@import url('https://fonts.googleapis.com/css?family=Poppins:400,500,600,700&display=swap');
*{
  margin: 0;
  padding: 0;
  box-sizing: border-box;  
}

.btn a{
  position: relative;
  color: #f5f5f5;
  height: 60px;
  width: 150px;
  display: block;
  text-align: center;
  border-radius: 10px;
  text-decoration: none;
  background-image: linear-gradient(115deg,#4fcf70,#fad648,#a767e5,#12bcfe,#44ce7b);
}
.btn a:hover{
  animation: rotate 0.4s linear infinite;
}
@keyframes rotate {
  100%{
    filter: hue-rotate(-360deg)
  }
}
.btn a span{
  height: 88%;
  width: 96%;
  background: #111;
  display: block;
  position: absolute;
  top: 50%;
  left: 50%;
  border-radius: 6px;
  line-height: 55px;
  font-size:13px;
  transform: translate(-50%, -50%);
}