ul {
  list-style-type: none;
  display: flex;
  flex-direction: row;
}

li {
  padding: 10px;
}

.custom-border {
  position: relative;
}

.custom-border:after {
  content: " ";
  position: absolute;
  border-left: 1px #6c757d solid;
  top: 35%;
  right: 0;
  height: 30%;
  margin-top: auto;
  margin-bottom: auto;
}