w as part of a Polymer element -->
    <polymer-element name="x-card" attributes="z">
      <template>
        <style>
          :host {
            display: block;
          }
        </style>
        <paper-shadow target="{{}}" z="{{z}}"></paper-shadow>
      </template>
      <script>
        Polymer('x-card', {
          publish: {
            z: {value: 1, reflect: true}
          }
        });
      </script>
    </polymer-element>
    <div>
      <x-card class="card" z="2"></x-card>
    </div>
    <a