title: Can I use non existing CSS classes?
body: <p>I have a table where I show/hide a full column by jQuery via a CSS class that doesn't exist:</p>
  
  <pre><code>&lt;table&gt;
     &lt;thead&gt;
        &lt;tr&gt;
           &lt;th&gt;&lt;/th&gt;
           &lt;th class="target"&gt;&lt;/th&gt;
           &lt;th&gt;&lt;/th&gt;
        &lt;/tr&gt;
     &lt;/thead&gt;
     &lt;tbody&gt;
        &lt;tr&gt;
           &lt;td&gt;&lt;/td&gt;
           &lt;td class="target"&gt;&lt;/td&gt;
           &lt;td&gt;&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
           &lt;td&gt;&lt;/td&gt;
           &lt;td class="target"&gt;&lt;/td&gt;
           &lt;td&gt;&lt;/td&gt;
        &lt;/tr&gt;
     &lt;/tbody&gt;
  &lt;/table&gt;
  </code></pre>
  
  <p>With this DOM I can do this in one line via jQuery: <code>$('.target').css('display','none');</code></p>
  
  <p>This works perfectly, but is it valid to use CSS classes that aren't defined? Should I create an empty class for it?</p>
  
  <pre><code>&lt;style&gt;.target{}&lt;/style&gt;
  </code></pre>
  
  <p>Are there any side effects or is there a better way to do this?</p>