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+# PRD: Design System Implementation
+
+**Flight Radar Web Interface — Visual Redesign**
+
+| | |
+|---|---|
+| **Version** | 1.0 |
+| **Status** | Ready for Implementation |
+| **Date** | February 2026 |
+| **Design reference** | `docs/DESIGN_SYSTEM.md` |
+| **Target** | Claude Code Implementation |
+
+---
+
+## 1. Overview
+
+The Flight Radar web interface was built as a functional prototype. It works correctly but has no visual design system: navigation links run together into an unreadable string, stat cards are unstyled white boxes, forms lack any grouping or hierarchy, and the application is unusable on mobile devices.
+
+This PRD specifies the complete implementation of the Material Design 3–inspired design system defined in `docs/DESIGN_SYSTEM.md`. The result must be a production-quality UI that a non-technical user would consider polished and trustworthy.
+
+**No new features are added in this PRD.** Every existing function is preserved. This is a pure UI/UX replacement.
+
+---
+
+## 2. Goals
+
+- Implement the full design token system (colours, typography, spacing, elevation) from `docs/DESIGN_SYSTEM.md §3–§6`
+- Replace the broken top navigation with a proper sidebar on desktop and a bottom navigation bar on mobile
+- Redesign all 5 pages using the component specifications in `docs/DESIGN_SYSTEM.md §7–§8`
+- Build a reusable component library that makes future pages easy to build consistently
+- Achieve a fully functional, accessible mobile experience at 375px viewport width
+- Pass a manual accessibility review: keyboard navigation, colour contrast (WCAG AA), and focus management
+
+## 3. Non-Goals
+
+- No new API endpoints or backend changes
+- No dark mode (design tokens must be structured to support it later, but it need not be active)
+- No animations that require a JS animation library (CSS transitions only)
+- No redesign of the `AirportSearch` dropdown's behaviour — only its visual styling
+- No changes to `api.ts`, `App.tsx`, routing, or any Python backend file
+- No new pages beyond the existing 5
+
+---
+
+## 4. Success Criteria
+
+| Criterion | Measure |
+|-----------|---------|
+| Navigation is readable | Nav items are separated, active state is visually distinct, works on 375px |
+| Stats are scannable | Each stat card has an icon, colour accent, and label — no two look identical |
+| Scan list is parseable | Destination, status chip, date range, and flight count are each in distinct visual zones |
+| Form feels structured | Field groups are visually separated, labels float on focus, help text is present |
+| Empty states have actions | Every zero-data view has an illustration, headline, and a CTA button |
+| Loading has feedback | Every async wait shows a skeleton or spinner — never a blank area |
+| Mobile is functional | All 5 pages are usable at 375px — no horizontal overflow, no overlapping elements |
+| Accessibility baseline | All interactive elements ≥ 44×44px, focus rings visible, colour not sole differentiator |
+
+---
+
+## 5. Constraints
+
+- **Tech stack is fixed:** React 19, TypeScript strict mode, Tailwind CSS v4, Vite 7
+- **No CSS-in-JS:** all styling via Tailwind utility classes + custom CSS variables in `index.css`
+- **Tailwind v4 `@theme` syntax:** token definitions use `@theme { }` block, not `tailwind.config.js`
+- **Type-only imports:** `import type { X }` required for all interface/type imports (TypeScript strict)
+- **No jQuery, no Bootstrap, no external UI framework** (MUI, Chakra, Ant Design etc.)
+- **Three allowed new dependencies:** `lucide-react`, `clsx`, `tailwind-merge`
+
+---
+
+## 6. Implementation Phases
+
+The work is divided into 5 phases that must be executed in order, because each phase depends on the previous one. A phase is complete only when all its acceptance criteria pass.
+
+---
+
+### Phase 1 — Foundation (tokens, fonts, layout shell)
+
+**Objective:** Every page already looks better before a single page component is touched, because the global tokens and navigation are correct.
