@import url('https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css');
@import url('https://maxcdn.bootstrapcdn.com/font-awesome/4.6.1/css/font-awesome.min.css');

.panel-title > a {
  display: block;
  position: relative;
}
.panel-title > a:after {
  content: "\f078"; /* fa-chevron-down */
  font-family: 'FontAwesome';
  position: absolute;
  right: 0;
}
.panel-title > a[aria-expanded="true"]:after {
  content: "\f077"; /* fa-chevron-up */
}