Use class .Tabs to create a structure of tabs inline.
Use class .Tabs-item in descendent tag <a>.
Use class .is-active for active tab.
<!-- Tabs -->
<ul class="Tabs">
<li><a class="Tabs-item is-active" href="#">Tab 1</a></li>
<li><a href="#" class="Tabs-item">Tab 2</a></li>
</ul>