html, body {
  background: #000;
  margin: 0;
  width: 100%;
  height: 100%;

  cursor: pointer;
}

#container {
  overflow: auto;
  display: table-cell;
  vertical-align: middle;
}
#container img {
  width: auto;
  height: auto;

  margin: auto;

  max-width: 100%;
  max-height: 100%;

  display: none;
}
#container img:first-child {
  display: block;
}