div#slider {width: 1400px; max-width: 1400px;}

div#slider figure {
  position: relative; 
  width: 5600px;
  margin: 0;
  padding: 0;
  font-size: 0;
  text-align: left;
}

div#slider figure img { width: 20%; height: auto; float: left; }

div#slider { width: 1400px; max-width: 1400px; height: 500px; overflow: hidden }

@keyframes slidy {
  0% { left: 0%; }
  20% { left: 0%; }
  25% { left: -100%; }
  45% { left: -100%; }
  50% { left: -200%; }
  70% { left: -200%; }
  75% { left: -300%; }
  95% { left: -300%; }
  100% { left: -400%; }
}

div#slider figure {
  position: relative;
  width: 5600px;
  margin: 0;
  padding: 0;
  font-size: 0;
  left: 0;
  text-align: left;
  animation: 30s slidy infinite;
}