.img-overlay {
  position: fixed;
  top: 90px;
  max-height: 80%;
  left: 50%;
  transform: translate(-50%, 0) scale(0, 0);
  z-index: 10;
  box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);
  transition: all .3s ease;
}

.overlay-dark {
  top: 0;
  position: fixed;
  background-color: #000;
  opacity: .9;
  width: 100%;
  height: 100%;
  z-index: 5;
  display: none;
}