.go-top-wrap .go-top-btn{background-color:#0a0}.go-top-wrap .go-top-btn:after{z-index:-1;content:"";position:absolute;left:0;top:0;width:40px;height:40px;-webkit-animation:ripple 1.6s ease-out infinite;animation:ripple 1.6s ease-out infinite;opacity:0;background:#0a0}.go-top-wrap .go-top-btn:hover{background-color:#000;color:#fff}