title: Knockout css binding
body: <p>I have a button that I want to toggle the class when clicked.</p>
  
  <p>This is what I currently have. </p>
  
  <pre><code> &lt;table&gt;
       &lt;tbody data-bind="foreach: item "&gt;
        &lt;tr&gt;
           &lt;td&gt;&lt;a data-bind="click:    $parent.selectItem,    text:   Name, css: { 'whitishBtn button_small': selected(), 'greenishBtn button_small': !selected() }"&gt;&lt;/a&gt;&lt;/td&gt;
         &lt;/tr&gt;
       &lt;/tbody&gt;
       &lt;/table&gt;
  </code></pre>
  
  <p>it almost works. When green it works as expected but only has whitishBtn class when white.</p>