.top-menu.d-md-block a {
  padding: 0 15px;
  text-decoration: none;
  color: #333;
  position: relative;
}

.top-menu.d-md-block a:not(:last-child)::after {
  content: "";
  position: absolute;
  right: 0;
  top: 25%;
  height: 50%;
  width: 1px;
  background-color: #ccc; 
}