Chekistchek

#start_display {
    width: 100px;
    height: 100px;
    position: fixed;
    z-index: -999;
    animation-duration: 1s;
    animation-name: disappear; 
}
@keyframes disappear {
    0% {background-color: white;z-index: 999;}
    80% {background-color: white;}
    99.9% {z-index: 999}
    100% {background-color: none;z-index: -999;}
}