JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/js/bootstrap.min.js"></script>
<div id="MainMenu">
  <div class="list-group panel">
  	<a href="<?php echo base_url('shop/components') ?>" class="list-group-item strong">CATEGORY <i class="fa fa-home pull-right"></i></a>
  </div>
  <a href="#3D_Construction" class="list-group-item strong" data-toggle="collapse" data-parent="#MainMenu">3D Fablab Construction Part <i class="fa fa-caret-down"></i></a>
  <div class="collapse level_2" id="3D_Construction">
  	<a href="#SubMenu1" class="list-group-item strong" data-toggle="collapse" data-parent="#SubMenu1">20X20 RAILS <i class="fa fa-caret-down"></i></a>
	      <div class="collapse list-group-submenu" id="SubMenu1">
	      <a href="?rl=20x20_Rail&cti=1" class="list-group-item" data-parent="#SubMenu1">Screw</a>
	      </div>
  </div>
</div>

CSS

/* Latest compiled and minified CSS included as External Resource*/

/* Optional theme */
@import url('//netdna.bootstrapcdn.com/bootstrap/3.0.0/css/bootstrap-theme.min.css');

body {
    margin: 10px;
}