hugo-labs/layouts/partials/sidebar.html

{{ $currentPage := . }}
<ul>
  {{ range .Site.Menus.main }}
    {{ if .HasChildren }}
      <li class="item {{ if $currentPage.IsMenuCurrent "main" . }}active{{ end }}"><a href="{{ .URL }}">{{ .Name }}</a>
        {{ if or ($currentPage.HasMenuCurrent "main" .) ($currentPage.IsMenuCurrent "main" .) }}
          <ul>
            {{ range .Children }}
              <li class="sub-item{{ if $currentPage.IsMenuCurrent "main" . }} active{{ end }}"><a href="{{ .URL }}">{{ .Name }}</a>
                {{ if or ($currentPage.HasMenuCurrent "main" .) ($currentPage.IsMenuCurrent "main" .) }}
                  <ul>
                    {{ range .Children }}
                      <li class="subsub-item{{ if $currentPage.IsMenuCurrent "main" . }} active{{ end }}"><a href="{{ .URL }}">{{ .Name }}</a>
                        {{ if or ($currentPage.HasMenuCurrent "main" .) ($currentPage.IsMenuCurrent "main" .) }}
                          <ul>
                            {{ range .Children }}
                              <li class="subsubsub-item{{ if $currentPage.IsMenuCurrent "main" . }} active{{ end }}"><a href="{{ .URL }}">{{ .Name }}</a></li>
                            {{ end }}
                          </ul>
                        {{ end }}
                      </li>        
                    {{ end }}
                  </ul>
                {{ end }}
              </li>
            {{ end }}
          </ul>
        {{ end }}
      </li>
    {{ end }}
  {{ end }}
</ul>