Image accordion slider (pure CSS)

<div class="container">
  <div class="item">
    <div class="photo">
      <img alt="photo 1" class="background-photo" src="https://images.unsplash.com/photo-1462275646964-a0e3386b89fa?ixlib=rb-1.2.1&amp;ixid=eyJhcHBfaWQiOjEyMDd9&amp;auto=format&amp;fit=crop&amp;w=800&amp;q=80"></div>
    <div class="overlay">

    </div>
    <div class="title">
      <h3 class="main-title">Spring</h3>
      <h4 class="subtitle">A flower blossoms for its own joy.
      </h4>
    </div>
  </div>
  <div class="item">
    <div class="photo"><img alt="Photo 2" class="background-photo" src="https://images.unsplash.com/photo-1491929007750-dce8ba76e610?ixlib=rb-1.2.1&amp;ixid=eyJhcHBfaWQiOjEyMDd9&amp;auto=format&amp;fit=crop&amp;w=747&amp;q=80"></div>
    <div class="overlay"></div>
    <div class="title">
      <h3 class="main-title">Summer</h3>
      <h4 class="subtitle">Every summer has a story.</h4>
    </div>
  </div>
  <div class="item">
    <div class="photo"><img alt="Photo 3" class="background-photo" src="https://images.unsplash.com/photo-1459478309853-2c33a60058e7?ixlib=rb-1.2.1&amp;ixid=eyJhcHBfaWQiOjEyMDd9&amp;auto=format&amp;fit=crop&amp;w=750&amp;q=80"></div>
    <div class="overlay"></div>
    <div class="title">
      <h3 class="main-title">fall</h3>
      <h4 class="subtitle">Life starts all over when it gets crisp in the fall.</h4>
    </div>
  </div>
  <div class="item">
    <div class="photo"><img alt="Photo 4" class="background-photo" src="https://images.unsplash.com/photo-1457269449834-928af64c684d?ixlib=rb-1.2.1&amp;ixid=eyJhcHBfaWQiOjEyMDd9&amp;auto=format&amp;fit=crop&amp;w=667&amp;q=80"></div>
    <div class="overlay"></div>
    <div class="title">
      <h3 class="main-title">winter</h3>
      <h4 class="subtitle">When snow falls, nature listens.</h4>
    </div>
  </div>
</div>