diff --git a/backend/static/js/app.js b/backend/static/js/app.js
index c863241..c5620fe 100644
--- a/backend/static/js/app.js
+++ b/backend/static/js/app.js
@@ -193,12 +193,28 @@ const App = (() => {
   }
 
   function _openSidebar() {
-    document.getElementById('sidebar')?.classList.add('open');
+    const sidebar = document.getElementById('sidebar');
+    if (!sidebar) return;
+    // Inline-Styles: unabhängig vom CSS-Cache-Stand
+    sidebar.style.cssText = [
+      'display:flex',
+      'position:fixed',
+      'top:0', 'left:0', 'bottom:0',
+      'width:240px',
+      'z-index:2000',
+      'background:var(--c-surface,#fff)',
+      'flex-direction:column',
+      'overflow:hidden',
+      'box-shadow:4px 0 24px rgba(0,0,0,0.22)',
+      'border-right:1px solid var(--c-border-light,#eee)',
+    ].join(';');
     document.getElementById('sidebar-backdrop')?.classList.add('visible');
   }
 
   function _closeSidebar() {
-    document.getElementById('sidebar')?.classList.remove('open');
+    const sidebar = document.getElementById('sidebar');
+    if (!sidebar) return;
+    sidebar.style.cssText = ''; // alle Inline-Styles weg → CSS übernimmt wieder
     document.getElementById('sidebar-backdrop')?.classList.remove('visible');
   }
 
diff --git a/backend/static/sw.js b/backend/static/sw.js
index becba5a..6f6b7c6 100644
--- a/backend/static/sw.js
+++ b/backend/static/sw.js
@@ -3,7 +3,7 @@
    Offline-Cache + Push Notifications
    ============================================================ */
 
-const CACHE_VERSION = 'by-v30';
+const CACHE_VERSION = 'by-v31';
 const CACHE_STATIC  = `${CACHE_VERSION}-static`;
 
 // Diese Dateien werden beim Install gecacht (App Shell)
@@ -40,6 +40,9 @@ self.addEventListener('activate', event => {
         keys.filter(k => k !== CACHE_STATIC).map(k => caches.delete(k))
       ))
       .then(() => self.clients.claim())
+      // Alle offenen Fenster neu laden, damit neues CSS/JS aktiv wird
+      .then(() => self.clients.matchAll({ type: 'window' }))
+      .then(clients => clients.forEach(c => c.navigate(c.url)))
   );
 });