html,
body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #000000;
    /*background-image: url("/loading1.gif");*/
    background-repeat: no-repeat;
    background-position: center;
    background-size: 10%;
    animation: fadeOut 5s forwards;
}

@keyframes fadeOut {
    0% {
        background-size: 10%;
    }
    100% {
        background-size: 100%;
    }
}