<div class="slides">
  <div class="slide slide--active" data-slide="1">
    <h1>Slide 1</h1>
    <span class="btn" data-slide-btn="2">Button 1</span>
    <span class="btn" data-slide-btn="3">Button 2</span>
    <span class="btn" data-slide-btn="4">Button 3</span>
  </div>
  <div class="slide" data-slide="2">
    <h1>Slide 2</h1>
    <span class="btn js-slide-return-btn">return</span>
  </div>
  <div class="slide" data-slide="3">
    <h1>Slide 3</h1>
    <span class="btn js-slide-return-btn">return</span>
  </div>
  <div class="slide" data-slide="4">
    <h1>Slide 4</h1>
    <span class="btn js-slide-return-btn">return</span>
  </div>
</div>