Fullscreen Fading Slideshow with Pure Html / CSS

A pure HTML / CSS approach to creating a responsive fullscreen background slideshow that uses CSS3 animations for cross-fade transition effects.

How to use it:

Create a list of slides for the slideshow.

<ul class="slideshow">
  <li> <span>Slide One</span> </li>
  <li> <span>Slide Two</span> </li>
  <li> <span>Slide Three</span> </li>
  <li> <span>Slide Four</span> </li>
</ul>

Style the slideshow.

html { min-height: 100%; }
body { height: 100%; }
.slideshow {
  list-style: none;
  z-index: 1;
}
.slideshow li span {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0px;
  left: 0px;
  color: transparent;
  background-size: cover;
  background-position: 50% 50%;
  background-repeat: none;
  opacity: 0;
  z-index: 0;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  -webkit-animation: imageAnimation 24s linear infinite 0s;
  -moz-animation: imageAnimation 24s linear infinite 0s;
  animation: imageAnimation 24s linear infinite 0s;
}
.no-cssanimations .slideshow li span { opacity: 1; }

Create the crossfade animations by changing the opacity level using @keyframes.

@-webkit-keyframes 
imageAnimation { 0% {
 opacity: 0;
 -webkit-animation-timing-function: ease-in;
}
 12.5% {
 opacity: 1;
 -webkit-animation-timing-function: ease-out;
}
 25% {
 opacity: 1;
}
 37.5% {
 opacity: 0;
}
 100% {
 opacity: 0;
}
}
@-moz-keyframes 
imageAnimation { 0% {
 opacity: 0;
 -moz-animation-timing-function: ease-in;
}
 12.5% {
 opacity: 1;
 -moz-animation-timing-function: ease-out;
}
 25% {
 opacity: 1;
}
 37.5% {
 opacity: 0;
}
 100% {
 opacity: 0;
}
}
@keyframes 
imageAnimation { 0% {
 opacity: 0;
 -webkit-animation-timing-function: ease-in;
 -moz-animation-timing-function: ease-in;
 animation-timing-function: ease-in;
}
 12.5% {
 opacity: 1;
 -webkit-animation-timing-function: ease-out;
 -moz-animation-timing-function: ease-out;
 animation-timing-function: ease-out;
}
 25% {
 opacity: 1;
}
 37.5% {
 opacity: 0;
}
 100% {
 opacity: 0;
}
}
@-webkit-keyframes 
titleAnimation { 0% {
 opacity: 0;
}
 12.5% {
 opacity: 1;
}
 25% {
 opacity: 1;
}
 37.5% {
 opacity: 0;
}
 100% {
 opacity: 0;
}
}
@-moz-keyframes 
titleAnimation { 0% {
 opacity: 0;
}
 12.5% {
 opacity: 1;
}
 25% {
 opacity: 1;
}
 37.5% {
 opacity: 0;
}
 100% {
 opacity: 0;
}
}
@keyframes 
titleAnimation { 0% {
 opacity: 0;
}
 12.5% {
 opacity: 1;
}
 25% {
 opacity: 1;
}
 37.5% {
 opacity: 0;
}
 100% {
 opacity: 0;
}
}

Add background images to the slideshow.

.slideshow li:nth-child(1) span { background-image: url(1.jpg); }
.slideshow li:nth-child(2) span {
  background-image: url(2.jpg);
  -webkit-animation-delay: 6s;
  -moz-animation-delay: 6s;
  animation-delay: 6s;
}
.slideshow li:nth-child(3) span {
  background-image: url(3.jpg);
  -webkit-animation-delay: 12s;
  -moz-animation-delay: 12s;
  animation-delay: 12s;
}
.slideshow li:nth-child(4) span {
  background-image: url(4.jpg);
  -webkit-animation-delay: 18s;
  -moz-animation-delay: 18s;
  animation-delay: 18s;
}