div#phaser-container {
    width: 100%;
    max-height: 100vh;
    position: relative;
    margin: auto;
}
@media screen and (min-width: 474px) {
  div#phaser-container {
    max-width: 474px;
  }
}
#bg {
  position: fixed; 
  top: -50%; 
  left: -50%; 
  width: 200%; 
  height: 200%;
}
#bg img {
  position: absolute; 
  top: 0; 
  left: 0; 
  right: 0; 
  bottom: 0; 
  margin: auto; 
  min-width: 50%;
  min-height: 50%;
}