.train-car { background: transparent; }

/* Keep the newest cars in view. Older answers may leave the scene to the left. */
.train {
  justify-content: flex-end;
  overflow: hidden;
}

/* The page can still move when a very short screen needs it, without showing
   desktop scrollbars around the play area. */
html,
body,
.screen {
  scrollbar-width: none;
}

html::-webkit-scrollbar,
body::-webkit-scrollbar,
.screen::-webkit-scrollbar {
  display: none;
}

@keyframes depart {
  0% { transform: translateX(60vw); }
  35%, 65% { transform: translateX(0); }
  100% { transform: translateX(-65vw); }
}