Space animation css

selector {
-webkit-animation: scrolling 3s ease infinite;
   -moz-animation: scrolling 3s ease infinite;
   -o-animation: scrolling 3s  ease infinite;
   animation: scrolling 3s ease infinite;
}

@keyframes scrolling {
  0% {
    transform: translate(0);
  }
 
  50% {
    transform: translate(0,40px);
}

 
  100% {
     transform: translate(0);
  }
}