can be used to give items
        an individual css style. For example, when an item has className
        'red', one can define a css style like:
      <pre class="prettyprint lang-css">
.vis-item.red {
  color: white;
  background-color: red;
  border-color: darkred;
}</pre>
        More details on how to style items can be found in the section
        <a href="#Styles">Styles</a>.
      </td>
    </tr>
    <tr>
      <td>align</td>
      <td>String</td>
      <td>no</td>
      <td>This field is optional.