#backTop{width:35px;height:35px;padding:10px;border-radius:4px;text-indent:-9999px;cursor:pointer;z-index:999999999;display:none;box-sizing:content-box;-webkit-box-sizing:content-box}#backTop.white{background:url(../img/uparr-48-b.png) no-repeat center center rgb(255 255 255 / .8);border:1px solid #ccc}#backTop.black{background:url(../img/uparr-48-w.png) no-repeat center center rgb(0 0 0 / .8);border:1px solid #ccc}#backTop.red{background:url(../img/uparr-48-w.png) no-repeat center center rgb(217 97 81 / .9);border:1px solid #fff}#backTop.green{background:url(../img/uparr-48-b.png) no-repeat center center rgb(81 217 187 / .9);border:1px solid #fff}