{{- /* markdown-it built anchors that kept punctuation goldmark strips, so a heading whose id
       changed also carries its previous one as an empty target. data/anchor_aliases.json maps
       content path -> current anchor -> previous anchor. */ -}}
{{- $legacy := "" -}}
{{- with .Page.File -}}
  {{- with index (hugo.Data.anchor_aliases | default dict) .Path -}}
    {{- $legacy = index . $.Anchor -}}
  {{- end -}}
{{- end -}}
{{- with $legacy }}<span id="{{ . }}" class="legacy-anchor"></span>
{{ end -}}
<h{{ .Level }} id="{{ .Anchor }}">{{ .Text }}</h{{ .Level }}>