theme-mnemosyne-hugo/layouts/shortcodes/admonition.html

<div class="panel{{ with .Get 1 }} is-{{.}}{{ end }}">
    <p class="panel-heading">
        {{ .Get 0 | title }}
    </p>
    <div class="panel-block">
        <div class="content">
            {{ .Inner | $.Page.RenderString }}
        </div>
    </div>
</div>