* {
  margin: 0;
  padding: 0;
}

*:focus {
  outline: none;
}

.btn {
  display: block;
  margin: 300px auto;
  width: 120px;
  height: 40px;
  background-color: #00B464;
  border: 0;
  
  color: #fff;
  border-radius: 6px;
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.btn i {
  
  position: absolute;
  width: 1px;
  height: 1px;
  border-radius: 50%;
  animation: kf 0.9s;
  animation-iteration-count: 1;
  transform-origin: 50% 50%
}

@keyframes kf {
  0% {
    background-color: #000;
    opacity: 0.3;
    transform: scale(0);
  }

  100% {
    transform: scale(200);
    opacity: 0;
  }

}