CSS Only Cross-fading Image Slideshow

A simple image slideshow implemented in pure CSS that allows the user to switch between images with a cross-fading effect based on CSS opacity, transition and transform properties.

How to use it:

Add as many images to the slideshow following the HTML structure as these:

<div class="carousel">
  <input type="radio" id="carousel-1" name="carousel" checked>
  <input type="radio" id="carousel-2" name="carousel">
  <input type="radio" id="carousel-3" name="carousel">
  <input type="radio" id="carousel-4" name="carousel">
  <input type="radio" id="carousel-5" name="carousel">
  <ul class="carousel__items">
      <li class="carousel__item"><img src="1.jpg" alt=""></li>
      <li class="carousel__item"><img src="2.jpg" alt=""></li>
      <li class="carousel__item"><img src="3.jpg" alt=""></li>
      <li class="carousel__item"><img src="4.jpg" alt=""></li>
      <li class="carousel__item"><img src="5.jpg" alt=""></li>
  </ul>
  <div class="carousel__prev">
      <label for="carousel-1"></label>
      <label for="carousel-2"></label>
      <label for="carousel-3"></label>
      <label for="carousel-4"></label>
      <label for="carousel-5"></label>
  </div>
  <div class="carousel__next">
      <label for="carousel-1"></label>
      <label for="carousel-2"></label>
      <label for="carousel-3"></label>
      <label for="carousel-4"></label>
      <label for="carousel-5"></label>
  </div>
  <div class="carousel__nav">
      <label for="carousel-1"></label>
      <label for="carousel-2"></label>
      <label for="carousel-3"></label>
      <label for="carousel-4"></label>
      <label for="carousel-5"></label>
  </div>
</div>

The required CSS styles for the slideshow. Just copy and insert the CSS snippets into your document and the carousel works.

