#totop{ width: 60px; height: 60px; background-color: #d7d7d7; position: fixed; _position: absolute; right: 0;
    top: 40%;opacity: .5; filter:alpha(opacity:50); overflow: hidden}
.tt-show{ display: block; width: 40px; padding: 10px; line-height: 20px; text-align: center; background-color: #ddd; height: 40px;}
.tt-xf{ display: block; width: 40px; position: absolute; left: 0; bottom: -60px;
    height: 40px; line-height: 20px; text-decoration: none; padding: 10px; 
    text-align: center; background-color: #000; color: #fff}
.tt-xf:hover{ color:#fff}
.tt-show2{ display: block; width: 40px; padding: 10px; line-height: 20px; text-align: center; background-color: #ddd; height: 40px;}
.tt-xf2{ display: block; width: 40px; position: absolute; left: 0; bottom: -100px;
    height: 40px; line-height: 20px; text-decoration: none; padding: 10px; 
    text-align: center; background-color: #000; color: #fff}
.tt-xf2:hover{ color:#fff}
.pr{ position: relative}