@keyframes noHW {
    0%   {left: 0;}
    100% {left: 400px;}
}

@keyframes HW {
  0% {transform: translate(0px, 0px);}
  100% {transform: translate(400px, 0px);}
}

#noHWAccel {
  animation: noHW 6s alternate infinite;
  height: 100px;
  width: 100px;
  position: relative;
  background-color: red;
  border: 10px solid white;
  box-sizing: border-box;
}

#HWAccel {
  animation: HW 6s alternate infinite;
  height: 100px;
  width: 100px;
  position: relative;
  background-color: blue;
  border: 10px solid white;
  box-sizing: border-box;
}