Nav

Add a container element with the nav class. And add child elements with the nav-item class. The nav-item with the active class will be highlighted.

<ul class="nav">
  <li class="nav-item">
    <a href="#">Elements</a>
  </li>
  <li class="nav-item active">
    <a href="#">Layout</a>
    <ul class="nav">
      <li class="nav-item">
        <a href="#">Flexbox grid</a>
      </li>
      <li class="nav-item">
        <a href="#">Responsive</a>
      </li>
      <li class="nav-item">
        <a href="#">Navbar</a>
      </li>
      <li class="nav-item">
        <a href="#">Empty states</a>
      </li>
    </ul>
  </li>
  <li class="nav-item">
    <a href="#">Components</a>
  </li>
  <li class="nav-item">
    <a href="#">Utilities</a>
  </li>
</ul>