.ball {
  position: relative;
  left: calc(100% - 20rem);
  background-color: #ffb33a;
  width: 20rem;
  height: 20rem;
  border-radius: 10rem;
  animation: bounce 3s;
  animation-timing-function: cubic-bezier(0.5, -0.5, 0.5, 1.5);
  animation-iteration-count: infinite;
  animation-direction: alternate;
}

@keyframes bounce {
  
  0% {
    left: 0%;
  }
  
  100% {
    left: calc(100% - 20rem);
  }
  
}