preso/themes/reveal-hugo/layouts/partials/reveal-hugo/slides.html

<!-- Use the array of pages passed as a param -->
{{ range . -}}
<!-- Don't process empty content files -->
  {{- if ne (len .Content) 0 -}}
    <!-- Remove the <hr /> tag generated by blackfriday for footnotes -->
    {{- $content := replace .Content "<div class=\"footnotes\">\n\n<hr />" "<div class=\"footnotes\">" -}}
    <!-- <code> blocks processed by Hugo's highlighter have a data-lang attribute. For those, we disable -->
    <!-- highlight.js by changing the language class to "nohighlight", and adding "data-noescape".       -->
    {{- $content := replaceRE `<code class="language-\w+"\s+data-lang="\w+"` `<code class="nohighlight" data-noescape` $content -}}    
    <!-- enable Highlight.js line numbers when the markdown code block language selection is followed by "{}" e.g. ```js{} -->
    {{- $content := replaceRE `(<code class="language-\w+){}(">)` `$1" data-line-numbers>` $content -}}
    <!-- enable Highlight.js line highlights when the language selection is followed by "{<line numbers>}" e.g. ```js{1,5-7} -->          
    {{- $content := replaceRE `(<code class="language-\w+){(\S+)}(">)` `$1" data-line-numbers="$2">` $content -}}            
    <!-- Support both <hr /> (blackfriday) and <hr> (mmark) -->
    {{- $content := replace $content "<hr>" "<hr />" -}}
    <!-- Split the processed content by <hr /> tag -->
    {{- range (split $content "<hr />") -}}
      <!-- Only wrap in <section> tag if not already wrapped by shortcode -->
      {{- if not (in . "data-noprocess") -}}
<section>
          {{- end -}}
  {{- . | safeHTML -}}
</section>
    {{- end -}}
  {{- end -}}
{{- end }}