Dark site

Hi, when I insert a site page with a white background in my note, is it possible to turn it in a dark theme, please ?

How are you doing this insertion?

I guess he means a PDF, I use the LaTeXWorkshop Extension for VS Code a lot and it has a feature to basically invert (its a bit more advanced because most images look just a bit altered) the PDF in Preview.

I think that would actually be really cool in Obsidian too!

When I use this :

<iframe 
src="https://embed.blablabla="940"
 height="560" frameborder="0"></iframe>
const iframes = document.querySelectorAll('iframe');

function toggleTheme() {
  for (i = 0; i < iframes.length; i++) {
    iframes[i].classList.toggle('is-dark');
  }
}
.is-dark {
  filter: invert(80%);
}
<!doctype html>
<html lang="en">

<body>

  <button onClick="toggleTheme();">Toogle Theme</button>

  <iframe id="the-iframe" src="https://wikipedia.org/"></iframe>

</body>

</html>

can these be implemented inside obsidian ?
got it from stack over flow and here is the link and see it in action javascript - How to change background color of an iframe while toggling light/dark mode? - Stack Overflow