title: Can't find style in html but can find in styleSheets
body: <p>When i using Material-ui Box component(such as <code>&lt;Box padding={2}/&gt;</code>), I can't find style in html, but I can find style in document.styleSheets, why ?</p>
  <p><a href="https://i.stack.imgur.com/REJvA.png" rel="nofollow noreferrer">screenshot of index.html</a></p>
  <p><a href="https://i.stack.imgur.com/tatCE.png" rel="nofollow noreferrer">screenshot of document.styleSheets</a></p>