<center><button class="click" onclick="alert('Subscribe me on Twitter! My Twitter is @ExpertMan11')">CLICK TO ME!</button></center>

button.click{
  background-color:red;
  color:white;
  padding:30px;
  border-radius:5000px;
  border:none;
  font-size:50px;
  position: relative;
  animation:click 3s infinite;
}
@keyframes click{
  from{background-color:red;}
  to{background-color:blue;}
  0%   {top: 0px;}
  25%  {top: 200px;}
  50%  {top: 100px;}
  75%  {top: 200px;}
  100% {top: 0px;}
}