 768px)" srcset="wide.jpg">
  <source media="(max-width: 767px)" srcset="tall.jpg">
  <img src="fallback.jpg" alt="...">
</picture>
```

#### Layout Adaptation Patterns

**Navigation**: Three stages: hamburger + drawer on mobile, horizontal compact on tablet, full with labels on desktop. **Tables**: Transform to cards on mobile using `display: block` and `data-label` attributes. **Progressive disclosure**: Use `<details>/<summary>` for content that can collapse on mobile.

#### Testing: Don't Trust DevTools Alone

DevTools device emulation is useful for layout but misses:

- Actual touch interactions
- Real CPU/memory constraints
- Network latency patterns
- Font rendering differences
- Browser chrome/keyboard appearances

**Test on at least**: One real iPhone, one real Android, a tablet if relevant. Cheap Android phones reveal performance issues you'll never see on simulators.

---

**Avoid**: Desktop-first design. Device detection instead of feature detection. Separate mobile/desktop codebases. Ignoring tablet and landscape. Assuming all mobile devices are powerful.
