.slider {
    width: 75vw;
    height: auto;
    margin: auto;
    overflow: hidden;
}

.slider .slide-track {
    display: flex;
    animation: scroll 50s linear infinite;
    -webkit-animation: scroll 50s linear infinite;
    width: calc(400px * 21);
}

.slider .slide {
    width: 400px;
}

.slider .slide img {
    width: 100%;
}

@keyframes scroll {
    0% {
        -webkit-transform: translateX(0);
        transform: translateX(0);
    }
    100% {
        -webkit-transform: translateX(calc(-200px * 16));
        transform: translateX(calc(-200px * 16));
    }
}