public-web/layouts/partials/language-selector.html

<h2 class="sr-only">{{ i18n "lang_select_title" }}</h2>
<nav>
  {{ if .IsTranslated -}}
    {{ range .Translations }}
      {{ partial "language-link.html" (dict
        "href" .RelPermalink
        "code" .Language.Params.LanguageCode
        "name" .Language.LanguageName
      ) }}
    {{ end -}}
  {{ else -}}
    {{ range site.Languages -}}
      {{ if ne site.Language.Lang .Lang }}
        {{ partial "language-link.html" (dict
          "href" (.Lang | relURL)
          "code" (.Params.LanguageCode | default .Lang)
          "name" .LanguageName
        ) }}
      {{ end -}}
    {{ end -}}
  {{ end -}}
</nav>