+
+#### 1.1 Design tokens
+
+**File:** `frontend/src/index.css`
+
+Replace the existing 3-line Tailwind import with:
+
+```css
+@import "tailwindcss";
+
+@theme {
+  /* Brand colours */
+  --color-primary: #1A73E8;
+  --color-primary-container: #D2E3FC;
+  --color-on-primary: #FFFFFF;
+  --color-on-primary-container: #003E8C;
+  --color-secondary: #0F9D58;
+  --color-secondary-container: #C8E6C9;
+  --color-on-secondary: #FFFFFF;
+  --color-on-secondary-container: #00391A;
+  --color-tertiary: #F4B400;
+  --color-tertiary-container: #FFF0C0;
+  --color-on-tertiary: #3B2A00;
+  --color-error: #D93025;
+  --color-error-container: #FDECEA;
+  --color-on-error: #FFFFFF;
+
+  /* Surface roles */
+  --color-bg: #F8F9FA;
+  --color-surface: #FFFFFF;
+  --color-surface-2: #F1F3F4;
+  --color-surface-variant: #E8EAED;
+  --color-on-surface: #202124;
+  --color-on-surface-variant: #5F6368;
+  --color-outline: #DADCE0;
+  --color-outline-variant: #F1F3F4;
+
+  /* Semantic status colours (used via CSS variables, not Tailwind classes) */
+  --color-status-completed-bg: #E6F4EA;
+  --color-status-completed-text: #137333;
+  --color-status-completed-border: #A8D5B5;
+  --color-status-running-bg: #E8F0FE;
+  --color-status-running-text: #1557B0;
+  --color-status-running-border: #A8C7FA;
+  --color-status-pending-bg: #FEF7E0;
+  --color-status-pending-text: #7A5200;
+  --color-status-pending-border: #F9D659;
+  --color-status-failed-bg: #FDECEA;
+  --color-status-failed-text: #A50E0E;
+  --color-status-failed-border: #F5C6C6;
+
+  /* Shape */
+  --radius-xs: 4px;
+  --radius-sm: 8px;
+  --radius-md: 12px;
+  --radius-lg: 16px;
+  --radius-xl: 20px;
+  --radius-full: 9999px;
+
+  /* Typography */
+  --font-sans: 'Google Sans', 'Roboto', system-ui, -apple-system, sans-serif;
+  --font-mono: 'Roboto Mono', 'JetBrains Mono', ui-monospace, monospace;
+
+  /* Elevation shadows */
+  --shadow-1: 0 1px 2px rgba(0,0,0,.08);
+  --shadow-2: 0 2px 6px rgba(0,0,0,.10);
+  --shadow-3: 0 4px 12px rgba(0,0,0,.12);
+}
+
+/* Base resets */
+body {
+  background-color: var(--color-bg);
+  color: var(--color-on-surface);
+  font-family: var(--font-sans);
+  -webkit-font-smoothing: antialiased;
+}
+
+/* Skeleton shimmer */
+@keyframes shimmer {
+  0%   { background-position: -200% 0; }
+  100% { background-position: 200% 0; }
+}
+.skeleton {
+  background: linear-gradient(90deg, #E8EAED 25%, #F1F3F4 50%, #E8EAED 75%);
+  background-size: 200% 100%;
+  animation: shimmer 1.5s infinite;
+}
+
+/* Slide-up toast animation (keep existing) */
+@keyframes slide-up {
+  from { transform: translateY(100%); opacity: 0; }
+  to   { transform: translateY(0);    opacity: 1; }
+}
+.animate-slide-up { animation: slide-up 0.3s ease-out; }
+
+/* Spin for loading icons */
+@keyframes spin {
+  to { transform: rotate(360deg); }
+}
+.animate-spin-slow { animation: spin 0.6s linear infinite; }
+
+/* Reduced motion */
+@media (prefers-reduced-motion: reduce) {
+  *, *::before, *::after {
+    animation-duration: 0.01ms !important;
+    transition-duration: 0.01ms !important;
+  }
+}
+```
+
+#### 1.2 Google Fonts
+
+**File:** `frontend/index.html`
+
+Add inside `<head>`:
+
+```html
+<link rel="preconnect" href="https://fonts.googleapis.com">
+<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
+<link href="https://fonts.googleapis.com/css2?family=Google+Sans:wght@300;400;500&family=Roboto+Mono:wght@400&display=swap" rel="stylesheet">
+```
+
+#### 1.3 New dependencies
+
+```bash
+npm install lucide-react clsx tailwind-merge
+```
+
+#### 1.4 Layout shell redesign
+
+**File:** `frontend/src/components/Layout.tsx`
+
+Full replacement. The new layout has two distinct structures based on viewport:
+
+**Desktop (≥ 1024px):**
+```
+┌──────────┬──────────────────────────────────────────┐
+│ Sidebar  │ Top bar (64px)                           │
+│ (256px)  ├──────────────────────────────────────────┤
+│          │                                          │
+│  Logo    │  <Outlet /> wrapped in                   │
+│  Nav     │  max-w-5xl, px-6, py-8                  │
+│          │                                          │
+└──────────┴──────────────────────────────────────────┘
+```
+
+**Mobile (< 1024px):**
+```
