Do not set width and height to 100% for <img/> of document

Closes #14979

sao/src/sao.less

@@ -1387,12 +1387,14 @@ img.icon {
         object, iframe, img {
             max-width: 100%;
             min-height: 50vh;
-            height: 100%;
-            width: 100%;
             @media screen and (max-width: @screen-xs-max) {
                 min-height: 50vh;
             }
         }
+        object, iframe {
+            height: 100%;
+            width: 100%;
+        }
     }
     label {
         font-weight: normal;