diff --git a/frontend/src/components/layout/AISidebar.tsx b/frontend/src/components/layout/AISidebar.tsx
index 8af1704..2942ac5 100644
--- a/frontend/src/components/layout/AISidebar.tsx
+++ b/frontend/src/components/layout/AISidebar.tsx
@@ -141,6 +141,7 @@ export function AISidebar() {
         initialWidth={320}
         minWidth={240}
         maxWidth={600}
+        handleSide="left"
         className="hidden md:flex border-l border-secondary-200 bg-white"
         data-testid="ai-sidebar-pane"
       >
diff --git a/frontend/src/components/layout/Sidebar.tsx b/frontend/src/components/layout/Sidebar.tsx
index 2bf8eae..4cd91d6 100644
--- a/frontend/src/components/layout/Sidebar.tsx
+++ b/frontend/src/components/layout/Sidebar.tsx
@@ -22,7 +22,6 @@ const navItems: NavItem[] = [
   { to: '/calendar', labelKey: 'nav.calendar', icon: navIcon('M8 7V3m8 4V3m-9 8h10M5 21h14a2 2 0 002-2V7a2 2 0 00-2-2H5a2 2 0 00-2 2v12a2 2 0 002 2z') },
   { to: '/dms', labelKey: 'nav.files', icon: navIcon('M7 21h10a2 2 0 002-2V9.414a1 1 0 00-.293-.707l-5.414-5.414A1 1 0 0012.586 3H7a2 2 0 00-2 2v14a2 2 0 002 2z') },
   { to: '/mail', labelKey: 'nav.email', icon: navIcon('M3 8l7.89 5.26a2 2 0 002.22 0L21 8M5 19h14a2 2 0 002-2V7a2 2 0 00-2-2H5a2 2 0 00-2 2v10a2 2 0 002 2z') },
-  { to: '/ai-assistant', labelKey: 'nav.aiAssistant', icon: navIcon('M9.75 17L9 20l-1 1h8l-1-1-.75-3M3 13h18M5 17h14a2 2 0 002-2V5a2 2 0 00-2-2H5a2 2 0 00-2 2v10a2 2 0 002 2z') },
   { to: '/settings', labelKey: 'nav.settings', icon: navIcon('M10.325 4.317c.426-1.756 2.924-1.756 3.35 0a1.724 1.724 0 002.573 1.066c1.543-.94 3.31.826 2.37 2.37a1.724 1.724 0 001.065 2.572c1.756.426 1.756 2.924 0 3.35a1.724 1.724 0 00-1.066 2.573c.94 1.543-.826 3.31-2.37 2.37a1.724 1.724 0 00-2.572 1.065c-.426 1.756-2.924 1.756-3.35 0a1.724 1.724 0 00-2.573-1.066c-1.543.94-3.31-.826-2.37-2.37a1.724 1.724 0 00-1.065-2.572c-1.756-.426-1.756-2.924 0-3.35a1.724 1.724 0 001.066-2.573c-.94-1.543.826-3.31 2.37-2.37.996.608 2.296.07 2.572-1.065z') },
   { to: '/audit-log', labelKey: 'nav.auditLog', icon: navIcon('M9 12h6m-6 4h6m2 5H7a2 2 0 01-2-2V5a2 2 0 012-2h5.586a1 1 0 01.707.293l5.414 5.414a1 1 0 01.293.707V19a2 2 0 01-2 2z') },
 ];
diff --git a/frontend/src/components/layout/TopBar.tsx b/frontend/src/components/layout/TopBar.tsx
index 4cdc6df..21317d8 100644
--- a/frontend/src/components/layout/TopBar.tsx
+++ b/frontend/src/components/layout/TopBar.tsx
@@ -108,15 +108,24 @@ export function TopBar() {
                 <h3 className="text-sm font-semibold text-secondary-900">{t('topbar.notifications')}</h3>
               </div>
               <ul className="max-h-64 overflow-y-auto py-1" role="list">
-                <li className="px-4 py-2 hover:bg-secondary-50 cursor-pointer text-sm text-secondary-700">
-                  Neuer Kontakt hinzugefügt: Max Mustermann
-                </li>
-                <li className="px-4 py-2 hover:bg-secondary-50 cursor-pointer text-sm text-secondary-700">
-                  Firma aktualisiert: TechCorp GmbH
-                </li>
-                <li className="px-4 py-2 hover:bg-secondary-50 cursor-pointer text-sm text-secondary-700">
-                  Meeting um 14:00 Uhr mit Müller AG
-                </li>
+                {[
+                  'Neuer Kontakt hinzugefügt: Max Mustermann',
+                  'Firma aktualisiert: TechCorp GmbH',
+                  'Meeting um 14:00 Uhr mit Müller AG',
+                ].map((msg, i) => (
+                  <li key={i} className="flex items-center justify-between px-4 py-2 hover:bg-secondary-50 cursor-pointer text-sm text-secondary-700 group">
+                    <span className="flex-1 truncate">{msg}</span>
+                    <button
+                      className="ml-2 p-1 rounded text-secondary-300 hover:text-danger-600 hover:bg-danger-50 opacity-0 group-hover:opacity-100 transition-opacity flex-shrink-0"
