contributor_side_nav.html

<div class="col-md-3 get-started-cloud-sidebar">
  <div class="sticky-top">
    <ul id="get-started-contributor-sidebar-list">
      {% assign past_issues = site.past_issues | sort_natural: "date" | reverse %}

      {% for item in past_issues %}
        {% assign currentdate = item.date | date: "%B %Y" %}
        {% if currentdate != date %}
          {% assign date = currentdate %}
        {% endif %}

        <ul>
          <li><a href="#issue-{{ item.issue }}">{{ date }}</a></li>
        </ul>
      {% endfor %}
    </ul>
  </div>
</div>

<script>

  $("#get-started-contributor-sidebar-list li a").on("click", function(e) {
    var href = $(this).attr("href")
    $('html, body').stop().animate({
      scrollTop: $(href).offset().top - 100
    }, 850);
    (e).preventDefault;
  });

  var lastId,
    topMenu = $("#get-started-contributor-sidebar-list"),
    topMenuHeight = topMenu.outerHeight() + 1,
    // All sidenav items
    menuItems = topMenu.find("a"),
  // Anchors for menu items
    scrollItems = menuItems.map(function() {
      var item = $(this).attr("href");
      if (item.length) { return item; }
  });

  $(window).scroll(function(){
    var fromTop = $(this).scrollTop()+topMenuHeight;
    var article = '.pytorch-article'

    $(article).each(function(i){
      var offsetScroll = $(this).offset().top-$(window).scrollTop();
      if (offsetScroll <= topMenuHeight + 200 && offsetScroll >= topMenuHeight - 200 && scrollItems[i] == "#" + $(this).children().attr("id") && $(".hidden:visible")) {
        $(menuItems).removeClass("active");
        $(menuItems[i]).addClass("active");
      }
    })
  });

</script>
<script src="https://code.jquery.com/jquery-migrate-3.0.0.min.js"></script>