Equalize separator heights in the sidebar buttons

Fix padding on the reset button so that all separators on the sidebar
end up with the same height, and add padding to the top of the sidebar
container to distance the separators from the top edge.

drag_and_drop_v2/public/css/drag_and_drop.css

@@ -502,6 +502,7 @@
         float: right;
         margin: 0;
         padding-right: -5px;
+        padding-top: 5px;
     }
 }
 
@@ -536,10 +537,6 @@
     display: block;
 }
 
-.xblock--drag-and-drop .reset-button {
-    margin-top: 3px;
-}
-
 /*** ACTIONS TOOLBAR END ***/
 
 /*** KEYBOARD HELP ***/