<link rel="import"
      href="/components/polymer/polymer.html">

<polymer-element name="proto-element">
  <template>
    <span>I'm <b>proto-element</b>. Check out my prototype.</span>
  </template>
  <script>
    Polymer('proto-element', {
      ready: function() {
        //...
      }
    });
  </script>
</polymer-element>