<code class="html">
      <div class="u-color-background-gray-100 transparent-test-block">
        <code>u-color-background-gray-100</code>
      </div>

      <div class="u-color-background-gray-300 transparent-test-block">
        <code>u-color-background-gray-300</code>
      </div>
</code>

<code class="html">
      [100, 300].each('<div class="u-color-background-gray-{value} transparent-test-block">
        <code>u-color-background-gray-{value}</code>
      </div>');
</code>