px;
  background-color: lightblue;
  scroll-snap-align: start;
}

#inserted-snap-container {
  top: 400px;
  height: 600px;
  width: 400px;
  overflow: scroll;
  scroll-snap-type: y mandatory;
}
</style>

<div class="space"></div>
  <div id="middle-scroller">
    <div class="space"></div>
    <div id="inner-scroller">
        <div class="space"></div>
        <div id="inner-snap-area"></div>
    </div>
  </div>
</div>
<div id="document-snap-area"></div>
<script>

const inner_scroller = document.getElementBy