{{ $marginnoteDomIdSuffix := .Ordinal }}
<label
  for="marginnote-{{.Page.File.UniqueID}}-{{ $marginnoteDomIdSuffix }}"
  class="margin-toggle"
  >&#8853;
</label>
<input
  type="checkbox"
  id="marginnote-{{.Page.File.UniqueID}}-{{ $marginnoteDomIdSuffix }}"
  class="margin-toggle"
/>
<span class="marginnote">{{ .Inner | markdownify}}</span>