zdoc/layouts/partials/main/sections/single-menu.html

<div class="menu">
  <h6 class="menu__label">
    {{ if .IsHome }}
      {{ .Site.Title }}
    {{ else }}
      {{ $.Param "Title" }}
    {{ end }}
  </h6>
  <ul>
    {{ $root := . }}
    {{ range (.Site.GetPage "section" .Type).Pages }}
      {{ template "render-menu" (dict "ctx" . "root" $root "depth" 0)}}
    {{ end }}
  </ul>
</div>

{{ define "render-menu" }}
  {{ $root := .root }}
  {{ $ctx := .ctx }}
  {{ $depth := .depth }}
  {{ $currentURL := $root.Permalink }}
  
  {{ $sectionName1 := index (last 1 (split (delimit (split $ctx.Permalink "/") "," "") ",")) 0 }}
  {{ $sectionName2 := index (last 2 (split (delimit (split $currentURL "/") "," "") ",")) 0 }}

  {{ $active := in $currentURL $ctx.Permalink }}
  {{ $active = or $active (eq $sectionName1 $sectionName2) }}
  {{ $active = or $active (in $currentURL $sectionName1) }}
  
  {{ if $ctx.Params.Collapsible }}
  <li class="menu__title--collapse {{ if $active }}active{{ end }}" data-depth="{{ $depth }}" data-permalink="{{ $ctx.Permalink }}">
    <span class="menu__title--collapse-text">
      {{ $ctx.Title }}
    </span>
    <span class="menu__title--icon {{ if $active }}{{ if eq ($root.Param "languagedir") "rtl" }}downrtl{{ else }}down{{ end }}{{ else }}right{{ end }}">
      {{ if eq ($root.Param "languagedir") "rtl" }}
        {{ partial "svgs/arrow-left.svg" (dict "width" 22 "height" 22) }}
      {{ else }}
        {{ partial "svgs/arrow-right.svg" (dict "width" 22 "height" 22) }}
      {{ end }}
    </span>
  </li>
  <ul class="menu__list {{ if $active }}active{{ else if (in $ctx.Permalink (print "/" $sectionName1 "/")) }}{{ end }}" data-data={{ print "/" $sectionName1 "/"}} data-link={{ .root.Permalink }}>
    {{ range $ctx.Pages.ByWeight }}
      {{ if .Params.Collapsible }}
        {{ template "render-menu" (dict "ctx" . "root" $root "depth" (add $depth 1)) }}
      {{ else }}
        {{ $lastUrlElement1 := index (last 1 (split (delimit (split .Permalink "/") "," "") ",")) 0 }}
        {{ $lastUrlElement2 := index (last 1 (split (delimit (split $currentURL "/") "," "") ",")) 0 }}
        <li>
          <a href="{{ .Permalink }}" class="menu__title {{ if and (eq $lastUrlElement1 $lastUrlElement2) (eq $sectionName1 $sectionName2) }}active{{ end }}" data-depth="{{ $depth }}">{{ .Title }}</a>
        </li>
      {{ end }}
    {{ end }}
  </ul>
  {{ else }}
  {{ $lastUrlElement1 := index (last 1 (split (delimit (split $ctx.Permalink "/") "," "") ",")) 0 }}
  {{ $lastUrlElement2 := index (last 1 (split (delimit (split $currentURL "/") "," "") ",")) 0 }}
  <li class="{{ if $active }}active{{ end }}">
    <a href="{{ $ctx.Permalink }}"
      class="menu__title {{ if $active }}active{{ end }}">{{ $ctx.Title }}</a>
  </li>
  {{ end }}
{{ end }}