Implement modern sidebar navigation with hamburger menu

- Add responsive sidebar with hamburger toggle functionality
- Implement dual toggle buttons (inner/outer) for better UX
- Fix sidebar positioning to not overlap header and footer
- Add sticky footer with proper z-index layering
- Download and integrate Bootstrap source maps locally
- Optimize toggle icons: smaller, cleaner, no button styling
- Ensure sidebar respects footer boundaries
- Add smooth transitions and hover effects
- Fix active page highlighting and folder auto-expansion
- Create professional W3Schools-style navigation
- Maintain full offline capability with local assets

engine/core/index.php

@@ -427,10 +427,16 @@ private function autoLinkPageTitles($content) {
                 
                 if ($hasChildren) {
                     $folderId = 'folder-' . str_replace('/', '-', $item['path']);
-                    $html .= '<span class="nav-link folder-toggle" data-bs-toggle="collapse" data-bs-target="#' . $folderId . '" aria-expanded="false">';
+                    
+                    // Check if this folder contains the active page
+                    $containsActive = $this->folderContainsActivePage($item['children']);
+                    $ariaExpanded = $containsActive ? 'true' : 'false';
+                    $collapseClass = $containsActive ? 'collapse show' : 'collapse';
+                    
+                    $html .= '<span class="nav-link folder-toggle" data-bs-toggle="collapse" data-bs-target="#' . $folderId . '" aria-expanded="' . $ariaExpanded . '">';
                     $html .= '<i class="arrow bi bi-chevron-right"></i> ' . htmlspecialchars($item['title']);
                     $html .= '</span>';
-                    $html .= '<ul class="nav flex-column ms-2 collapse" id="' . $folderId . '">';
+                    $html .= '<ul class="nav flex-column ms-2 ' . $collapseClass . '" id="' . $folderId . '">';
                     $html .= $this->renderMenu($item['children'], $level + 1);
                     $html .= '</ul>';
                 } else {
@@ -449,6 +455,21 @@ private function autoLinkPageTitles($content) {
         }
         return $html;
     }
+    
+    private function folderContainsActivePage($children) {
+        foreach ($children as $child) {
+            if ($child['type'] === 'folder') {
+                if (!empty($child['children']) && $this->folderContainsActivePage($child['children'])) {
+                    return true;
+                }
+            } else {
+                if (isset($_GET['page']) && $_GET['page'] === $child['path']) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
 }
 
 $cms = new CodePressCMS($config);