<div class="docs-nav-mobile unit whole show-on-mobiles">
  <select onchange="if (this.value) window.location.href=this.value">
    <option value="">Navigate the tutorials…</option>
    {% for section in site.data.tutorials -%}
    <optgroup label="{{ section.title }}">
      {% for item in section.tutorials -%}
        {% assign item_url = item | prepend:"/tutorials/" | append:"/" -%}
        {% assign tutorial = site.tutorials | where: "url", item_url | first -%}
        <option value="{{ tutorial.url | relative_url }}">{{ tutorial.title }}</option>
      {% endfor -%}
    </optgroup>
    {% endfor -%}
  </select>
</div>