{{- $group := printf "tabs-%v" (default .Parent.Ordinal (.Parent.Get 0)) -}}
{{- $tab := printf "%s-%d" $group .Ordinal }}
<input type="radio" class="toggle" name="{{ $group }}" id="{{ $tab }}" {{ if not .Ordinal }}checked="checked"{{ end }} />
<label for="{{ $tab }}">
  {{- .Get 0 -}}
</label>
<div class="book-tabs-content markdown-inner">
  {{- .Inner -}}
</div>