+┌──────────────────────────────────────────────────┐
+│ Top bar (56px): logo + page title                │
+├──────────────────────────────────────────────────┤
+│                                                  │
+│  <Outlet /> px-4 py-4, pb-24 (room for nav)     │
+│                                                  │
+├──────────────────────────────────────────────────┤
+│ Bottom nav bar (56px + safe-area-bottom)         │
+└──────────────────────────────────────────────────┘
+```
+
+**Sidebar nav item spec:**
+- Height: 48px, padding: 0 16px, border-radius: 28px (full bleed within sidebar)
+- Active: `bg-primary-container text-on-primary-container font-medium`
+- Inactive: `text-on-surface-variant hover:bg-surface-2`
+- Icon: 20px Lucide icon, left-aligned, `mr-3`
+- The active pill is the full row width minus 12px horizontal margin on each side
+
+**Bottom nav item spec:**
+- 4 items equally spaced
+- Active: icon in Primary colour, 32×16px Primary Container pill behind icon, label in Primary
+- Inactive: icon + label in `on-surface-variant`
+- Label: 12px, 500 weight
+
+**Nav items and routes:**
+```
+Icon              Label       Route
+LayoutDashboard   Dashboard   /
+ScanSearch        Scans       /scans
+MapPin            Airports    /airports
+ScrollText        Logs        /logs
+```
+
+**Top bar (desktop):**
+- Height: 64px, `bg-surface border-b border-outline shadow-1`
+- Left: empty (sidebar is present)
+- Center/Left: current page title via `useLocation()` lookup
+- Right: `+ New Scan` filled button (navigates to `/scans`), hidden on `/scans` page itself
+
+**Top bar (mobile):**
+- Height: 56px
+- Left: ✈ `PlaneTakeoff` icon (20px, Primary) + "Flight Radar" text (title-lg)
+- Right: `+ New Scan` icon button (`Plus` icon, 40×40px) on dashboard only
+
+**Phase 1 acceptance criteria:**
+- [ ] Sidebar is visible on desktop, hidden on mobile
+- [ ] Bottom nav is visible on mobile, hidden on desktop
+- [ ] Active nav item is visually distinct from inactive
+- [ ] No horizontal scrollbar at any viewport width ≥ 320px
+- [ ] Google Sans font is loading and applied
+- [ ] `bg-primary` Tailwind class resolves to `#1A73E8`
+
+---
+
+### Phase 2 — Shared Component Library
+
+**Objective:** Create all reusable components before touching any page. Pages are then assembled from these building blocks.
+
+All new component files live in `frontend/src/components/`.
+
+#### 2.1 `Button.tsx`
+
+Props: `variant: 'filled' | 'outlined' | 'text' | 'icon'`, `size: 'sm' | 'md'` (default `md`), `loading?: boolean`, `icon?: LucideIcon`, `iconPosition?: 'left' | 'right'`, `disabled?`, `onClick?`, `type?`, `className?`, `children`
+
+Spec per variant — see `docs/DESIGN_SYSTEM.md §7.2`.
+
+The `loading` prop replaces children with a 16px spinner icon; button width is preserved via `min-w` matching the expected label width.
+
+#### 2.2 `StatusChip.tsx`
+
+Props: `status: 'completed' | 'running' | 'pending' | 'failed'`
+
+Spec: `docs/DESIGN_SYSTEM.md §7.3`.
+
+The chip reads its colours directly from the CSS variables `--color-status-{status}-bg` etc., applied inline or via a class map. The `running` status dot pulses using a CSS animation class.
+
+Icon mapping:
+```
+completed  →  CheckCircle2 (16px)
+running    →  Loader2 (16px, animate-spin-slow)
+pending    →  Clock (16px)
+failed     →  XCircle (16px)
+```
+
+#### 2.3 `StatCard.tsx`
+
+Props: `label: string`, `value: number | string`, `icon: LucideIcon`, `variant: 'default' | 'primary' | 'secondary' | 'tertiary' | 'error'`, `trend?: string`
+
+Spec: `docs/DESIGN_SYSTEM.md §7.4`.
+
+Icon circle size: 40×40px. Colours per variant:
+```
+default    #E8F0FE bg, Primary icon
+primary    #E8F0FE bg, Primary icon
+secondary  #E6F4EA bg, Secondary icon
+tertiary   #FEF7E0 bg, Tertiary icon
+error      #FDECEA bg, Error icon
+```
+
+Value typography: 28px (headline-md), 400 weight, `text-on-surface`.
+
+#### 2.4 `EmptyState.tsx`
+
+Props: `icon: LucideIcon`, `title: string`, `description?: string`, `action?: { label: string; onClick: () => void }`
+
+Layout: centred column, icon at 64px in a 96×96px circle with `bg-surface-2`, headline-sm title, body-md description in `text-on-surface-variant`, optional filled primary button.
