Pure HTML5 / CSS3 Cross-fading Slideshow

A responsive, fullscreen background slideshow with a cross-fade effect, built with HTML5 and CSS3. No any JavaScript required.

How to use it:

Add custom content together with background images and navigation controls to the slideshow.

<div class="container">
  
  <div data-am-gallery="3 next-prev-navigation">
    <!-- Radio -->
    <input type="radio" name="gallery" id="img-1" checked />
    <input type="radio" name="gallery" id="img-2" />
    <input type="radio" name="gallery" id="img-3" />
    <!-- Images -->
    <div class="images">
      <div class="image" style="background-image: url(1.jpg);">
        <!-- Add content to images -->
        </div>
      </div>
      <div class="image" style="background-image: url(2.jpg);"></div>
      <div class="image" style="background-image: url(3.jpg"></div>
    </div>
    <!-- Navigation -->
    <div class="navigation">
      <label class="dot" for="img-1"></label>
      <label class="dot" for="img-2"></label>
      <label class="dot" for="img-3"></label>
    </div>
    
    <!-- Prev next navigation -->
    <div class="prev-container">
      <label class="prev" for="img-1"></label>
      <label class="prev" for="img-2"></label>
      <label class="prev" for="img-3"></label>
    </div>
    <div class="next-container">
      <label class="next" for="img-1"></label>
      <label class="next" for="img-2"></label>
      <label class="next" for="img-3"></label>
    </div>
  </div>
  
</div>

The primary CSS/CSS3 styles for the slideshow and its controls.

[data-am-gallery] {
 position: relative;
 width: 100%;
 height: 100%;
 background-color: #fff;
}
[data-am-gallery] .image {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  opacity: 0;
  -webkit-transition: opacity 1000ms ease;
  transition: opacity 1000ms ease;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
}
[data-am-gallery] input[type="radio"] {
  position: fixed;
  top: -9999px;
}
[data-am-gallery] input[type="radio"]:checked { /* This loop handles the image switching and dot active state */
}
[data-am-gallery] input[type="radio"]:checked:nth-child(5) ~ .images .image:nth-child(5) { opacity: 1; }
[data-am-gallery] input[type="radio"]:checked:nth-child(5) ~ .navigation .dot:nth-child(5) { background-color: coral; }
[data-am-gallery] input[type="radio"]:checked:nth-child(5) ~ .navigation .dot:nth-child(5):hover { opacity: 1; }
[data-am-gallery] input[type="radio"]:checked:nth-child(4) ~ .images .image:nth-child(4) { opacity: 1; }
[data-am-gallery] input[type="radio"]:checked:nth-child(4) ~ .navigation .dot:nth-child(4) { background-color: coral; }
[data-am-gallery] input[type="radio"]:checked:nth-child(4) ~ .navigation .dot:nth-child(4):hover { opacity: 1; }
[data-am-gallery] input[type="radio"]:checked:nth-child(3) ~ .images .image:nth-child(3) { opacity: 1; }
[data-am-gallery] input[type="radio"]:checked:nth-child(3) ~ .navigation .dot:nth-child(3) { background-color: coral; }
[data-am-gallery] input[type="radio"]:checked:nth-child(3) ~ .navigation .dot:nth-child(3):hover { opacity: 1; }
[data-am-gallery] input[type="radio"]:checked:nth-child(2) ~ .images .image:nth-child(2) { opacity: 1; }
[data-am-gallery] input[type="radio"]:checked:nth-child(2) ~ .navigation .dot:nth-child(2) { background-color: coral; }
[data-am-gallery] input[type="radio"]:checked:nth-child(2) ~ .navigation .dot:nth-child(2):hover { opacity: 1; }
[data-am-gallery] input[type="radio"]:checked:nth-child(1) ~ .images .image:nth-child(1) { opacity: 1; }
[data-am-gallery] input[type="radio"]:checked:nth-child(1) ~ .navigation .dot:nth-child(1) { background-color: coral; }
[data-am-gallery] input[type="radio"]:checked:nth-child(1) ~ .navigation .dot:nth-child(1):hover { opacity: 1; }
[data-am-gallery] .navigation {
  position: absolute;
  bottom: 15px;
  left: 50%;
  -webkit-transform: translateX(-50%);
  transform: translateX(-50%);
}
[data-am-gallery] .dot {
  display: inline-block;
  width: 15px;
  height: 15px;
  margin: 0 2px;
  border-radius: 50%;
  background-color: rgba(255, 255, 255, 0.8);
  cursor: pointer;
  -webkit-transition: opacity 200ms ease;
  transition: opacity 200ms ease;
}
[data-am-gallery] .dot:hover { opacity: 0.8; }
[data-am-gallery] .prev, [data-am-gallery] .next {
  position: absolute;
  display: none;
  top: 0;
  bottom: 0;
  width: 100px;
  cursor: pointer;
  -webkit-transition: all 200ms ease;
  transition: all 200ms ease;
  font-family: sans-serif;
}
[data-am-gallery] .prev:before, [data-am-gallery] .next:before {
  position: absolute;
  top: 50%;
  left: 50%;
  -webkit-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  font-size: 3vw;
  color: rgba(255, 255, 255, 0.5);
}
[data-am-gallery] .prev:hover, [data-am-gallery] .next:hover { background-color: rgba(255, 255, 255, 0.1); }
[data-am-gallery] .prev {
  left: 0;
  -webkit-transform: translateX(-100%);
  transform: translateX(-100%);
}
[data-am-gallery] .prev:before { content: "❮"; }
[data-am-gallery] .next {
  right: 0;
  -webkit-transform: translateX(100%);
  transform: translateX(100%);
}
[data-am-gallery] .next:before { content: "❯"; }
[data-am-gallery]:hover .prev {
  -webkit-transform: translateX(0);
  transform: translateX(0);
}
[data-am-gallery]:hover .next {
  -webkit-transform: translateX(0);
  transform: translateX(0);
}

