.UIBackTopTopControl {
      background: rgba(0, 0, 0, 0) url(images/up.png) no-repeat scroll center center;
    z-index: 999999999;
    position: fixed;
    bottom: 55px;
    right: 100px;
    width: 64px;
    height: 64px;
    background-repeat: no-repeat;
    background-size: cover;
    opacity: .4;
}