Modified version of https://github.com/Polymer/polymer-tutorial/blob/master/finished/post-card.html to answer http://stackoverflow.com/questions/24530619/automatic-node-finding-not-working

post-card.html

<link rel="import" href="../components/polymer/polymer.html">
<link rel="import" href="../components/core-icon-button/core-icon-button.html">

<polymer-element name="post-card">
  <template>
    <style>
    :host {
      display: block;
      position: relative;
      background-color: white;
      padding: 20px;
      width: 100%;
      font-size: 1.2rem;
      font-weight: 300;
    }
    .card-header {
      margin-bottom: 10px;
    }
    polyfill-next-selector { content: '.card-header h2'; }
    .card-header ::content h2 {
      margin: 0;
      font-size: 1.8rem;
      font-weight: 300;
    }
    polyfill-next-selector { content: '.card-header img'; }
    .card-header ::content img {
      width: 70px;
      border-radius: 50%;
      margin: 10px;
    }
    core-icon-button {
      position: absolute;
      top: 3px;
      right: 3px;
      fill: #636363;
    }
    :host([favorite]) core-icon-button {
      fill: #da4336;
    }
    </style>
    <div class="card-header" layout horizontal center>
      <content select="img"></content>
      <content select="h2"></content>
    </div>
    <core-icon-button
      id="favicon"
      icon="favorite"
      on-tap="{{favoriteTapped}}">
    </core-icon-button>
    <p>Love count: {{loveCount}}</p>
    <content></content>
  </template>
  <script>
  Polymer('post-card', {
    loveCount: 0,
    publish: {
      favorite: {
        value: false,
        reflect: true
      }
    },
    favoriteTapped: function(event, detail, sender) {
      this.loveCount++;
      this.favorite = !this.favorite;
      this.fire('favorite-tap');
    }
  });
  </script>
</polymer-element>