"

From 2014.igem.org

/* UItoTop styles ========================================================*/

1. toTop {

 background: url(../images/totop.png) 0 0 no-repeat;
 border: none;
 bottom: 150px;
 display: none;
 height: 15px;
 left: 60%;
 margin-left: 500px;
 overflow: hidden;
 position: fixed;
 text-decoration: none;
 text-indent: -999px;
 width: 29px;
 z-index: 20;
 opacity: .7;
 -ms-filter: 'progid:DXImageTransform.Microsoft.Alpha(Opacity=70)';
 -webkit-transition: all 0.3s ease;
 transition: all 0.3s ease;

}

1. toTop:hover {

 background: url(../images/totop_hover.png) 0 0 no-repeat;
 opacity: 1;
 -ms-filter: 'progid:DXImageTransform.Microsoft.Alpha(Opacity=100)';

}