.badge {
  display: inline-flex;
  padding-left: 5px;
  overflow: hidden;
  background-color: #000;
  border-radius: 5px;
  line-height: 1.6;
  color: #fff !important;
  text-decoration: none !important;
}

.doi {
  background-color: #09c;
  margin-left: 5px;
  padding: 0 5px;
}

.badge:hover > .doi {
  background-color: #006a8d;
}
