title: Position "sticky" not working in ReactJS app, and no "overflow" attribute specified in parent
body: <p>I'm building a React app, and I'm having a problem with <code>position: sticky</code> in my <code>story-header</code> element. I already checked the parent styles and there's no <code>overflow: hidden</code> attribute-value. </p>
  
  <p>HTML</p>
  
  <pre><code>&lt;div className='StoryList' &gt;
      &lt;div className='story-header'&gt;&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>CSS - Stylesheet</p>
  
  <pre><code>.App {
      width: 100%;
      overflow: visible;
  }
  .StoryList {
      position: relative;
      margin: 0;
      width: 100%;
  }
  .story-header {
      width: 100%;
      top: -20px;
      height: 50px;
      left: 0;
      background-color: lightgray;
      position: sticky;
      z-index: 1;
  }
  </code></pre>
  
  <p><strong>Why is the <code>story-header</code> sliding above the top?</strong></p>