Different issues when copy-pasting code in different browsers

[sobolevn]

Thanks a lot for fixing #91

It now works!

But, now I face different issues. In FireFox + Keynote on macos 14.5 I get this result when pasting code from the app:

The app says:

For best results, copy from Safari with Keynote decks and from Chrome with Google Slides decks.

Ok, let's try Safari :)

Here's how it looks both in the app and in Keynote.

What's wrong:

• On Firefox encoding seems off (?)
• On Safari token highlight seems off