body:after {
    content: "";
    position: fixed;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    pointer-events: none;
    z-index: 1000;
    background-image: url('img/scan.png');
    background-repeat: all;
    background-position: 0px 0px;
    animation-name: Static;
    animation-duration: 0.8s;
    background-size: 100px;
    animation-iteration-count: infinite;
    animation-timing-function: steps(4);
}
@keyframes Static {
    0% { background-position: 0px 0px; }
    100% { background-position: 0px 4px; }
}