<nav>
  <!--
  <a href="/"
     {% if page.url == "/" %}style="color: red;"{% endif %}
     >Hauptseite</a>
  <a href="/about.html"
     {% if page.url == "/about.html" %}style="color: red;"{% endif %}
     >Über uns</a>
  -->
  {% for item in site.data.navigation %}
  <a href="{{ item.link }}"
     {% if page.url == item.link %}class="current-site"{% endif %}
     >{{ item.name }}</a>
  {% endfor %}
</nav>
