title: Polymer's paper-styles doesn't work
body: <p>I tried to create my own component using Polymer's material design elements. But, I can't figure out how to use <code>paper-styles</code>.</p>
  
  <p>Here is my component code(bb-book.html)</p>
  
  <pre><code>&lt;link rel="import" href="bower_components/polymer/polymer.html"&gt;
  &lt;link rel="import" href="bower_components/paper-header-panel/paper-header-panel.html"&gt;
  &lt;link rel="import" href="bower_components/paper-toolbar/paper-toolbar.html"&gt;
  &lt;link rel="import" href="bower_components/paper-styles/paper-styles.html"&gt;
  
  &lt;dom-module id="bb-book"&gt;
    &lt;style&gt;
    .book {
      float: left;
      width: 160px;
      height: 240px;
      margin: 12px;
      @apply(--shadow-elevation-2dp);
    }
    &lt;/style&gt;
    &lt;template&gt;
      &lt;paper-header-panel class="book"&gt;
        &lt;paper-toolbar&gt;&lt;div&gt;Hello World!&lt;/div&gt;&lt;/paper-toolbar&gt;
        &lt;p&gt;Hello World&lt;/p&gt;
      &lt;/paper-header-panel&gt;
    &lt;/template&gt;
  
    &lt;script&gt;
      Polymer({
        is: 'bb-book',
        properties: {
          book_id: Number
        }
      });
    &lt;/script&gt;
  &lt;/dom-module&gt;
  </code></pre>
  
  <p>Here is the index.html using my component(<code>bb-book</code>)</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
    &lt;head&gt;
      &lt;!-- 1. Load webcomponents-lite.min.js for polyfill support. --&gt;
      &lt;script src="bower_components/webcomponentsjs/webcomponents-lite.min.js"&gt;
      &lt;/script&gt;
  
      &lt;!-- 2. Use an HTML Import to bring in some elements. --&gt;
      &lt;link rel="import" href="bb-book.html"&gt;
    &lt;/head&gt;
    &lt;body&gt;
      &lt;!-- 3. Declare the element. Configure using its attributes. --&gt;
      &lt;bb-book&gt;&lt;/bb-book&gt;
      &lt;bb-book&gt;&lt;/bb-book&gt;
      &lt;bb-book&gt;&lt;/bb-book&gt;
      &lt;bb-book&gt;&lt;/bb-book&gt;
    &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>It shows my component. But, the font is not a material design font I expected.
  See the below image. Am I missing something?</p>
  
  <p><a href="http://s24.postimg.org/q94s9bl7p/Screen_Shot_2015_07_01_at_00_07_31.png" rel="nofollow">http://s24.postimg.org/q94s9bl7p/Screen_Shot_2015_07_01_at_00_07_31.png</a></p>