jrtechs-cs224w-notes/_includes/marginfigure.html

<label for="{{ include.id }}" class="margin-toggle">&#8853;</label>
<input type="checkbox" id="{{ include.id }}" class="margin-toggle">
<span class="marginnote">
    {%- assign prefix2 = include.url | slice: 0, 2 -%}
    {%- assign prefix7 = include.url | slice: 0, 7 -%}
    {%- assign prefix8 = include.url | slice: 0, 8 -%}
    {%- if prefix2 == '//' or prefix7 == 'http://' or prefix8 == 'https://' -%}
    <img class="fullwidth" src="{{ include.url }}" alt="{{ include.description }}" />
    {%- else -%}
    <img class="fullwidth" src="{{ site.baseurl }}/{{ include.url }}" alt="{{ include.description }}" />
    {%- endif -%}
    <br>
    {{ include.description }}
</span>