up {
    border: 3px solid black;
    display: flex;
    width: 100px;
    height: 20px;
  }

  #scroller div {
    width: 100px;
    height: 100px;
  }

  #scroller div::scroll-marker {
    overflow: hidden;
    content: '';
    background-color: red;
    display: inline-flex;
    width: 10px;
    height: 10px;
    border-radius: 50%;
  }

  #scroller div::scroll-marker:target-current {
    background-color: green;
  }
</style>
<div id='scroller'>
  <div></div>
  <div id='target'></div>
</div>
<script>
  f