+
+#### 2.5 `SkeletonCard.tsx`
+
+Props: `rows?: number` (default 3), `showHeader?: boolean`
+
+Renders an animated shimmer card placeholder. Uses the `.skeleton` CSS class from Phase 1.
+
+Variants to export separately:
+- `<SkeletonStatCard />` — matches StatCard dimensions
+- `<SkeletonListItem />` — matches the scan list card height (72px)
+- `<SkeletonTableRow />` — matches a table row (52px)
+
+#### 2.6 `SegmentedButton.tsx`
+
+Props: `options: Array<{ value: string; label: string; icon?: LucideIcon }>`, `value: string`, `onChange: (value: string) => void`
+
+Spec: `docs/DESIGN_SYSTEM.md §7.7`.
+
+The active segment shows a `Check` icon (16px) that slides in from the left using a CSS opacity+translate transition.
+
+#### 2.7 `AirportChip.tsx`
+
+Props: `code: string`, `onRemove: () => void`
+
+Spec: `docs/DESIGN_SYSTEM.md §7.8`.
+
+Shows a `PlaneTakeoff` icon (14px) before the code. The `×` button uses an `X` Lucide icon.
+
+#### 2.8 `Toast.tsx` (update existing)
+
+The existing `Toast.tsx` already handles dismissal logic. Update **only** the visual styling to match `docs/DESIGN_SYSTEM.md §7.12`.
+
+Changes needed:
+- New width (360px desktop / full-width mobile), border-radius 12px, shadow-3
+- Position: bottom-right on desktop (`fixed bottom-6 right-6`), bottom-center on mobile
+- Four variants: `success`, `error`, `info`, `warning` — each with distinct icon and colour per the design spec
+- Keep the existing `animate-slide-up` class
+
+**Phase 2 acceptance criteria:**
+- [ ] All 8 components render without TypeScript errors (`npm run build` passes)
+- [ ] `StatusChip` shows correct colour and icon for all 4 statuses
+- [ ] `SkeletonCard` shimmers
+- [ ] `SegmentedButton` check icon appears on the active segment
+- [ ] `Button` loading state preserves button width
+
+---
+
+### Phase 3 — Dashboard page
+
+**File:** `frontend/src/pages/Dashboard.tsx`
+
+**Objective:** Replace the current text-dump dashboard with a stats + card-list layout using Phase 2 components.
+
+#### 3.1 Loading state
+
+While `loading === true`, render:
+- 5× `<SkeletonStatCard />` in the stats grid
+- 5× `<SkeletonListItem />` in the recent scans section
+
+Do **not** show a spinner or "Loading…" text.
+
+#### 3.2 Stats grid
+
+Replace the 5 plain white boxes with `<StatCard>` components:
+
+```
+<StatCard label="Total Scans"  value={stats.total}     icon={ScanSearch}       variant="primary"   />
+<StatCard label="Pending"      value={stats.pending}   icon={Clock}            variant="tertiary"  />
+<StatCard label="Running"      value={stats.running}   icon={Loader2}          variant="primary"   />
+<StatCard label="Completed"    value={stats.completed} icon={CheckCircle2}     variant="secondary" />
+<StatCard label="Failed"       value={stats.failed}    icon={XCircle}          variant="error"     />
+```
+
+Grid: `grid-cols-2 sm:grid-cols-3 lg:grid-cols-5 gap-4`
+
+#### 3.3 Recent scans section
+
+Header row: `"Recent Scans"` (title-lg, `text-on-surface`) + `"View all →"` text button (right-aligned, links to a future full scan list — for now it links to `/scans`).
+
+Each scan renders as a card (not a `<tr>`). Card structure:
+
+```
+┌──────────────────────────────────────────────────────┐
+│  BDS → FMM, DUS                   ● completed  →    │
+│  26 Feb 2026 – 27 May 2026 · 1 adult · Economy      │
+│  182 routes · 50 flights found                       │
+└──────────────────────────────────────────────────────┘
+```
+
+- Arrow `→` (`ArrowRight`, 16px, `text-on-surface-variant`) right-aligned
+- On hover: card lifts (`shadow-2`, `translateY(-2px)`) via CSS transition 150ms
+- `<Link>` wraps the entire card (no nested interactive elements inside except the chip)
+- Date string: `formatDate` replaced with a relative label where applicable (e.g. "Today", "Yesterday", or absolute date)
+
+#### 3.4 Empty state
+
+When `scans.length === 0`:
+```
+<EmptyState
+  icon={ScanSearch}
+  title="No scans yet"
+  description="Create your first scan to discover flight routes and prices."
