.card-header a:before {
  display: inline-block;
  font: normal normal normal 14px/1 FontAwesome;
  font-size: inherit;
  text-rendering: auto;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.card-header a[aria-expanded=false]:before {
  content: "\f107";
}

.card-header a[aria-expanded=true]:before {
  content: "\f106";
}

a:hover {
  color: #0056b3;
  text-decoration: none;
}