site/docs/layouts/partials/menu.html

<div class="menu">
 <ul>
    {{- $currentNode := . }}
    {{- range .Site.Home.Sections.ByTitle}}
    {{- template "menu-loop" dict "sect" . "currentnode" $currentNode}}
    {{- end}}
</ul>
</div>

<!-- Template -->
{{- define "menu-loop" }}
{{- $currentNode := .currentnode }}
{{- with .sect}}
{{- if .IsSection }}
    {{- $numberOfPages := (add (len .Pages) (len .Sections)) }}
    <li>
        <a class="{{- if .IsAncestor $currentNode}} ancestor{{end}}
            {{- if eq .RelPermalink $currentNode.RelPermalink}} active{{end}}"
            href="{{.RelPermalink}}">{{.Title}}</h6></a>
      {{- if ne $numberOfPages 0 }}
        <ul class="
            {{- if .IsAncestor $currentNode}} ancestor{{end}}
            {{- if ne $numberOfPages 0 }} parent{{end}}
            ">
          {{- .Scratch.Set "pages" .Pages }}
          {{- if .Sections}}
          {{- .Scratch.Set "pages" (.Pages | union .Sections) }}
          {{- end}}
          {{- $pages := (.Scratch.Get "pages") }}

          {{- range $pages.ByTitle }}
            {{- template "menu-loop" dict "sect" . "currentnode" $currentNode }}
          {{- end}}
        </ul>
      {{- end}}
    </li>
{{- else}}
    <li>
             <a class="{{- if eq .RelPermalink $currentNode.RelPermalink}} active{{end}}" href="{{.RelPermalink}}"> {{.LinkTitle}} </a>
    </li>
{{- end}}
{{- end}}
{{- end}}