{% set href = pathto(root_doc) %}
<nav>
  <ul class="bd-navbar-elements navbar-nav">
        <li class="nav-item ">
            <a class="nav-link nav-external" href="https://docs.esmvaltool.org/en/latest/index.html">
             ESMValTool
            </a>
        </li>
        <li class="nav-item current active">
            <a class="nav-link nav-internal" href="{{ href }}">
            {{ (" ESMValCore ") }}
            </a>
        </li>
        <li class="nav-item ">
            <a class="nav-link nav-external" href="https://tutorial.esmvaltool.org/">
            Tutorial
            </a>
        </li>
        <li class="nav-item ">
            <a class="nav-link nav-external" href="https://esmvaltool.org/">
            Website
            </a>
        </li>
  </ul>
</nav>