#totop,#totop2{
    position: fixed;right: 0;bottom: 10px;
    width: 100px;height: 167px;overflow: hidden;
    cursor: pointer;display: none;
    background: url(up.png) no-repeat 0px 0;
    z-index: 9999;
}
#totop2{
    background: url(up.png) no-repeat -100px 0;
}