<div class="tabbable tabs-left" style="margin-bottom: 18px;">
    <ul class="nav nav-tabs">
      <li class="active"><a href="#nested-tab1" data-toggle="tab">Section 1</a></li>
      <li><a href="#nested-tab2" data-toggle="tab">Section 2</a></li>
      <li><a href="#nested-tab3" data-toggle="tab">Section 3</a></li>
    </ul>
    <div class="tab-content" style="padding-bottom: 9px; border-bottom: 1px solid #ddd;">
      <div class="tab-pane active" id="nested-tab1">
        <p>I'm in Section 1.</p>

        <div class="tabbable" style="background: #f5f5f5; padding: 20px;">
          <ul class="nav nav-tabs">
            <li class="active"><a href="#nested-tab1-1" data-toggle="tab">1.1</a></li>
            <li><a href="#nested-tab1-2" data-toggle="tab">1.2</a></li>
            <li><a href="#nested-tab1-3" data-toggle="tab">1.3</a></li>
          </ul>
          <div class="tab-content" style="padding-bottom: 9px; border-bottom: 1px solid #ddd;">
            <div class="tab-pane active" id="nested-tab1-1">
              <p>I'm in Section 1.1.</p>
            </div>
            <div class="tab-pane" id="nested-tab1-2">
              <p>I'm in Section 1.2.</p>
            </div>
            <div class="tab-pane" id="nested-tab1-3">
              <p>I'm in Section 1.3.</p>
            </div>
          </div>
        </div>
      </div>
      <div class="tab-pane" id="nested-tab2">
        <p>Howdy, I'm in Section 2.</p>
      </div>
      <div class="tab-pane" id="nested-tab3">
        <p>What up girl, this is Section 3.</p>
      </div>
    </div>
  </div>