<div class="row">
  <div class="col-xs-4 panel">
    <div class="panel-body">
      <h4>First Cell</h4>
    </div>
  </div>
  <div class="col-xs-4 panel">
    <div class="panel-body">
      <h4>Second Cell</h4>
    </div>
  </div>
  <div class="col-xs-4 panel">
    <div class="panel-body">
      <h4>Third Cell</h4>
    </div>
  </div>
</div>

<div class="row">
    <div class="col-xs-4">
        <div class=" panel">
            <div class="panel-body">
                 <h4>First Cell</h4>

            </div>
        </div>
    </div>
    <div class="col-xs-4">
        <div class=" panel">
            <div class="panel-body">
                 <h4>Second Cell</h4>

            </div>
        </div>
    </div>
    <div class="col-xs-4">
        <div class=" panel">
            <div class="panel-body">
                 <h4>Third Cell</h4>

            </div>
        </div>
    </div>
</div>

<div class="row">
    <div class="col-xs-4">
      <div class="panel">
          <div class="panel-body">
               <h4>First Cell</h4>

          </div>
      </div>
    </div>
    <div class="col-xs-4">
    <div class="panel">
        <div class="panel-body">
             <h4>Second Cell</h4>

        </div>
    </div>
    </div>
    <div class="col-xs-4">
    <div class="panel">
        <div class="panel-body">
             <h4>Third Cell</h4>

        </div>
    </div>
    </div>
</div>

<div class="row">
  <div class="col-md-6">
     <div class="col-md-12">
        <div class=" panel">
        <div class="panel-body">
             <h4>First Cell</h4>
        </div>
    </div>
     </div>
  </div>
  <div class="col-md-6">
     <div class="col-md-12">
        <div class=" panel">
        <div class="panel-body">
             <h4>Second Cell</h4>
        </div>
    </div>
     </div>
  </div>
</div>

.panel-4 {
  width:30%;
  margin-right:5%;
}