<ul class="list-inline text-center filter-controls mb-4"> <li class="list-inline-item m-3 text-uppercase active" data-filter="all">Alle</li> {{ $categories := slice }} {{ range .Data.Pages }} {{ $categories = $categories | append .Params.category }} {{ end }} {{ range ( $categories | uniq ) }} <li class="list-inline-item m-3 text-uppercase" data-filter="{{ . | urlize }}">{{ . | humanize }}</li> {{ end }} </ul>