title: Changing the background color of the title block of an extended twig template
body: <p>I have a twig template used for Bootstrap popovers. The code is:</p>
  
  <pre><code>span class="popover-wrapper {% block wrapper_class %}{% endblock %}"&gt;
    &lt;button
        type="button"
        class="btn-link popover-link {% block link_class %}{% endblock %}"
        tabindex="0"
        role="button"
        data-toggle="popover"
        data-placement="bottom"
        data-title="{% block title %}{% endblock %}"
        &gt;{% block link_text %}{% endblock %}&lt;/button&gt;
    &lt;div class="popover-inner-content {% block content_class %}{% endblock %}"&gt;
      {% block content %}{% endblock %}
    &lt;/div&gt;
  &lt;/span&gt;
  </code></pre>
  
  <p>when extending this template into another <code>html.twig</code> view,</p>
  
  <pre><code>{% embed 'fragments/popover.html.twig' %}
      {% block link_class %}more-sections{% endblock %}
      {% block link_text %}
           &lt;span class="fa fa-info-circle"&gt;&lt;/span&gt;
  
      {% endblock %}
      {% block title %}&lt;div&gt;Contact Info&lt;/div&gt;{% endblock %}
      {% block content %} .......
  </code></pre>
  
  <p>When adding <code>style="background-color: blue;"</code> to the title div, it disables the popover appear/disappear functionality. How can I alter the backgrond color of the popover Title section></p>