How to

All examples uses this template for the HTML code:

<!--Test -->
<div id="test">
    <div class="user">
        <img src="../img/avatar.png" alt="Esempio" class="img-thumbnail"><br>
        <a href="http://www.lombardoandrea.com" target="_blank" class="navbar-link">Andrea Lombardo</a>
    </div>

    <div class="list-group">

        <a href="#item-1" class="list-group-item" data-toggle="collapse">Item 1</a>

        <div class="list-group collapse" id="item-1">
            <a href="#" class="list-group-item">Item 1 di 1</a>
            <a href="#" class="list-group-item">Item 2 di 1</a>
            <a href="#item-1-1" class="list-group-item" data-toggle="collapse">Item 3 di 1</a>

            <div class="list-group collapse" id="item-1-1">
                <a href="#" class="list-group-item">Item 1 di 1.3</a>
                <a href="#" class="list-group-item">Item 2 di 1.3</a>
                <a href="#" class="list-group-item">Item 3 di 1.3</a>
            </div>

        </div>

        <a href="#item-2" class="list-group-item" data-toggle="collapse">Item 2</a>

        <div class="list-group collapse" id="item-2">
            <a href="#" class="list-group-item">Item 1 di 2</a>
            <a href="#" class="list-group-item">Item 2 di 2</a>
            <a href="#" class="list-group-item">Item 3 di 2</a>
        </div>

        <a href="#item-3" class="list-group-item" data-toggle="collapse">Item 3</a>

        <div class="list-group collapse" id="item-3">
            <a href="#" class="list-group-item">Item 1 di 3</a>
            <a href="#" class="list-group-item">Item 2 di 3</a>
            <a href="#item-3-1" class="list-group-item" data-toggle="collapse">Item 3 di 3</a>

            <div class="list-group collapse" id="item-3-1">
                <a href="#" class="list-group-item">Item 1 di 3.3</a>
                <a href="#" class="list-group-item">Item 2 di 3.3</a>
                <a href="#" class="list-group-item">Item 3 di 3.3</a>
            </div>

        </div>

        <a href="#item-4" class="list-group-item" data-toggle="collapse">Item 4</a>

        <div class="list-group collapse" id="item-4">
            <a href="#" class="list-group-item">Item 1 di 4</a>
            <a href="#" class="list-group-item">Item 2 di 4</a>
            <a href="#" class="list-group-item">Item 3 di 4</a>
        </div>

    </div>

</div>
<!--/Test -->

Watch the first example.