+                      aria-label="Benachrichtigung löschen"
+                      onClick={(e) => { e.stopPropagation(); }}
+                    >
+                      <svg className="w-3.5 h-3.5" fill="none" viewBox="0 0 24 24" stroke="currentColor" aria-hidden="true">
+                        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M6 18L18 6M6 6l12 12" />
+                      </svg>
+                    </button>
+                  </li>
+                ))}
               </ul>
             </div>
           )}
diff --git a/frontend/src/components/shared/SearchDropdown.tsx b/frontend/src/components/shared/SearchDropdown.tsx
index cdb5142..31b08b2 100644
--- a/frontend/src/components/shared/SearchDropdown.tsx
+++ b/frontend/src/components/shared/SearchDropdown.tsx
@@ -89,7 +89,7 @@ export function SearchDropdown({ placeholder }: SearchDropdownProps) {
         onFocus={() => query && setOpen(true)}
         onKeyDown={handleKeyDown}
         placeholder={placeholder || t('topbar.search')}
-        className="w-64 pl-10 pr-3 py-2 text-sm rounded-md border border-secondary-300 focus:outline-none focus:ring-2 focus:ring-primary-500 min-h-touch"
+        className="w-52 pl-10 pr-3 py-1.5 text-sm rounded-md border border-secondary-300 focus:outline-none focus:ring-2 focus:ring-primary-500 min-h-touch"
         aria-label={t('topbar.search')}
         role="combobox"
         aria-expanded={open}
diff --git a/frontend/src/components/ui/ResizablePanel.tsx b/frontend/src/components/ui/ResizablePanel.tsx
index 96bc1f6..5aff6cd 100644
--- a/frontend/src/components/ui/ResizablePanel.tsx
+++ b/frontend/src/components/ui/ResizablePanel.tsx
@@ -28,6 +28,8 @@ export interface ResizablePanelProps {
   className?: string;
   /** When false, panel becomes flex-1 with no drag handle */
   resizable?: boolean;
+  /** Which side the drag handle is on ('right' default, 'left' for right-aligned panels) */
+  handleSide?: 'left' | 'right';
   /** testid forwarded to the container div */
   'data-testid'?: string;
 }
@@ -39,6 +41,7 @@ export function ResizablePanel({
   children,
   className,
   resizable = true,
+  handleSide = 'right',
   ...rest
 }: ResizablePanelProps) {
   const [width, setWidth] = useState(initialWidth);
@@ -69,7 +72,8 @@ export function ResizablePanel({
     const handleMouseMove = (e: MouseEvent) => {
       if (!isResizing.current) return;
       const delta = e.clientX - startX.current;
-      const newWidth = Math.max(minWidth, Math.min(maxWidth, startWidth.current + delta));
+      const adjustedDelta = handleSide === 'left' ? -delta : delta;
+      const newWidth = Math.max(minWidth, Math.min(maxWidth, startWidth.current + adjustedDelta));
       // Apply width directly to DOM — no React re-render during drag
       if (panelRef.current) {
         panelRef.current.style.width = `${newWidth}px`;
@@ -101,7 +105,7 @@ export function ResizablePanel({
       document.removeEventListener('mousemove', handleMouseMove);
       document.removeEventListener('mouseup', handleMouseUp);
     };
-  }, [minWidth, maxWidth]);
+  }, [minWidth, maxWidth, handleSide]);
 
   return (
     <div
@@ -125,8 +129,11 @@ export function ResizablePanel({
       </div>
       {resizable && (
         <div
-          className="absolute top-0 right-0 h-full w-1.5 cursor-col-resize bg-transparent hover:bg-primary-300 active:bg-primary-400 transition-colors z-50 pointer-events-auto"
-          style={{ marginRight: '-3px' }}
+          className={clsx(
+            'absolute top-0 h-full w-1.5 cursor-col-resize bg-transparent hover:bg-primary-300 active:bg-primary-400 transition-colors z-50 pointer-events-auto',
+            handleSide === 'left' ? 'left-0' : 'right-0',
+          )}
+          style={handleSide === 'left' ? { marginLeft: '-3px' } : { marginRight: '-3px' }}
           onMouseDown={handleMouseDown}
           data-testid="resize-handle"
           role="separator"