title: how to use the CSS ::theme selector
body: <p>ive started making a HTML/CSS/Vanilla JS web component library, and so far everything is going great.
  im using the typical ::part and all that, but i stumbled accros ::theme selector aswell, which is supposed to give quick access to styling without a creator having to set up more than necesarry.</p>
  <p>problem is, i - whatever ive tried - can't seem to the get the ::theme selector work, is there anyone who can help me out ?</p>
  <p>screendump is from <a href="https://meowni.ca/posts/part-theme-explainer/" rel="nofollow noreferrer">https://meowni.ca/posts/part-theme-explainer/</a>, tried following but i dont know if this selector is still experimental ?, it would really make styling my components alot easier if it worked !</p>
  <p><a href="https://i.stack.imgur.com/oUSRX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oUSRX.png" alt="this screen is from following link that talks about it" /></a></p>