fix: navigation dropdowns now work with actual menu structure

- Added desktop media query (min-width: 993px) to hvac-menu-system.css
- Fixed critical issue where menu was hidden on desktop due to missing CSS rule
- Re-enabled CSS enqueue in class-hvac-menu-system.php after previous debugging
- Navigation now displays as horizontal navbar with working dropdown menus
- Verified working on staging: dropdowns open/close correctly on desktop
- Maintained mobile hamburger menu functionality

Root cause: Mobile CSS rules hid menu at ≤992px but no desktop rule showed it at ≥993px
Solution: Added display:flex !important for desktop breakpoint

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

CLAUDE.md

@@ -292,3 +292,4 @@ The following systems are commented out in `/includes/class-hvac-plugin.php` lin
 - **Custom Event Edit Implementation (2025-08-18)**: Implemented secure custom event editing without JavaScript dependencies. Created HVAC_Custom_Event_Edit class with proper authorization checks using role verification instead of capability checks. Fixed permission bug where `current_user_can('hvac_trainer')` was incorrectly used - custom roles are not capabilities. Solution: use `in_array('hvac_trainer', $user->roles)` for proper role checking. Added professional CSS styling matching registration page design with 1200px container width, card-based layout, and proper z-index layering to prevent navigation overlap. Successfully deployed to production with full functionality verified.
 - **JavaScript Simplification (2025-08-18)**: Removed 200+ lines of unnecessary jQuery compatibility code following WordPress best practices. Eliminated hvac-jquery-compatibility-fix.js and class-hvac-jquery-compatibility.php. Updated community-login.js to use standard `jQuery(document).ready()` pattern. WordPress handles jQuery in no-conflict mode automatically - complex compatibility layers violate best practices and add unnecessary complexity. Production deployment successful with all functionality working correctly.
 - **Event Management Page UI Enhancement (2025-08-19)**: Improved trainer/event/manage/ page UX by removing redundant buttons and adding helpful event creation guide. Changes: Removed "Add New Event" and "View My Events" buttons to reduce clutter, added breadcrumb navigation to harmonize with other trainer pages, introduced "Quick Guide to Creating Events" section with 8 essential bullet points covering event types, requirements, registration options, and approval process. Guide styled with light gray background for improved readability. Maintains The Events Calendar shortcode integration.
+- **Navigation Menu Desktop Visibility Fix (2025-08-21)**: Resolved critical navigation issue where HVAC trainer menu was completely invisible on desktop browsers. Root cause: CSS responsive design was incomplete - mobile rule set `display: none !important` for menu at ≤992px, but no corresponding desktop rule existed to show menu at ≥993px. HTML structure and JavaScript handlers were functioning correctly, but CSS was hiding the entire navigation. Solution: Added desktop media query to `assets/css/hvac-menu-system.css` with `@media (min-width: 993px) { .hvac-trainer-menu { display: flex !important; visibility: visible !important; opacity: 1 !important; } }`. Investigation used Zen debug workflow with GPT-5, systematic DOM inspection, computed style analysis, and browser width testing. Navigation now displays correctly as horizontal navbar with working dropdown functionality. Deployed to staging and user-verified working on desktop browsers.

assets/css/hvac-menu-system.css

@@ -182,6 +182,20 @@
     transform: rotate(-45deg) translate(7px, -6px);
 }
 
+/* Desktop Responsive Styles */
+@media (min-width: 993px) {
+    .hvac-hamburger-menu {
+        display: none !important;
+    }
+    
+    .hvac-page-wrapper .hvac-trainer-menu,
+    .hvac-trainer-menu {
+        display: flex !important;
+        visibility: visible !important;
+        opacity: 1 !important;
+    }
+}
+
 /* Mobile Responsive Styles */
 @media (max-width: 992px) {
     .hvac-trainer-nav {