body, html {
  overflow: hidden; }

.historical-event-overlay {
  position: fixed;
  z-index: 9999;
  background: rgba(0, 0, 0, 0.5);
  width: 100%;
  height: 100%;
  top: 0;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-pack: center;
  -ms-flex-pack: center;
  justify-content: center;
  -webkit-box-align: center;
  -ms-flex-align: center;
  align-items: center; }
  .historical-event-overlay .btn--action {
    margin-left: auto;
    margin-right: auto; }