navigation-menu.html

<nav class="header_nav">
  <ul>
    <li class="nav_item">
      <span class="item_name">item</span>
      <ul class="item_dropdawn">
        <li class="dropdawn_item"><a href="#">item dropdawn</a></li>
      </ul>
    </li>
  </ul>
</nav>
<div id="humburger-icon">
  <span></span>
  <span></span>
  <span></span>
  <span></span>
</div>