div {

  width: 50px;

  height: 50px;

  background: darkblue;

  position: relative;

  -webkit-animation-name: move-around; 

  -webkit-animation-duration: 5s; 

  -webkit-animation-timing-function: linear;

  -webkit-animation-iteration-count: infinite;

  -webkit-animation-direction: alternate;

}

​

@-webkit-keyframes move-around {

  0% { top: 0; left 0; }

  25% { top: 0; left: 200px; }

  50% { top: 200px; left: 200px}

  75% { top: 200px; left: 0px; }

  100% { top: 0; left: 0; }

}

​