File: assets/vendor/bootstrap-md/scss/addons/_hierarchical-display.scss

.zmd-hierarchical-display {
  visibility: hidden;
  &.in {
    visibility: visible;
  }
}
.zmd-hierarchical-displaying {
  visibility: visible;
}

.animation {
  animation-duration: 1s;
  animation-fill-mode: both;
}

.animation.zoomedIn,
.animation.zoomedOut {
  animation-timing-function: cubic-bezier(.55, 0, .1, 1); // "Swift Out" easing curve
}

@keyframes zoomedIn {
  from {
    transform: scale(0);
  }
  to {
    transform: scale(1);
  }
}

@keyframes zoomedOut {
  from {
    transform: scale(1);
  }
  to {
    transform: scale(0);
  }
}

.zoomedIn {
  animation-name: zoomedIn;
}

.zoomedOut {
  animation-name: zoomedOut;
}