@keyframes move {
  0% { left: 0; }
  100% { left: 100%; }
}

.train {
  --d: 8s;
  content: "choo-choo";
  animation: move var(--d);
}

#Japan .train {
  animation-duration:
    calc(var(--d) * 0.5);
}

#USA .train {
  animation-duration:
    calc(var(--d) * 1.5);
}

#Iceland .train {
  display: none;
}

#UK .train {
  animation-delay: 2s;
  animation-play-state: paused;
}