.move00 {
  position: relative;
  animation: myfirst1 40s;
  animation-iteration-count:infinite;
}

@keyframes myfirst1 {
 0% { transform : translateX(0px)}
 25% { transform : translateX(-250px)}
 50% { transform : translateX(0px)}
 75% { transform : translateX(250px)}
 100% { transform : translateX(0px)}