Update back.html

back.html

@@ -10,7 +10,7 @@
   padding-top: 100%; /* 16:9 Aspect Ratio (divide 9 by 16 = 0.5625) */
 }
   .responsive-iframe {
-  position: flex;
+  position: relative;
   top: 0;
   left: 0;
   bottom: 0;