#overlay {
  opacity: 1;
  pointer-events: all;
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  background: #72808b;
  transition: opacity 1.5s ease;
  z-index: 1000;
}
body.fade-in #overlay {
  opacity: 0;
}