pc-scoped.html

<!-- 
  You can define styles at the top of the document, and they will
  be applied to all elements within this file.
-->
<style>
  div {
    color: red;
  }
</style>

<div>
  I'm red!

  <span>
    
    <!-- 
      You can also define styles within an element, 
      and they will only be applied to that element, 
      along with all of its descendents. 
    -->
    <style>
      color: purple;
    </style>
    I'm purple!
  </span>
</div>