.np-dropfade,
.np-dropfade-enter {
  opacity: 0;
  overflow: hidden;
  height: 0;
}

.np-dropfade-enter-active {
  transition: height 150ms ease-in, opacity 150ms ease-in 150ms;
  opacity: 1;
}

.np-dropfade-enter-done,
.np-dropfade-exit {
  opacity: 1;
  height: auto;
}

.np-dropfade-exit-active {
  transition: opacity 150ms ease-in, height 150ms ease-in 150ms;
  opacity: 0;
}