MC-17948: Newsletter template preview show small section with scroll when image added

Author: Oleksandr Dubovyk

app/design/adminhtml/Magento/backend/web/css/styles-old.less

@@ -4060,6 +4060,16 @@
     }
 }
 
+.newsletter-template-preview {
+    height: 100%;
+    .cms-revision-preview {
+        height: 100%;
+        .preview_iframe {
+            height: calc(~'100% - 50px');
+        }
+    }
+}
+
 .admin__scope-old {
     .buttons-set {
         margin: 0 0 15px;