fix: force bookmarks pane expanded on mobile and ensure highlights pane sits above content on desktop

src/components/ThreePaneLayout.tsx

@@ -243,7 +243,7 @@ const ThreePaneLayout: React.FC<ThreePaneLayoutProps> = (props) => {
           <BookmarkList 
             bookmarks={props.bookmarks}
             onSelectUrl={props.onSelectUrl}
-            isCollapsed={props.isCollapsed}
+            isCollapsed={isMobile ? false : props.isCollapsed}
             onToggleCollapse={props.onToggleSidebar}
             onLogout={props.onLogout}
             viewMode={props.viewMode}

src/index.css

@@ -604,6 +604,11 @@ body.mobile-sidebar-open {
   height: 100%;
 }
 
+/* Ensure panes are stacked in the correct order on desktop */
+.three-pane .pane.sidebar { z-index: 1; }
+.three-pane .pane.main { z-index: 1; }
+.three-pane .pane.highlights { z-index: 2; }
+
 /* Mobile pane styles */
 @media (max-width: 768px) {
   /* Both sidepanes slide in as overlays */