tag_list.html

<section class="panel panel-default">
    <div class="panel-heading">
        <h3 class="panel-title"><span class="glyphicon glyphicon-tags"></span>&nbsp;&nbsp;Tags</h3>
    </div>
    <div style="padding: 5px;">
    <ul class="nav nav-pills">
        {% for category in site.tags %}
        {% capture tag_url %}{{ site.tag_dir }}/{{ category | first | slugize | downcase | replace:' ','-' | append:'/index.html'}}{% endcapture %}
        <li {% if tag_url == page.url %}class='active'{% endif %}>
        {% capture tag-size %}{{ category | last | size }}{% endcapture %}
        <a class="{% if tag-size > 20 %}tags-20{% elsif  tag-size > 15 %}tags-15{% elsif tag-size > 10 %}tags-10{% elsif tag-size > 5 %}tags-5{% else %}tags-1{% endif %}"
                href="{{ root_url | append:'/' | append:tag_url }}">
            <span class="badge pull-right">{{ category | last | size }}</span>
            {{ category | first }}
        </a>
        </li>
        {% endfor %}

    </ul>
    </div>
</section>