Metro UI CSS provides SideBar component. This component is great to create side menu.
For dropdown you must include metro-dropdown.js.
See code below for definition details.
<nav class="sidebar (light)">
<ul>
<li class="title">Items Group 1</li>
<li class="active"><a href="#"><i class="icon-home"></i>Dashboard</a></li>
<li class="stick bg-red"><a href="#"><i class="icon-cog"></i>Layouts</a></li>
<li class="stick bg-yellow">
<a class="dropdown-toggle" href="#"><i class="icon-tree-view"></i>Sub menu</a>
<ul class="dropdown-menu" data-role="dropdown">
<li><a href="">Subitem 1</a></li>
<li><a href="">Subitem 2</a></li>
<li><a href="">Subitem 3</a></li>
<li class="divider"></li>
<li><a href="">Subitem 4</a></li>
<li class="disabled"><a href="">Subitem 4</a></li>
</ul>
</li>
<li class="stick bg-green"><a href="#">Thread item</a></li>
<li class="disabled"><a href="#">Disabled item</a></li>
<li class="title">Items Group 2</li>
<li><a href="#">Other Item 1</a></li>
<li><a href="#">Other item 2</a></li>
<li><a href="#">Other item 3</a></li>
<li>
<a class="dropdown-toggle" href="#">Sub menu 2</a>
<ul class="dropdown-menu" data-role="dropdown">
<li><a href="">Subitem 1</a></li>
<li><a href="">Subitem 2</a></li>
<li><a href="">Subitem 3</a></li>
</ul>
</li>
</ul>
</nav>