+  action={{ label: "+ New Scan", onClick: () => navigate('/scans') }}
+/>
+```
+
+**Phase 3 acceptance criteria:**
+- [ ] Skeleton shows while loading, disappears when data arrives
+- [ ] Each of 5 stat cards has a distinct icon and colour accent
+- [ ] Scan cards are separated, hoverable, and fully clickable
+- [ ] Status chip is visually separate from destination text (no more `"FMM,DUScompleted"`)
+- [ ] Empty state renders with button when no scans exist
+
+---
+
+### Phase 4 — Create Scan form
+
+**File:** `frontend/src/pages/Scans.tsx`
+
+**Objective:** Transform the flat HTML form into a structured, guided form with clear visual grouping.
+
+#### 4.1 Page structure
+
+```
+"New Scan" (headline-md)                           [← Cancel — text button]
+
+┌ Section: Origin ─────────────────────────────────┐
+│  Origin Airport                                   │
+│  [AirportSearch input — full width]              │
+│  Help text: "3-letter IATA code (e.g. BDS)"     │
+└───────────────────────────────────────────────────┘
+
+┌ Section: Destination ────────────────────────────┐
+│  [ 🌍 By Country | ✈ By Airports ]  ← SegmentedButton │
+│                                                   │
+│  [Country input — if country mode]                │
+│  [AirportSearch + AirportChip list — if airports] │
+└───────────────────────────────────────────────────┘
+
+┌ Section: Parameters ─────────────────────────────┐
+│  [Search Window]    [Seat Class]                  │
+│  [Adults]                                        │
+└───────────────────────────────────────────────────┘
+
+                          [Create Scan — filled button]
+```
+
+Each `┌ Section ┐` is a `bg-surface rounded-lg shadow-1 p-6` card with a section label in `label-sm uppercase text-on-surface-variant tracking-wider mb-4`.
+
+#### 4.2 Destination mode toggle
+
+Replace the two `<button>` elements with `<SegmentedButton>`:
+```tsx
+<SegmentedButton
+  options={[
+    { value: 'country', label: 'By Country', icon: Globe },
+    { value: 'airports', label: 'By Airports', icon: PlaneTakeoff },
+  ]}
+  value={destinationMode}
+  onChange={(v) => setDestinationMode(v as 'country' | 'airports')}
+/>
+```
+
+#### 4.3 Input styling
+
+All `<input>` and `<select>` elements adopt the outlined input style:
+- Border: `border border-outline rounded-xs` (4px corners)
+- Focus: `focus:border-primary focus:ring-2 focus:ring-primary focus:ring-offset-0 outline-none`
+- Height: 48px (slightly shorter than the 56px MD3 spec to suit a dense form)
+- Label: above the field, `label-md` weight, `text-on-surface-variant`
+- Helper text: `body-sm text-on-surface-variant mt-1`
+
+The `AirportSearch` component's internal input receives the same classes.
+
+#### 4.4 Airport chips
+
+Selected airports in airports mode use `<AirportChip>` (Phase 2 §2.7), wrapped in `flex flex-wrap gap-2 mt-3`.
+
+#### 4.5 Parameters section layout
+
+Desktop: `grid grid-cols-2 gap-4` for Window + Seat Class. Adults below, full width.
+Mobile: single column.
+
+#### 4.6 Number inputs
+
+`window_months` and `adults` inputs: hide browser spin buttons via CSS (`[appearance:textfield] [&::-webkit-inner-spin-button]:appearance-none`). Add manual `−` and `+` icon buttons (24px, ghost) flanking the value display.
+
+#### 4.7 Validation feedback
+
+Remove the inline error banner `div`. Instead:
+- Field-level errors render as `body-sm text-error mt-1` below the relevant input
+- The input border turns `border-error` on error
+- On submission failure from the API, show a `Toast` (error variant) instead of a banner
+
+#### 4.8 Submit / cancel
+
+Remove the `window.location.href = '/'` navigation. Use React Router `useNavigate()` instead.
+
+On success: show a `Toast` (success variant) then `navigate('/')` after 1500ms.
+
+**Phase 4 acceptance criteria:**
+- [ ] Three distinct visual sections (Origin, Destination, Parameters)
+- [ ] Segmented button replaces mode toggle buttons
+- [ ] Airport chips appear and are removable
+- [ ] Number inputs have manual increment/decrement buttons
+- [ ] Validation errors appear inline below the relevant field
+- [ ] Success navigates via React Router (not `window.location.href`)
+
+---
+
+### Phase 5 — Scan Details page
+
+**File:** `frontend/src/pages/ScanDetails.tsx`
+
+**Objective:** Replace the plain details layout with a header card, redesigned stats, animated expandable table rows, and a proper progress indicator.
