#overlay {
  display: none;
  position: fixed;
  top: 0; left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.6);
  z-index: 1000;
}

#modal {
  display: none;
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  background: #fff;
  padding: 20px;
  width: 800px;
  border-radius: 8px;
  z-index: 1001;
}