Accordion menu Dropdown

  Accordion Menu will automatically open and highlight the sub-menu item that contains the current page link when the page is opened

From Bootstrap:



Html:
<div id="MainMenu">
  <div class="list-group panel">
    <a href="#demo3" class="list-group-item list-group-item-success" data-toggle="collapse" data-parent="#MainMenu">Item 3</a>
    <div class="collapse" id="demo3">
      <a href="#SubMenu1" class="list-group-item" data-toggle="collapse" data-parent="#SubMenu1">Subitem 1 <i class="fa fa-caret-down"></i></a>
      <div class="collapse list-group-submenu" id="SubMenu1">
        <a href="#" class="list-group-item" data-parent="#SubMenu1">Subitem 1 a</a>
        <a href="#" class="list-group-item" data-parent="#SubMenu1">Subitem 2 b</a>
        <a href="#SubSubMenu1" class="list-group-item" data-toggle="collapse" data-parent="#SubSubMenu1">Subitem 3 c <i class="fa fa-caret-down"></i></a>
        <div class="collapse list-group-submenu list-group-submenu-1" id="SubSubMenu1">
          <a href="#" class="list-group-item" data-parent="#SubSubMenu1">Sub sub item 1</a>
          <a href="#" class="list-group-item" data-parent="#SubSubMenu1">Sub sub item 2</a>
        </div>
        <a href="#" class="list-group-item" data-parent="#SubMenu1">Subitem 4 d</a>
      </div>
      <a href="javascript:;" class="list-group-item">Subitem 2</a>
      <a href="javascript:;" class="list-group-item">Subitem 3</a>
    </div>
    <a href="#demo4" class="list-group-item list-group-item-success" data-toggle="collapse" data-parent="#MainMenu">Item 4</a>
    <div class="collapse" id="demo4">
      <a href="" class="list-group-item">Subitem 1</a>
      <a href="" class="list-group-item">Subitem 2</a>
      <a href="" class="list-group-item">Subitem 3</a>
    </div>
  </div>
</div>