title: How to add Bootstrap bg-x (e.g., bg-danger) classes to input textboxes?
body: <p>The background color associated with Bootstrap's <code>bg-danger</code> class is not being applied to an input textbox of class <code>form-control</code>. How can this be done?</p>
  
  <pre><code>&lt;div class="form"&gt;
      &lt;div class="form-group has-error"&gt;
          &lt;input type="text" class="form-control bg-danger"&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>