<div></div>

div {
  position: absolute;
  top: 0;
  left: 0;
  height: 8px;
  width: 8px;
  background-color: red;
  animation: move1, move2;
  animation-duration: 1s;
  animation-delay: 0s;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

@keyframes move1 {
  from {
    transform: translate3d(0px, 0px, 0);
  }
  to {
    transform: translate3d(0px, 200px, 0);
  }
}

@keyframes move2 {
  from {
    transform: translate3d(0px, 0px, 0);
  }
  to {
    transform: translate3d(200px, 0px, 0);
  }
}