.parallax > use{
  animation:move-forever 12s linear infinite;
  &:nth-child(1){animation-delay:-2s;}
  &:nth-child(2){animation-delay:-2s; animation-duration:5s}
  &:nth-child(3){animation-delay:-4s; animation-duration:3s}
}


@keyframes move-forever{
  0%{transform: translate(-90px , 0%)}
  100%{transform: translate(85px , 0%)} 
}