 But <code class="astro-3HS6YOU4">.main-content</code> is
                      <u class="astro-3HS6YOU4">required</u> and should be used
                      <u class="astro-3HS6YOU4">single</u>.
                    </p>
                    <p class="astro-3HS6YOU4">
                      <code class="astro-3HS6YOU4">.app-main</code> element is based on
                      <a href="http://getbootstrap.com/examples/sticky-footer/" target="_blank" class="astro-3HS6YOU4">sticky footer</a>.
                