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>