diff --git a/umap/static/umap/map.css b/umap/static/umap/map.css
index c8a43ce1..a9c0a746 100644
--- a/umap/static/umap/map.css
+++ b/umap/static/umap/map.css
@@ -1289,6 +1289,7 @@ a.add-datalayer:hover,
 }
 .umap-popup-content iframe {
     min-width: 310px;
+    max-width: 100%;
 }
 .umap-popup-content th,
 .umap-popup-content td {