#main {
    width: 100%;
    height: calc(100vh - 241px);
    background-image: url("/img/main/main_banner.jpg");
    background-repeat: repeat-x;
    background-size: auto 100%;
    background-position: 0 center;
    animation: moveBackground 15s linear infinite;
}

@keyframes moveBackground {
    0% {
        background-position-x: 0;
    }
    100% {
        background-position-x: -100vw;
    }
 }

 @media (max-width: 550px) {
    #main {
        animation: moveBackground 7s linear infinite;
    }
}