.masterclassmodules {
    width: 100%;
    overflow: hidden;
}
.masterclassmodules-in  {
    height: 272px;
    width: 100%;
    background: url(/wp-content/themes/interstride/img/masterclass/modules.png);
    background-size: auto 100%;
    animation: scrollBackground 25s linear infinite; 
}

@keyframes scrollBackground {
    0% {
        background-position: 0 0;
    }
    100% {
        background-position: -2323px 0; 
    }
}