Bootstrap Accordion in Accordion

SO http://stackoverflow.com/q/12086548/570918

HTML

<script src="//netdna.bootstrapcdn.com/twitter-bootstrap/2.1.0/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="//netdna.bootstrapcdn.com/twitter-bootstrap/2.1.0/css/bootstrap.min.css">
<div class="accordion" id="accordion1">
                <!-- Element Group Heading -->
                <div class="accordion-heading">
                    <a class="accordion-toggle" data-toggle="collapse" data-parent="#accordion1" href="#collapse1"> 
                    <b>Element Group 1</b>
                    </a>
                </div>
                <!-- Elements -->
                <div id="collapse1" class="accordion-body collapse">
                   <!--  -->
                        <div class="accordion" id="accordion1-1">
                            <div class="accordion-heading" style="margin-left: 30px">
                                <label class="radio" class="accordion-toggle" data-toggle="collapse"    data-parent="#accordion1-1" data-target="#collapseOne1-1">
                             Element One
                                </label>
                            </div>
                            <div id="collapseOne1-1" class="accordion-body collapse">
                            <div class="accordion-inner" style="margin-left: 60px">

                            <!-- Sample Description -->
                            <<br/>
                            </div></div>
                        </div>
                        <!--  -->
                        <div class="accordion" id="accordion1-2">
                            <div class="accordion-heading" style="margin-left: 30px">
                                <label class="radio" class="accordion-toggle" data-toggle="collapse"    data-parent="#accordion1-2" data-target="#collapseOne1-2">
                                <input type="radio" name="optionsCheckboxList" value="2"/>Element Two
                                </label>
                            </div>
                            <div...