Subnav
This is how you lay out dropdown menus to appear below their parent link in main navigations.
<ul class="navbar__menu">
<li>
<a href="/">Navigation item</a>
<ul class="subnav">
<li>
<a href="/" class="subnav-item">sublink.title</a>
</li>
</ul>
</li>
</ul>