p#back-to-top{
      position:fixed;
      bottom:100px;
      right:5px;
	  z-index:1000000
}
p#back-to-top a{
      text-align:center;
      text-decoration:none;
      color:#d1d1d1;
      display:block;
      width:50px;
      /*使用CSS3中的transition属性给跳转链接中的文字添加渐变效果*/
      -moz-transition:color 1s;
      -webkit-transition:color 1s;
      -o-transition:color 1s;
}
p#back-to-top a:hover{
      color:#979797;
}
p#back-to-top a span{
      background:#333 url(../images/arrow-up.png) no-repeat center center;
      border-radius:6px;
      display:block;
      height:50px;
      width:50px;
      margin-bottom:5px;
      /*使用CSS3中的transition属性给<span>标签背景颜色添加渐变效果*/
      -moz-transition:background 1s;
      -webkit-transition:background 1s;
      -o-transition:background 1s;
}
#back-to-top a:hover span{
      background:#4585F1 url(../images/arrow-up.png) no-repeat center center;
}