a.back-to-top{display:none;width:60px;height:60px;text-indent:-9999px;position:fixed;z-index:999;right:20px;bottom:20px;background:rgba(117,162,30,0.5) url("arrow-up.png") no-repeat center 50%;background-size:40px 30px;-webkit-border-radius:20px;-moz-border-radius:20px;border-radius:20px}a.back-to-top:hover{background:rgba(100,140,30,0.5) url("arrow-up.png") no-repeat center 50%;background-size:40px 30px}