LeaveItFork/layouts/partials/toc.html

<div class="post-toc" id="post-toc">
  <h2 class="post-toc-title">{{ T "toc" }}</h2>
  {{ $globalAutoCollapseToc := .Site.Params.autoCollapseToc | default false }}
  <div class="post-toc-content{{ if not (or .Params.autoCollapseToc (and $globalAutoCollapseToc (ne .Params.autoCollapseToc false))) }} always-active{{ end }}">
    {{.TableOfContents}}
  </div>
</div>

<script type="text/javascript">
  window.onload = function () {
    var fix = $('.post-toc');
    var end = $('.post-comment');
    var fixTop = fix.offset().top, fixHeight = fix.height();
    var endTop, miss;
    var offsetTop = fix[0].offsetTop;

    $(window).scroll(function () {
      var docTop = Math.max(document.body.scrollTop, document.documentElement.scrollTop);

      if (end.length > 0) {
        endTop = end.offset().top;
        miss = endTop - docTop - fixHeight;
      }

      if (fixTop < docTop) {
        fix.css({ 'position': 'fixed' });
        if ((end.length > 0) && (endTop < (docTop + fixHeight))) {
          fix.css({ top: miss });
        } else {
          fix.css({ top: 0 });
        }
      } else {
        fix.css({ 'position': 'absolute' });
        fix.css({ top: offsetTop });
      }
    })
  }
</script>