html { 
  background: url('bg.png') no-repeat left center fixed; 
  -webkit-background-size: contain;
  -moz-background-size: contain;
  -o-background-size: contain;
  background-size: contain;
}

.image-hint {
  position: absolute;
  bottom: 0;
  left: 0;
  width: 100%;
  text-align: left;
  font-size: 12px;
  color: #6d6d6d;
  padding: 5px;
}