.anim-body {
    width: 100%;
    height: 100vh;
    position: relative;
    background-color: black;
    background-size: cover;
}

.fog-anim {
    position: absolute;
    width: 100%;
    height: 100%;
    z-index: 1;
    left: 0px;
    top: 0px;
    background: url('../image/fog.png') repeat-x;
    background-size: 200% auto;
    background-position: 0 bottom;
    animation: fogAnim 60s;
    animation-timing-function: linear;
    animation-iteration-count: infinite;
}

@keyframes fogAnim {
    0% {
        background-position: -200% bottom;
    }
    100% {
        background-position: 0% bottom;
    }
}