The CSS loop to generate modifiers on [data-am-gallery] for number of images. This is required to handle the prev and next buttons.

[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(5) ~ .prev-container .prev:nth-child(4) { display: block; }
[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(5) ~ .next-container .next:nth-child(1) { display: block; }
[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(4) ~ .prev-container .prev:nth-child(3) { display: block; }
[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(4) ~ .next-container .next:nth-child(5) { display: block; }
[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(3) ~ .prev-container .prev:nth-child(2) { display: block; }
[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(3) ~ .next-container .next:nth-child(4) { display: block; }
[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(2) ~ .prev-container .prev:nth-child(1) { display: block; }
[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(2) ~ .next-container .next:nth-child(3) { display: block; }
[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(1) ~ .prev-container .prev:nth-child(5) { display: block; }
[data-am-gallery~="5"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(1) ~ .next-container .next:nth-child(2) { display: block; }
[data-am-gallery~="4"] input[type="radio"]:nth-child(5), [data-am-gallery~="4"] .navigation .dot:nth-child(5), [data-am-gallery~="4"] .image:nth-child(5) { display: none !important; }
[data-am-gallery~="4"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(4) ~ .prev-container .prev:nth-child(3) { display: block; }
[data-am-gallery~="4"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(4) ~ .next-container .next:nth-child(1) { display: block; }
[data-am-gallery~="4"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(3) ~ .prev-container .prev:nth-child(2) { display: block; }
[data-am-gallery~="4"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(3) ~ .next-container .next:nth-child(4) { display: block; }
[data-am-gallery~="4"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(2) ~ .prev-container .prev:nth-child(1) { display: block; }
[data-am-gallery~="4"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(2) ~ .next-container .next:nth-child(3) { display: block; }
[data-am-gallery~="4"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(1) ~ .prev-container .prev:nth-child(4) { display: block; }
[data-am-gallery~="4"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(1) ~ .next-container .next:nth-child(2) { display: block; }
[data-am-gallery~="3"] input[type="radio"]:nth-child(5), [data-am-gallery~="3"] .navigation .dot:nth-child(5), [data-am-gallery~="3"] .image:nth-child(5) { display: none !important; }
[data-am-gallery~="3"] input[type="radio"]:nth-child(4), [data-am-gallery~="3"] .navigation .dot:nth-child(4), [data-am-gallery~="3"] .image:nth-child(4) { display: none !important; }
[data-am-gallery~="3"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(3) ~ .prev-container .prev:nth-child(2) { display: block; }
[data-am-gallery~="3"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(3) ~ .next-container .next:nth-child(1) { display: block; }
[data-am-gallery~="3"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(2) ~ .prev-container .prev:nth-child(1) { display: block; }
[data-am-gallery~="3"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(2) ~ .next-container .next:nth-child(3) { display: block; }
[data-am-gallery~="3"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(1) ~ .prev-container .prev:nth-child(3) { display: block; }
[data-am-gallery~="3"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(1) ~ .next-container .next:nth-child(2) { display: block; }
[data-am-gallery~="2"] input[type="radio"]:nth-child(5), [data-am-gallery~="2"] .navigation .dot:nth-child(5), [data-am-gallery~="2"] .image:nth-child(5) { display: none !important; }
[data-am-gallery~="2"] input[type="radio"]:nth-child(4), [data-am-gallery~="2"] .navigation .dot:nth-child(4), [data-am-gallery~="2"] .image:nth-child(4) { display: none !important; }
[data-am-gallery~="2"] input[type="radio"]:nth-child(3), [data-am-gallery~="2"] .navigation .dot:nth-child(3), [data-am-gallery~="2"] .image:nth-child(3) { display: none !important; }
[data-am-gallery~="2"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(2) ~ .prev-container .prev:nth-child(1) { display: block; }
[data-am-gallery~="2"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(2) ~ .next-container .next:nth-child(1) { display: block; }
[data-am-gallery~="2"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(1) ~ .prev-container .prev:nth-child(2) { display: block; }
[data-am-gallery~="2"][data-am-gallery~="next-prev-navigation"] input[type="radio"]:checked:nth-child(1) ~ .next-container .next:nth-child(2) { display: block; }
[data-am-gallery~="1"] .navigation { display: none; }