diff --git a/agaric/sass/agaric/_base.elements.scss b/agaric/sass/agaric/_base.elements.scss
index b611e15..4a3f315 100644
--- a/agaric/sass/agaric/_base.elements.scss
+++ b/agaric/sass/agaric/_base.elements.scss
@@ -131,3 +131,9 @@ hr {
     color: $dandelion-light;
   }
 }
+
+// Ensure embedded media is responsive
+
+iframe {
+  width: 100%;
+}