.banner {
    border: 4px solid black;
    width: 300px;
    height: 150px;
    box-sizing: content-box;
}

.banner .banner-wrapper {
    position: relative;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: -1;
}

.banner-list {
    width: 1200px;
    height: 100%;
    position: absolute;
    left: 0;
    top: 0;
    padding: 0;
    margin: 0;
    list-style: none;
}

.banner-list .item {
    width: 300px;
    height: 100%;
    display: inline-block;
    float: left;
    font-weight: bold;
    font-size: 40px;
    line-height: 150px;
}

.banner-list .item#item1 {
    background: #fee2b3;
}

.banner-list .item#item2 {
    background: #ffa299;
}

.banner-list .item#item3 {
    background: #ad6989;
}

.banner-list .item#item4 {
    background: #562349;
}


.banner .banner-wrapper {
    position: relative;
    width: 100%;
    height: 100%;
    overflow: hidden;
}

@keyframes banner-swipe {
    0% {
        left: 0;
    }

    33.33% {
        left: -300px;
    }

    66.66% {
        left: -600px;
    }

    100% {
        left: -900px;
    }
}

.banner-list {
    width: 1500px;
    height: 100%;
    position: absolute;
    left: 0;
    top: 0;
    padding: 0;
    margin: 0;
    list-style: none;
    animation: banner-swipe 10s ease-in infinite;
}