Inserting a tooltip marker in the primary menu dropdown

Inserting a small triangular marker to the dropdown menu at the top left, pointing to the parent link in the main menu.

/* Insert a tooltip marker in the primary menu dropdown */
.sub-menu:before {
   content: "";
   background: #fff;
   width: 10px; height: 10px;
   margin-top:-5px;
   position: absolute;
   top:0px; left: 20px;
   transform: rotate(45deg);
}