.btn4 a{position:relative;padding:15px 50px;display:block;text-decoration:none;text-transform:uppercase;width:200px;overflow:hidden;border-radius:40px;margin:auto}.btn4 a span{position:relative;color:#fff;font-size:20px;letter-spacing:2px;z-index:1}.btn4 a .liquid{position:absolute;top:-80px;left:0;width:200px;height:200px;background:#4973ff;box-shadow:inset 0 0 50px rgba(0,0,0,.5);transition:.5s}.btn4 a .liquid::after,.btn4 a .liquid::before{content:'';width:200%;height:200%;position:absolute;top:0;left:50%;transform:translate(-50%,-75%);background:#000}.btn4 a .liquid::before{border-radius:45%;background:rgba(20,20,20,1);animation:animate 5s linear infinite}.btn4 a .liquid::after{border-radius:40%;background:rgba(20,20,20,.5);animation:animate 10s linear infinite}.btn4 a:hover .liquid{top:-120px}@keyframes animate{0%{transform:translate(-50%,-75%) rotate(0deg)}100%{transform:translate(-50%,-75%) rotate(360deg)}}