diff --git a/agaric/css/agaric.css b/agaric/css/agaric.css
index 5287ed8..1bd957d 100644
--- a/agaric/css/agaric.css
+++ b/agaric/css/agaric.css
@@ -9983,6 +9983,9 @@ hr, .titlebar-bigborder, .media.media-comment, .media.media-comment + .media.med
 .navbar-brand a.navbar-item:focus, .navbar-brand a.navbar-item:hover {
   color: #CBC219; }
 
+iframe {
+  width: 100%; }
+
 .content .image {
   margin: 0;
   padding: 0; }