.scroll_bg {
    background: #0F0;
    position: absolute;
    z-index: 999;
    right: 0;
    display: none;
}

    .scroll_bg .scroll_tiao {
        height: 10px;
        background: #F00;
        z-index: 1000;
        width: 100%;
        position: absolute;
        left: 0;
        top: 0;
    }