gcg-website/layouts/shortcodes/collapsible.html

<div class="container mb-0">
  <div class="card border-primary rounded-0 hover-shadow mb-5">
    <div class="card-body mb-0">
      <details class="mb-0">
      <summary class="mb-0">{{ .Get "title" }}</summary>
      <div class="content"><p class="content">{{ .Inner }}</p></div>
      </details>
    </div>
  </div>
</div>