diff --git a/web/login.js b/web/login.js
index 2978fec..a858e28 100644
--- a/web/login.js
+++ b/web/login.js
@@ -1,4 +1,5 @@
 const API_URL = 'https://fb.srv.medeba-media.de/api';
+const LOGIN_BROADCAST_KEY = 'fb-login-broadcast';
 
 function getRedirectTarget() {
   try {
@@ -69,6 +70,7 @@ async function handleLogin(event) {
     }
 
     updateStatus('Erfolgreich angemeldet. Weiterleitung…', false);
+    broadcastLogin();
     window.location.href = getRedirectTarget();
   } catch (error) {
     console.error('Login fehlgeschlagen:', error);
@@ -82,8 +84,42 @@ document.addEventListener('DOMContentLoaded', async () => {
     return;
   }
 
+  setupCrossTabLoginSync();
+
   const form = document.getElementById('loginForm');
   if (form) {
     form.addEventListener('submit', handleLogin);
   }
 });
+
+function broadcastLogin() {
+  try {
+    localStorage.setItem(LOGIN_BROADCAST_KEY, String(Date.now()));
+  } catch (error) {
+    // ignore storage errors (private mode, blocked)
+  }
+  if ('BroadcastChannel' in window) {
+    try {
+      const channel = new BroadcastChannel('fb-login');
+      channel.postMessage({ type: 'login', at: Date.now() });
+      channel.close();
+    } catch (error) {
+      // ignore
+    }
+  }
+}
+
+function setupCrossTabLoginSync() {
+  window.addEventListener('storage', (event) => {
+    if (event.key !== LOGIN_BROADCAST_KEY) return;
+    checkExistingSession();
+  });
+
+  if ('BroadcastChannel' in window) {
+    const channel = new BroadcastChannel('fb-login');
+    channel.addEventListener('message', (event) => {
+      if (!event || !event.data || event.data.type !== 'login') return;
+      checkExistingSession();
+    });
+  }
+}