title: bootstrap 4 create modal footer with multiple rows
body: <p>I'm attempting to get a modal footer in bootstrap 4 to have multiple 100% width rows.  So for the most basic bootstrap modal example below, is it possible to get the Close and Save changes buttons to be on different rows and both be 100% width?  </p>
  
  <pre><code>&lt;div class="modal fade" id="exampleModalLong" tabindex="-1" role="dialog" aria-labelledby="exampleModalLongTitle" aria-hidden="true"&gt;
        &lt;div class="modal-dialog" role="document"&gt;
          &lt;div class="modal-content"&gt;
            &lt;div class="modal-header"&gt;
                  &lt;h5 class="modal-title" id="exampleModalLongTitle"&gt;Modal title&lt;/h5&gt;
              &lt;button type="button" class="close" data-dismiss="modal" aria-label="Close"&gt;
                &lt;span aria-hidden="true"&gt;&amp;times;&lt;/span&gt;
              &lt;/button&gt;
            &lt;/div&gt;&lt;div class="modal-body"&gt;
              ...
            &lt;/div&gt;&lt;div class="modal-footer"&gt;
              &lt;button type="button" class="btn btn-secondary" data-dismiss="modal"&gt;Close&lt;/button&gt;
              &lt;button type="button" class="btn btn-primary"&gt;Save changes&lt;/button&gt;
            &lt;/div&gt;
          &lt;/div&gt;
        &lt;/div&gt;
      &lt;/div&gt;
  </code></pre>