#shape {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  background-color: white;
  animation: shape 2s linear infinite;
}

@keyframes shape {
  0% {
    border-radius: 50%;
    background-color: white;
  }
  50% {
    border-radius: 0%;
    background-color: white;
  }
  100% {
    border-radius: 0%;
    background-color: black;
  }
}