# Repair Orders Page Fix: Missing Mobile Navigation

## Bug
Hamburger menu button (top-right, next to account settings) did nothing when tapped on mobile. Page didn't have mobile navigation at all.

## Diagnosis
Compared `repair-orders.html` against working pages (`customers.html`, `appointments.html`). Found **three missing pieces**:

1. **Missing script include** — `shared/header-functionality.js` was not loaded. This file contains the `setupHeaderEventListeners()` function that registers the click handler for `#mobile-menu-btn`.

2. **Missing HTML** — The `#mobile-navigation` div (the nav panel that slides in on hamburger click) didn't exist in the page. Working pages had it after the desktop `#main-navigation` block.

3. **Missing CSS** — `#mobile-navigation` z-index and slide-in animation styles were not present in the inline `<style>` block.

## Fix Applied

### 1. Added script tag (alongside existing scripts at page bottom)
```html
<script type="module" src="shared/header-functionality.js"></script>
```

### 2. Added mobile-navigation HTML after `#main-navigation` close
```html
<div id="mobile-navigation" class="lg:hidden hidden py-3 md:py-4 border-t border-white/20">
  <div class="space-y-2">
    <!-- Dashboard link -->
    <!-- Repair Orders link (highlighted active) -->
    <!-- Appointments link -->
    <!-- Customers link -->
  </div>
</div>
```
Nav links use `mobile-nav-link` class and include inline SVG icons for each page. Active page gets `bg-white/20 text-white shadow-sm` highlight.

### 3. Added CSS (within `<style>` block)
```css
/* Mobile Navigation */
#mobile-navigation {
    z-index: 10000 !important;
}

#mobile-navigation {
    animation: mobileNavSlideIn 0.3s ease-out;
}

@keyframes mobileNavSlideIn {
    from { opacity: 0; transform: translateY(-20px); }
    to { opacity: 1; transform: translateY(0); }
}

@media (prefers-reduced-motion: reduce) {
    #mobile-navigation {
        transition: none;
        animation: none;
    }
}
```

## Pattern
This follows a recurring pattern in multi-page static web apps: when a UI feature works on some pages but not others, it's almost always one of:
1. **Script** not loaded on the broken page
2. **HTML element** not present on the broken page
3. **CSS rule** missing on the broken page

Check all three layers systematically.
