component.html

<link rel="import" href="https://www.polymer-project.org/1.0/components/polymer/polymer.html">
<dom-module id="component-1">
    <template>
      <style>
        :host {
          display: block;
        }
        .red-box {
          background-color: red;
          color: white;
          padding: 10px;
        }
      </style>
    </template>
    <script>
    (function() {
      'use strict';

      Polymer({
        is: 'component-1',

        properties: {
          foo: {
            type: String,
            value: 'component-1',
            notify: true
          }
        }
      });
    })();
    </script>
  </dom-module>