Elastic: Fix border radius in popovers on small screens (#6911)

skins/elastic/styles/widgets/dialogs.less

@@ -55,6 +55,7 @@
         display: none;
     }
 
+    @media screen and (min-width: (@screen-width-small + 1px)) {
         .listing {
             li:first-child {
                 border-radius: .25rem .25rem 0 0;
@@ -65,6 +66,7 @@
             }
         }
     }
+}
 
 #rcmKSearchpane {
     width: auto;