Website/layouts/shortcodes/iframe.html

{{ $src := .Get "src" -}}
{{ $class := .Get "class" -}}

<div class="wrap-element{{ with $class }} {{ . }}{{ end }}">
  <iframe class="wrapped-iframe"
    {{ with $src }}src="{{ . }}"{{ end }}
    frameborder="0" allowfullscreen>
  </iframe>
</div>