+
+#### 5.1 Breadcrumb
+
+Replace the bare `← Back to Dashboard` link with:
+```
+← Dashboard / Scan #54
+```
+Use `ArrowLeft` (16px) icon. Style as `body-md text-on-surface-variant hover:text-on-surface`.
+
+#### 5.2 Header card
+
+A single `bg-surface shadow-1 rounded-lg p-6 mb-6` card containing:
+
+```
+Row 1: "BDS → FMM, DUS"  (headline-md, with PlaneTakeoff icon before text)
+        [right-aligned]: <StatusChip status={scan.status} />
+
+Row 2: Calendar icon · "26 Feb – 27 May 2026"
+        Users icon    · "1 adult"
+        Armchair icon · "Economy"
+        (all body-md, text-on-surface-variant, flex row with gap-4)
+
+Row 3 (if completed/failed):
+        Clock icon · Created at timestamp (body-sm, text-on-surface-variant)
+```
+
+#### 5.3 Stats row
+
+Replace the 3 plain cards with `<StatCard>` components. Loading state uses `<SkeletonStatCard />`.
+
+```
+<StatCard label="Total Routes"   value={scan.total_routes}   icon={MapPin}        variant="default" />
+<StatCard label="Routes Scanned" value={scan.routes_scanned} icon={CheckCircle2}  variant="secondary" />
+<StatCard label="Total Flights"  value={scan.total_flights}  icon={PlaneTakeoff}  variant="primary" />
+```
+
+#### 5.4 Progress card (running/pending only)
+
+Replace the existing progress bar section with:
+
+```
+┌────────────────────────────────────────────────────────────┐
+│  ↻ (Loader2, animated)   Scanning in progress...          │
+│  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━     38% │
+│  23 of 60 routes  ·  Auto-refreshing every 3 seconds      │
+└────────────────────────────────────────────────────────────┘
+```
+
+Card: `bg-surface rounded-lg p-5 mb-6 border border-running-border` (using CSS var `--color-status-running-border`) with a subtle `box-shadow: 0 0 0 3px var(--color-status-running-border)` pulse animation.
+
+Progress bar: 4px height, Primary fill, Surface 2 track, `transition-all duration-300`.
+
+#### 5.5 Routes table
+
+**Header row:** `bg-surface-2`, column headers in `label-sm uppercase text-on-surface-variant`. Sortable columns (Destination, Flights, Min Price) show `ChevronUp`/`ChevronDown` icon (14px) trailing the header label. Active sort column header text is `text-primary`.
+
+**Body rows:**
+- Height: `py-4` (comfortable)
+- Hover: `hover:bg-surface-2 transition-colors duration-150`
+- Cursor: `cursor-pointer`
+
+**Destination cell:**
+- Expand chevron: `ChevronRight` (16px, `text-on-surface-variant`), rotates to `ChevronDown` on expand via `transition-transform duration-200`
+- IATA code: `font-mono text-primary bg-primary-container px-2 py-0.5 rounded-sm text-sm font-medium` (inline chip)
+- Airport name: `text-sm text-on-surface-variant ml-2`
+
+**Min Price cell:** `text-secondary font-medium` — distinct from avg/max which are `text-on-surface-variant`
+
+**Expanded sub-row:**
+- Background: `bg-[#F8FDF9]` (very light green tint, hardcoded — not a token)
+- Transition: the row must not snap in/out. Use `max-height: 0 → max-height: 600px` with `overflow-hidden transition-all duration-250 ease-in-out` applied to a wrapper div
+- Sub-table headers: `label-sm uppercase text-on-surface-variant bg-[#EEF7F0]`
+- Sub-table `Date` column: indent 32px to visually nest under the destination
+- `Price` column: `text-secondary font-medium`, right-aligned
+- Loading state inside expanded row: `<SkeletonTableRow />` × 3
+
+#### 5.6 Empty states (no routes)
+
+```
+completed with 0 routes:
+  <EmptyState icon={MapPin} title="No routes found"
+    description="No direct flights for the selected airports and date range." />
+
+failed:
+  <EmptyState icon={AlertCircle} title="Scan failed"
+    description={scan.error_message || 'An error occurred during the scan.'} />
+
+running/pending with 0 routes:
+  (handled by progress card above — no separate empty state needed)
+```
+
+**Phase 5 acceptance criteria:**
+- [ ] Header card shows origin → destination, status chip, and all metadata
+- [ ] Progress card shows only when scan is running or pending
+- [ ] Active sort column header is visually distinguished
+- [ ] IATA codes render as inline chips in the destination cell
+- [ ] Expanding a route row is animated (not instant snap)
+- [ ] Sub-table flights have a distinct background from parent rows
+- [ ] Min price is green; avg/max are muted
+
+---
+
+### Phase 6 — Airports page
+
+**File:** `frontend/src/pages/Airports.tsx`
+
+**Objective:** Transform the blank page into a functional search experience with a real results table.
