title: How to add custom style to paper-icon-button
body: <p>I have the following code:</p>
  
  <pre><code>&lt;template is="dom-repeat" items="{{todos}}" sort="sortComparator"&gt;
                  &lt;div class="row"&gt;
                          &lt;paper-icon-button icon="arrow-forward"&gt;&lt;/paper-icon-button&gt;
                      &lt;span&gt;{{item.name}}&lt;/span&gt;
                      &lt;span class="btn-set"&gt;
                          &lt;paper-icon-button icon="delete" on-tap="deleteTodo"&gt;delete&lt;/paper-icon-button&gt;
                          &lt;paper-icon-button icon="star" on-tap="toggleFavorite"&gt;star&lt;/paper-icon-button&gt;
                      &lt;span&gt;
                  &lt;/div&gt;                              
              &lt;/template&gt;  
  </code></pre>
  
  <p>I want to add a color yellow to <code>icon="star"</code> if <code>item.isFav</code> is true. But i am not able to find a way to do it. Any suggestion, how to do it.</p>