#overlay {
  width: 100%;
  height: 100%;
  background: #000;
  position: fixed;
  left: 0;
  top: 0;
  z-index: 9999;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s cubic-bezier(0.165, 0.84, 0.44, 1); }
  #overlay.show {
    opacity: 1;
    pointer-events: all; }