.carousel > input[type="radio"]:nth-child(1):checked ~ .carousel__prev > label:nth-child(5), .carousel > input[type="radio"]:nth-child(1):checked ~ .carousel__next > label:nth-child(2), .carousel > input[type="radio"]:nth-child(2):checked ~ .carousel__prev > label:nth-child(1), .carousel > input[type="radio"]:nth-child(2):checked ~ .carousel__next > label:nth-child(3), .carousel > input[type="radio"]:nth-child(3):checked ~ .carousel__prev > label:nth-child(2), .carousel > input[type="radio"]:nth-child(3):checked ~ .carousel__next > label:nth-child(4), .carousel > input[type="radio"]:nth-child(4):checked ~ .carousel__prev > label:nth-child(3), .carousel > input[type="radio"]:nth-child(4):checked ~ .carousel__next > label:nth-child(5), .carousel > input[type="radio"]:nth-child(5):checked ~ .carousel__prev > label:nth-child(4), .carousel > input[type="radio"]:nth-child(5):checked ~ .carousel__next > label:nth-child(1) {
  opacity: 1 !important;
  z-index: 3;
}
.carousel {
  width: 100%;
  position: relative;
  overflow: hidden;
}
.carousel > input[type="radio"] {
  position: absolute;
  left: 0;
  opacity: 0;
  top: 0;
}
.carousel > input[type="radio"]:checked ~ .carousel__items .carousel__item, .carousel > input[type="radio"]:checked ~ .carousel__prev > label, .carousel > input[type="radio"]:checked ~ .carousel__next > label { opacity: 0; }
.carousel > input[type="radio"]:nth-child(1):checked ~ .carousel__items .carousel__item:nth-child(1) { opacity: 1; }
.carousel > input[type="radio"]:nth-child(1):checked ~ .carousel__nav > label:nth-child(1) {
  background: #ccc;
  cursor: default;
  pointer-events: none;
}
.carousel > input[type="radio"]:nth-child(2):checked ~ .carousel__items .carousel__item:nth-child(2) { opacity: 1; }
.carousel > input[type="radio"]:nth-child(2):checked ~ .carousel__nav > label:nth-child(2) {
  background: #ccc;
  cursor: default;
  pointer-events: none;
}
.carousel > input[type="radio"]:nth-child(3):checked ~ .carousel__items .carousel__item:nth-child(3) { opacity: 1; }
.carousel > input[type="radio"]:nth-child(3):checked ~ .carousel__nav > label:nth-child(3) {
  background: #ccc;
  cursor: default;
  pointer-events: none;
}
.carousel > input[type="radio"]:nth-child(4):checked ~ .carousel__items .carousel__item:nth-child(4) { opacity: 1; }
.carousel > input[type="radio"]:nth-child(4):checked ~ .carousel__nav > label:nth-child(4) {
  background: #ccc;
  cursor: default;
  pointer-events: none;
}
.carousel > input[type="radio"]:nth-child(5):checked ~ .carousel__items .carousel__item:nth-child(5) { opacity: 1; }
.carousel > input[type="radio"]:nth-child(5):checked ~ .carousel__nav > label:nth-child(5) {
  background: #ccc;
  cursor: default;
  pointer-events: none;
}
.carousel__items {
  margin: 0;
  padding: 0;
  list-style-type: none;
  width: 100%;
  height: 600px;
  position: relative;
}
.carousel__item {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
  -o-transition: opacity 2s;
  transition: opacity 2s;
  -webkit-transition: opacity 2s;
}
.carousel__item img {
  width: 100%;
  vertical-align: middle;
}
.carousel__prev > label, .carousel__next > label {
  border: 1px solid #fff;
  border-radius: 50%;
  cursor: pointer;
  display: block;
  width: 40px;
  height: 40px;
  position: absolute;
  top: 50%;
  -ms-transform: translateY(-50%);
  transform: translateY(-50%);
  -webkit-transform: translateY(-50%);
  -o-transition: all .3s ease;
  transition: all .3s ease;
  -webkit-transition: all .3s ease;
  opacity: 0;
  z-index: 2;
}
.carousel__prev > label:hover, .carousel__prev > label:focus, .carousel__next > label:hover, .carousel__next > label:focus { opacity: .5 !important; }
.carousel__prev > label:before, .carousel__prev > label:after, .carousel__next > label:before, .carousel__next > label:after {
  content: "";
  position: absolute;
  width: inherit;
  height: inherit;
}
.carousel__prev > label:before, .carousel__next > label:before {
  background: -webkit-gradient(linear, left bottom, left top, from(#fff), color-stop(10%, #fff), color-stop(10%, rgba(51, 51, 51, 0))),  -webkit-gradient(linear, right top, left top, from(#fff), color-stop(10%, #fff), color-stop(10%, rgba(51, 51, 51, 0)));
  background: -webkit-linear-gradient(bottom, #fff 0%, #fff 10%, rgba(51, 51, 51, 0) 10%),  -webkit-linear-gradient(right, #fff 0%, #fff 10%, rgba(51, 51, 51, 0) 10%);
  background: -o-linear-gradient(bottom, #fff 0%, #fff 10%, rgba(51, 51, 51, 0) 10%),  -o-linear-gradient(right, #fff 0%, #fff 10%, rgba(51, 51, 51, 0) 10%);
  background: linear-gradient(to top, #fff 0%, #fff 10%, rgba(51, 51, 51, 0) 10%),  linear-gradient(to left, #fff 0%, #fff 10%, rgba(51, 51, 51, 0) 10%);
  width: 60%;
  height: 60%;
  top: 20%;
}
.carousel__prev > label { left: 2%; }
.carousel__prev > label:before {
  left: 35%;
  top: 20%;
  -ms-transform: rotate(135deg);
  transform: rotate(135deg);
  -webkit-transform: rotate(135deg);
}
.carousel__next > label { right: 2%; }
.carousel__next > label:before {
  left: 10%;
  -ms-transform: rotate(315deg);
  transform: rotate(315deg);
  -webkit-transform: rotate(315deg);
}
.carousel__nav {
  position: absolute;
  bottom: 3%;
  left: 0;
  text-align: center;
  width: 100%;
  z-index: 3;
}
.carousel__nav > label {
  border: 1px solid #fff;
  display: inline-block;
  border-radius: 50%;
  cursor: pointer;
  margin: 0 .125%;
  width: 20px;
  height: 20px;
}