#modal {
  display: none;
  opacity: 0;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.438);
  z-index: 9999;
}

#modal.modal-open {
  display: block;
  opacity: 1;
}