.btn{position:absolute;top:0;left:0;right:0;bottom:0;margin:auto;text-decoration:none;cursor:pointer;border:1px solid #1a1a1a;border-radius:8px;height:40px;width:10em;padding:0;outline:none;overflow:hidden;color:#1a1a1a;-webkit-transition:color .3s .1s ease-out;transition:color .3s .1s ease-out;text-align:center;line-height:40px;font-size:14px;text-shadow:none;z-index:1}
button.close{border:1px solid;opacity:.5;margin-top:60px}
button.close:hover,button.close:focus{opacity:.8}
.btn::before{position:absolute;top:0;left:0;right:0;bottom:0;margin:auto;content:'';border-radius:50%;display:block;width:20em;height:20em;line-height:20em;left:-5em;text-align:center;-webkit-transition:box-shadow .5s ease-out;transition:box-shadow .5s ease-out;z-index:-1}
.btn:hover{color:#fff}
.btn:hover::before{box-shadow:inset 0 0 0 10em #1a1a1a}
.btn:active{top:3px}