title: What does font-size: 100% on the html element do?
body: <p>I am in the process to start a new project. I am asking myself: Why should I add <code>font-size: 100%</code> on the <code>html</code> element when I am using the <code>em</code> unit anyway?  </p>
  
  <p>What does this <code>100%</code> to - 100% compared to what?</p>