.glyphicon-plus:before {
  content: "\2b";
}


.collapse {
  display: none;
  visibility: hidden;
}
.collapse.in {
  display: block;
  visibility: visible;
}

.collapsing {
  position: relative;
  height: 0;
  overflow: hidden;
  -webkit-transition-timing-function: ease;
       -o-transition-timing-function: ease;
          transition-timing-function: ease;
  -webkit-transition-duration: .35s;
       -o-transition-duration: .35s;
          transition-duration: .35s;
  -webkit-transition-property: height, visibility;
       -o-transition-property: height, visibility;
          transition-property: height, visibility;
}