Bootstrap and Tables

HTML

<link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css">
<div class="container">
  <div class="row">
    <div class="col-xs-6 col-sm-4 col-md-3">
      <table class="red">
        <tr>
          <td rowspan="2">a</td>
          <td>1</td>
          <td>2</td>
        </tr>
        <tr>
          <td>3</td>
          <td>4</td>
        </tr>
        <tr>
          <td>5</td>
          <td>6</td>
        </tr>
      </table>
    </div>
  </div>
</div>

CSS

.red {
  background-color: red;
}

.blue {
  background-color: blue;
}

.green {
  background-color: green;
}

table {
    width: 100%;
    margin-bottom: 30px;
}

th, td {
    text-align: center;
    padding: 5px 0;
    color: white;
}