blocks/myoverview/styles.css

   1 /* Hide the first dropdown-divider if no filter option element is listed before it.
   2    This can happen for some subset configurations of the block_myoverview course filter. */
   3 .block_myoverview button#groupingdropdown + .dropdown-menu li:first-of-type.dropdown-divider:first-of-type {
   4     display: none;
   5 }