diff --git a/web/app.py b/web/app.py
index bcc983a..17d560c 100644
--- a/web/app.py
+++ b/web/app.py
@@ -133,7 +133,7 @@ async def security_headers(request: Request, call_next):
         "default-src 'self'; "
         "script-src 'self' https://cdn.tailwindcss.com https://unpkg.com; "
         "style-src 'self' https://cdn.tailwindcss.com https://unpkg.com 'unsafe-inline'; "
-        "img-src 'self' data: https://*.tile.openstreetmap.org https://tile.openstreetmap.org; "
+        "img-src 'self' data: https://*.tile.openstreetmap.org https://tile.openstreetmap.org https://unpkg.com; "
         "connect-src 'self'; frame-ancestors 'none';"
     )
     return resp
diff --git a/web/static/map.js b/web/static/map.js
index d9dc155..9cc6c3e 100644
--- a/web/static/map.js
+++ b/web/static/map.js
@@ -1,15 +1,13 @@
 // lazyflat — Leaflet flat map
-// A single Leaflet map instance; re-initialised after every HTMX swap of
-// the Wohnungen body. Also flushes size when the view toggle flips from
-// list to map (Leaflet needs invalidateSize on a hidden-then-shown map).
+// Initialised LAZILY: we only build the Leaflet instance when the container
+// actually has a rendered size (> 0 height). Building it on a hidden 0×0
+// container leaves Leaflet in a state where tiles never load.
 
 let mapInstance = null;
 const BERLIN_CENTER = [52.52, 13.405];
 const BERLIN_ZOOM = 11;
 
-function initFlatsMap() {
-  const el = document.getElementById("flats-map");
-  if (!el || typeof L === "undefined") return;
+function buildMap(el) {
   if (mapInstance) {
     try { mapInstance.remove(); } catch (e) {}
     mapInstance = null;
@@ -25,29 +23,23 @@ function initFlatsMap() {
   L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png", {
     attribution: "© OpenStreetMap",
     maxZoom: 18,
+    subdomains: "abc",
   }).addTo(mapInstance);
 
   let data = [];
-  try {
-    data = JSON.parse(el.dataset.flats || "[]");
-  } catch (e) {
-    console.warn("flats-map: bad JSON in data-flats", e);
-  }
-
+  try { data = JSON.parse(el.dataset.flats || "[]"); } catch (e) {}
   const bounds = [];
   data.forEach((f) => {
     if (typeof f.lat !== "number" || typeof f.lng !== "number") return;
-    const m = L.marker([f.lat, f.lng]).addTo(mapInstance);
     const rent = f.rent ? Math.round(f.rent) + " €" : "";
     const rooms = f.rooms ? f.rooms + " Zi" : "";
     const size = f.size ? Math.round(f.size) + " m²" : "";
     const meta = [rooms, size, rent].filter(Boolean).join(" · ");
     const safeAddr = (f.address || "").replace(/</g, "&lt;");
     const safeLink = (f.link || "#").replace(/"/g, "&quot;");
-    m.bindPopup(
-      `<b>${safeAddr}</b>` +
-        (meta ? `<br>${meta}` : "") +
-        `<br><a href="${safeLink}" target="_blank" rel="noopener">Zur Anzeige →</a>`,
+    L.marker([f.lat, f.lng]).addTo(mapInstance).bindPopup(
+      `<b>${safeAddr}</b>` + (meta ? `<br>${meta}` : "") +
+      `<br><a href="${safeLink}" target="_blank" rel="noopener">Zur Anzeige →</a>`,
     );
     bounds.push([f.lat, f.lng]);
   });
@@ -58,10 +50,20 @@ function initFlatsMap() {
   }
 }
 
-function flushMapSize() {
-  if (mapInstance) {
-    setTimeout(() => mapInstance.invalidateSize(), 50);
+function ensureMap() {
+  const el = document.getElementById("flats-map");
+  if (!el || typeof L === "undefined") return;
+
+  // Container not actually visible yet → bail, we'll retry when the view toggles.
+  if (el.clientHeight < 10) return;
+
+  // Existing instance bound to THIS element → just recheck size.
+  if (mapInstance && mapInstance._container === el) {
+    try { mapInstance.invalidateSize(); } catch (e) {}
+    return;
   }
+
+  buildMap(el);
 }
 
 function wireViewToggle() {
@@ -69,33 +71,35 @@ function wireViewToggle() {
     if (r.dataset.wired === "1") return;
     r.dataset.wired = "1";
     r.addEventListener("change", (e) => {
-      try {
-        localStorage.setItem("lazyflat_view_mode", e.target.value);
-      } catch (err) {}
-      flushMapSize();
+      try { localStorage.setItem("lazyflat_view_mode", e.target.value); } catch (err) {}
+      // Wait for CSS :has() to reflow, then build/size the map.
+      requestAnimationFrame(() => requestAnimationFrame(ensureMap));
+      // belt & suspenders — re-check a couple more times in case of layout shifts.
+      setTimeout(ensureMap, 120);
+      setTimeout(ensureMap, 400);
     });
   });
 }
 
 function restoreView() {
   let stored = null;
-  try {
-    stored = localStorage.getItem("lazyflat_view_mode");
-  } catch (err) {}
+  try { stored = localStorage.getItem("lazyflat_view_mode"); } catch (e) {}
   if (!stored) return;
-  const el = document.querySelector(
-    `input[name="view_mode"][value="${stored}"]`,
-  );
+  const el = document.querySelector(`input[name="view_mode"][value="${stored}"]`);
   if (el && !el.checked) {
     el.checked = true;
-    flushMapSize();
+    // Manually dispatching change would bubble and double-fire; call directly.
+    requestAnimationFrame(() => requestAnimationFrame(ensureMap));
+    setTimeout(ensureMap, 120);
+    setTimeout(ensureMap, 400);
   }
 }
 
 function onReady() {
-  initFlatsMap();
   wireViewToggle();
   restoreView();
+  ensureMap();  // handles the case where map view is already visible
 }
+
 document.addEventListener("DOMContentLoaded", onReady);
 document.body && document.body.addEventListener("htmx:afterSwap", onReady);