overscroll-behavior

overscroll-behavior: auto;

overscroll-behavior: contain;

overscroll-behavior: none;

<section class="default-example" id="default-example">
  <div class="example-container">
    <div class="box">
      This is a scrollable container. Michaelmas term lately over, and the Lord
      Chancellor sitting in Lincoln's Inn Hall. Implacable November weather. As
      much mud in the streets as if the waters had but newly retired from the
      face of the earth.
      <br /><br />
      Lorem Ipsum has been the industry's standard dummy text ever since the
      1500s, when an unknown printer took a galley of type and scrambled it to
      make a type specimen book. It has survived not only five centuries, but
      also the leap into electronic typesetting, remaining essentially
      unchanged.
    </div>
    <div id="example-element">
      This is the inner container. Focus on this container, scroll to the bottom
      and when you reach the bottom keep scrolling.
      <p>
        If you have
        <code class="language-css">overscroll-behavior: auto;</code> selected
        the outer container will start to scroll.
      </p>
      If you have
      <code class="language-css">overscroll-behavior: contain;</code> selected,
      the outer container will not scroll unless you move your cursor out of the
      inner container and try to perform scroll on the outer container.
    </div>
  </div>
</section>

.example-container {
  width: 35em;
  height: 18em;
  border: medium dotted;
  padding: 0.75em;
  text-align: left;
  overflow: auto;
  display: flex;
}

.box {
  width: 50%;
}

#example-element {
  width: 50%;
  height: 12em;
  border: medium dotted #1b76c4;
  padding: 0.3em;
  margin: 0 0.3em;
  text-align: left;
  overflow: auto;
  overscroll-behavior: contain;
}

/* Keyword values */
overscroll-behavior: auto; /* default */
overscroll-behavior: contain;
overscroll-behavior: none;

/* Two values */
overscroll-behavior: auto contain;

/* Global values */
overscroll-behavior: inherit;
overscroll-behavior: initial;
overscroll-behavior: revert;
overscroll-behavior: revert-layer;
overscroll-behavior: unset;