.subitem-mega {
  position: relative;
  padding-right: 12px; 
  display: inline-block; 
}

.subitem-mega::before {
  content: "";
  position: absolute;
  right: 0;     
  top: 50%;
  transform: translateY(-50%); 
  width: 2px;   
  height: 80%;  
background: red;
}