* {
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}

.container {
    width: 100%;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #eae8ff;
}

.transition-box {
    width: 80%;
    max-width: 720px;
    margin: auto;
    background-image: url(background_change_img/background.png);
    background-position: center;
    overflow: hidden;
    line-height: 0;
    position: relative;
}


.img-wrap {
    position: absolute;
    width: 20px;
    top: 0;
    left: 0;
    overflow: hidden;
}

span {
    width: 1px;
    height: 100%;
    cursor: ew-resize;
    background: #fff;
    position: absolute;
    left: 20px;
    top: 0;
}

.arrow {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 40px;
}