{{- $src := .Get "src" }}
{{- $sub := .Get "sub" -}}
{{- $alt := .Get "alt" -}}
<div class="thumbnail-container">
<a href="{{ $src }}"><div class="thumbnail">
  <center><img src="{{ $src }}" alt="{{ $alt }}" title="{{ $alt }}"></center>
  {{- if $sub -}}
  <sub>{{ $sub }}</sub>
  {{- end -}}
</div></a>
</div>