<section class="filter">
  <nav>
    <div class="dropdown university">
      <div class="filter-heading">
        All Universities
      </div>
      <ul>
        <li>
          <a href="#">Harvard</a>
        </li>
        <li>
          <a href="#">MIT</a>
        </li>
      </ul>
    </div>

    <div class="dropdown subject">
      <div class="filter-heading">
        All Subjects
      </div>
      <ul>
        <li>
          <a href="#">Computer Science</a>
        </li>
        <li>
          <a href="#">History</a>
        </li>
      </ul>
    </div>

    <div class="dropdown featured">
      <div class="filter-heading">
        Newest
      </div>
      <ul>
        <li>
          <a href="#">Top Rated</a>
        </li>
        <li>
          <a href="#">Starting soonest</a>
        </li>
      </ul>
    </div>

    <form class="search">
      <input type="text" placeholder="Search for courses">
      <input type="submit">
    </form>
  </nav>
</section>
