Zurb Foundation css top menu does not work in drupal 8

I am having a problem creating a top menu in Drupal 8 using zurb foundation. I am currently using sass and gulp. when i open the foundation.css file, i cant find the css class="title-area", class="toggle-topbar menu-icon" and class="top-bar-section". I downloaded the whole complete package of zurb foundation framewaork. here is the code.

<nav class="top-bar" data-topbar role="navigation">
  <ul class="title-area">
    <li class="name">
      <h1><a href="#">My Site</a></h1>
    </li>
     <!-- Remove the class "menu-icon" to get rid of menu icon. Take out "Menu" to just have icon alone -->
    <li class="toggle-topbar menu-icon"><a href="#"><span>Menu</span></a></li>
  </ul>

  <section class="top-bar-section">
    <!-- Right Nav Section -->
    <ul class="right">
      <li class="active"><a href="#">Right Button Active</a></li>
      <li class="has-dropdown">
        <a href="#">Right Button Dropdown</a>
        <ul class="dropdown">
          <li><a href="#">First link in dropdown</a></li>
          <li class="active"><a href="#">Active link in dropdown</a></li>
        </ul>
      </li>
    </ul>

    <!-- Left Nav Section -->
    <ul class="left">
      <li><a href="#">Left Nav Button</a></li>
    </ul>
  </section>
</nav>

and this is how it displays