.crossfade > figure {
  animation: imageAnimation 30s linear infinite 0s; 
  backface-visibility: hidden;
  background-size: cover;
  background-position: center center;
  color: transparent;
  height: 100%;
  left: 0px;
  opacity: 0;
  position: fixed;
  top: 0px;
  width: 100%;
  z-index: -9999999;
}

.crossfade > figure:nth-child(1) { background-image: url('../bg-images/1.jpg'); }

.crossfade > figure:nth-child(2) {
  animation-delay: 6s;
  background-image: url('../bg-images/2.jpg');
}

.crossfade > figure:nth-child(3) {
  animation-delay: 12s;
  background-image: url('../bg-images/3.jpg');
}

.crossfade > figure:nth-child(4) {
  animation-delay: 18s;
  background-image: url('../bg-images/4.jpg');
}

@keyframes 
imageAnimation {  0% {
 animation-timing-function: ease-in;
 opacity: 0;
}
 8% {
 animation-timing-function: ease-out;
 opacity: 1;
}
 17% {
 opacity: 1
}
 25% {
 opacity: 0
}
 100% {
 opacity: 0
}
}