Align Bootstrap 3 Modal to Center Vertically

.modal {text-align: center;}
.modal-dialog {display: inline-block; text-align: left; vertical-align: middle;}
@media screen and (min-width: 768px) {
.modal:before {display: inline-block; vertical-align: middle; content: ” “; height: 100%;}
}

.modal {text-align: center;}
.modal-dialog {display: inline-block; text-align: left; vertical-align: middle;}
@media screen and (min-width: 768px) {
.modal:before {display: inline-block; vertical-align: middle; content: ” “; height: 100%;}
}