diff --git a/src/main.py b/src/main.py
index 351a55c..ead984c 100644
--- a/src/main.py
+++ b/src/main.py
@@ -235,7 +235,7 @@ class SecurityHeadersMiddleware(BaseHTTPMiddleware):
             "script-src 'self' 'unsafe-inline' https://cdn.jsdelivr.net; "
             "style-src 'self' 'unsafe-inline' https://fonts.googleapis.com https://cdn.jsdelivr.net; "
             "font-src 'self' https://fonts.gstatic.com; "
-            "img-src 'self' data: https://*.basemaps.cartocdn.com https://*.tile.openstreetmap.org; "
+            "img-src 'self' data: https://tile.openstreetmap.de; "
             "connect-src 'self' wss: ws:; "
             "frame-ancestors 'none'"
         )
diff --git a/src/static/js/components.js b/src/static/js/components.js
index 494d197..fb982b9 100644
--- a/src/static/js/components.js
+++ b/src/static/js/components.js
@@ -744,15 +744,11 @@ const UI = {
             if (layer instanceof L.TileLayer) this._map.removeLayer(layer);
         });
 
-        const theme = document.documentElement.getAttribute('data-theme') || 'dark';
-        const tileUrl = theme === 'dark'
-            ? 'https://{s}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png'
-            : 'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png';
-        const attribution = theme === 'dark'
-            ? '&copy; <a href="https://www.openstreetmap.org/copyright">OSM</a> &copy; <a href="https://carto.com/">CARTO</a>'
-            : '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a>';
+        // Deutsche OSM-Kacheln: deutsche Ortsnamen, einheitlich fuer beide Themes
+        const tileUrl = 'https://tile.openstreetmap.de/{z}/{x}/{y}.png';
+        const attribution = '&copy; <a href="https://www.openstreetmap.org/copyright">OpenStreetMap</a>';
 
-        L.tileLayer(tileUrl, { attribution, maxZoom: 18, subdomains: 'abcd' }).addTo(this._map);
+        L.tileLayer(tileUrl, { attribution, maxZoom: 18 }).addTo(this._map);
     },
 
     updateMapTheme() {