<div class="story-container">
  <div class="story-container__page-content story-scrollspy"></div>
  <button class="story-scrollspy-target1" data-scrollspy data-scrollspy-offset="400">
    This Button appears when the bottom of the red container reaches top when the viewport is scrolled 400px. It disappears when the viewport is scrolled back.
  </button>
  <button class="story-scrollspy-target2" data-scrollspy data-scrollspy-offset="600">
    This Button appears when the bottom of the blue container reaches top when the viewport is scrolled 600px. It disappears when the viewport is scrolled back.
  </button>
</div>
