polymer/test/unit/styling-remote-module-sheet.html

<link rel="import" href="sub/style-import.html">
<dom-module id="remote-styles">
<template>
  <style include="style-import"></style>
  <style>
    #simple {
      border: 3px solid orange;
    }

    .scoped, [selected] {
      border: 4px solid pink;
    }

    #zazz {
      border: 6px solid tomato;
    }
  </style>
</template>
</dom-module>