main{
    height: 303px;
    width: 513px;
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    margin: auto;
    border: 5px solid red;
    overflow: hidden;
}
main>section{
    height: 100%;
    width: 400%;
    display: flex;
    flex-direction: row;
    animation-name: slider;
    animation-duration: 10s;
    animation-iteration-count: infinite;
    animation-direction: alternate;
}
main>section>div{
    width: 100%;
}

section>div:nth-child(1){
    background: url("../images/image1.jpg");
    background-size: cover;
    background-position: center;
}
section>div:nth-child(2){
    background: url("../images/image2.jpg");
    background-size: cover;
    background-position: center;
}
section>div:nth-child(3){
    background: url("../images/image3.jpg");
    background-size: cover;
    background-position: center;
}
section>div:nth-child(4){
    background: url("../images/image4.jpg");
    background-size: cover;
    background-position: center;
}
@keyframes slider {
    0%,15%{
        transform: translateX(0);
    }
    25%,40%{
        transform: translateX(-25%);
    }
    50%,70%{
        transform: translateX(-50%);
    }
    80%,100%{
        transform: translateX(-75%);
    }
}