+
+#### 6.1 Page header
+
+```
+"Airports" (headline-md) + "Search the global airport database" (body-lg, text-on-surface-variant, mt-1)
+```
+
+#### 6.2 Search bar
+
+Single full-width input with a leading `Search` icon (20px, `text-on-surface-variant`, left-padded inside input via `pl-12`). Input height: 48px. Remove the separate `<button>Search</button>` — search triggers on keystroke debounce (already implemented in component) and on Enter.
+
+Replace the `bg-white rounded-lg shadow p-6 mb-6` wrapper card with just the input standing on the surface background, `mb-6`.
+
+#### 6.3 Results — desktop (≥ 768px)
+
+Standard data table inside a `bg-surface rounded-lg shadow-1 overflow-hidden` card.
+
+Columns: IATA (72px fixed, mono-md, Primary) | Airport Name | City | Country | Copy
+
+Copy cell: `<Button variant="icon">` with `Copy` icon. On click: `navigator.clipboard.writeText(airport.iata)` then show inline "Copied!" `label-sm text-secondary` tooltip for 2s (CSS opacity transition).
+
+#### 6.4 Results — mobile (< 768px)
+
+List view (not table). Each airport row:
+```
+┌──────────────────────────────────┐
+│  FRA   Frankfurt Airport   [⎘]  │
+│  Frankfurt, Germany              │
+└──────────────────────────────────┘
+```
+
+IATA code: `font-mono text-primary font-medium` (no chip on mobile to save space).
+
+#### 6.5 Empty and initial states
+
+Before any search (query length < 2):
+```
+<EmptyState
+  icon={Search}
+  title="Search airports"
+  description="Enter an IATA code, city name, or airport name to search."
+/>
+```
+
+After search with no results:
+```
+<EmptyState
+  icon={MapPin}
+  title={`No airports found for "${query}"`}
+  description="Try a different IATA code or city name."
+/>
+```
+
+**Phase 6 acceptance criteria:**
+- [ ] Search icon is visually inside the input field
+- [ ] No search button — search triggers on input change (debounced)
+- [ ] IATA code has monospace font and Primary colour
+- [ ] Copy button works and shows transient feedback
+- [ ] Initial empty state shows on page load
+- [ ] Table/list switches between layouts at 768px
+
+---
+
+### Phase 7 — Logs page
+
+**File:** `frontend/src/pages/Logs.tsx`
+
+**Objective:** Make the log viewer scannable by adding log-level colour coding, monospace message text, and a cleaner filter bar.
+
+#### 7.1 Page header
+
+```
+"System Logs" (headline-md) + auto-refresh toggle (icon button, `RefreshCw` icon, top-right)
+```
+
+The auto-refresh toggle starts as `false`. When active, it polls every 5s and shows a rotating icon.
+
+#### 7.2 Filter bar
+
+Replace the current two-column grid card with a single horizontal filter row at the top of the content area (no card wrapper):
+
+```
+[All Levels ▼]   [Search messages...  🔍]   [Clear filters ✕]  ← only visible when filters active
+```
+
+- Level select: 140px wide, outlined input style, `ChevronDown` trailing icon
+- Search: flex-1, outlined input with leading `Search` icon (same pattern as Airports §6.2)
+- Clear button: `text` variant Button with `X` icon, only rendered when `level || searchQuery`
+
+#### 7.3 Log row design
+
+Each log entry is a `px-4 py-3 border-b border-outline-variant` row (no card wrapper — the list is the card).
+
+```
+┌─────────────────────────────────────────────────────────────────────────┐
+│  ● INFO   Flight Radar API v2.0 startup complete           22:57:33    │
+│           api_server · lifespan · line 310                             │
+└─────────────────────────────────────────────────────────────────────────┘
+```
+
+- Level badge: fixed 64px wide, `label-md`, colours from the `getLevelColor` map (keep existing logic, update classes to use design tokens)
+- Message: `font-mono text-sm text-on-surface`, `break-all` on overflow
+- Metadata line: `body-sm text-on-surface-variant mt-0.5`, items separated by `·`
+- Timestamp: right-aligned, `body-sm font-mono text-on-surface-variant`, fixed width
+
+**Row background tints:**
+```
+ERROR    → bg-[#FFF5F5]   (very subtle, not the full error-container)
+WARNING  → bg-[#FFFBF0]
+DEBUG    → default
+INFO     → default
+CRITICAL → bg-[#FFF0F0]
+```
+
+#### 7.4 Loading state
+
+While `loading === true`: render 8× `<SkeletonTableRow />`.
