{{ $caption := .Get "caption" }}
<figure role="group" aria-describedby="caption-{{ $caption | base64Encode | truncate 20 "" }}">
  {{ .Inner }}
  <figcaption id="caption-{{ $caption | base64Encode | truncate 20 "" }}">
    {{ .Get "caption" | safeHTML }}
  </figcaption>
</figure>