Update main.less to fix #1510

Update main.less to fix #1510. There was an alignment issue on Safari because of missing vendor prefix ```-webkit``` on ```transform``` on the ```.points-on-top``` class.

public/css/main.less

@@ -577,6 +577,7 @@ thead {
   margin: 0 auto;
   position: relative;
   top: 50%;
+  -webkit-transform: translateY(-50%);
   transform: translateY(-50%);
 }