+
+**Phase 7 acceptance criteria:**
+- [ ] Level badge has correct colour per level
+- [ ] Message text uses monospace font
+- [ ] ERROR and WARNING rows have a background tint
+- [ ] Filter row is horizontal (not a two-column card grid)
+- [ ] Clear filters button only appears when filters are active
+- [ ] Loading state uses skeleton rows
+
+---
+
+## 7. Files Changed Summary
+
+| File | Phase | Type |
+|------|-------|------|
+| `frontend/index.html` | 1 | Update — add Google Fonts |
+| `frontend/src/index.css` | 1 | Replace — add design tokens |
+| `frontend/src/components/Layout.tsx` | 1 | Replace — sidebar + bottom nav |
+| `frontend/src/components/Button.tsx` | 2 | New |
+| `frontend/src/components/StatusChip.tsx` | 2 | New |
+| `frontend/src/components/StatCard.tsx` | 2 | New |
+| `frontend/src/components/EmptyState.tsx` | 2 | New |
+| `frontend/src/components/SkeletonCard.tsx` | 2 | New |
+| `frontend/src/components/SegmentedButton.tsx` | 2 | New |
+| `frontend/src/components/AirportChip.tsx` | 2 | New |
+| `frontend/src/components/Toast.tsx` | 2 | Update — visual only |
+| `frontend/src/pages/Dashboard.tsx` | 3 | Replace |
+| `frontend/src/pages/Scans.tsx` | 4 | Replace |
+| `frontend/src/pages/ScanDetails.tsx` | 5 | Replace |
+| `frontend/src/pages/Airports.tsx` | 6 | Replace |
+| `frontend/src/pages/Logs.tsx` | 7 | Replace |
+| `frontend/src/components/AirportSearch.tsx` | 4, 6 | Update — visual styling only |
+
+**Files that must NOT change:**
+- `frontend/src/api.ts` — all API calls, types, and interfaces remain identical
+- `frontend/src/App.tsx` — routing stays the same
+- `frontend/src/main.tsx` — entry point unchanged
+- All backend Python files
+- `database/`, `tests/`, `docker-compose.yml`, `nginx.conf`
+
+---
+
+## 8. Dependency Notes
+
+### `lucide-react`
+Tree-shakeable. Import only the icons used per file:
+```tsx
+import { PlaneTakeoff, CheckCircle2 } from 'lucide-react';
+```
+Never import `import * from 'lucide-react'`.
+
+### `clsx` + `tailwind-merge`
+Use together for conditional class merging in components:
+```tsx
+import { clsx } from 'clsx';
+import { twMerge } from 'tailwind-merge';
+const cn = (...args: Parameters<typeof clsx>) => twMerge(clsx(...args));
+```
+Export this `cn` helper from a shared `frontend/src/lib/utils.ts` file.
+
+---
+
+## 9. Implementation Order
+
+Execute phases strictly in order 1 → 7. Do not start Phase 3 before Phase 2 is complete. After each phase:
+
+1. Run `npm run build` — must produce zero TypeScript errors
+2. Run `npm run lint` — must produce zero lint errors
+3. Verify the phase acceptance criteria manually in the browser
+4. Commit with a descriptive message (per `CLAUDE.md` workflow rules)
+5. Push to remote
+
+---
+
+## 10. Out of Scope for This PRD
+
+The following items are defined in `DESIGN_SYSTEM.md` but intentionally deferred:
+
+| Feature | Reason deferred |
+|---------|-----------------|
+| Dark mode | Tokens are structured to support it; implementation requires a separate pass |
+| Page transition animations | Low impact, adds complexity |
+| Floating label inputs (full MD3 pattern) | Requires more JS; simplified outlined labels are acceptable for v1 |
+| SVG illustrations in empty states | Placeholder icon circles are sufficient for v1 |
+| Sidebar collapse to 72px rail | Not needed until the app has more nav items |
+| `react-router` `useNavigate` usage in `Scans.tsx` §4.8 | Should still replace `window.location.href` — this is a bug fix included in scope |
+
+---
+
+*— PRD v1.0 · Design System Implementation · Ready for Implementation —*