footer .top {
  font-size: 17px;
  line-height: 40px;
  position: fixed;
  bottom: 0px; right:20px;  /* ��惩𢰧�� */

   opacity: 0.5;
   filter: alpha(opacity=50); /* For IE8 and earlier */
  width: 40px;
  height: 40px;
  text-align: center;
  color: #000000;
  font-weight: bold;
  z-index: 9999;
  margin-bottom: 10px;
  
   } 
footer .top:hover {
  background-color:#505050; color: #ffffff;
  width: 40px;
  height: 40px;  line-height: 40px;
  font-weight: bold;
  }