<div class=“left-sidebar hidden-when-sm-width”>

{% assign sorted_api_book = api_book | sort %}
{% for api_group in sorted_api_book %}
{% assign api_group_name = api_group[0] | downcase %}
<a class="left-sidebar-item {% if api_group_name == filename %}active{% endif %}" href="{{ site.baseurl }}/{{ api_group_name }}">{{ api_group_name | capitalize }}</a>
{% endfor %}

</div>