@keyframes swirl {
  from { transform: rotate(0deg) translateX(150px) rotate(0deg); }
  to { transform: rotate(360deg) translateX(150px) rotate(-360deg); }
}
#constraints 
{
  height: 400px;
  width: 400px;
  border: 1px solid black;
}

#square 
{
  top: 175px;
  left: 175px;
  position: relative;
  height: 50px;
  width: 50px;
  background: blue;
  -webkit-animation: swirl 4s linear infinite;
  animation-play-state: running;
}