body, html {
    height: 100%;
 background-color: black;
}

#mainImage{
    position: fixed;
    display: none;
    margin-left: auto;
    margin-right: auto;
    max-width:100%;
    max-height:100%; 
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    image-orientation: from-image;
}
#config{
 display:block;
  background-color: white;
}