Older and applied font mixes up

[AnkurMal]

The font messes up with the old font of github while selecting a text.

[AmraniCh]

Hey, thanks for opening this issue.

Can provide extra details about this issue ? what extension options you use ? if the file code in the screenshot is in public repository, can you send me the URL of that file please ?

I tested the same thing with dark mode enabled and the issue not happens with me! that weird!

[AnkurMal]

Font: JetBrains Mono
Weight: 400
Size: Not set to anything
Hide indentation guides is turned off
Browser is Chrome, OS is windows 11

The link to my code.
(Although happens with any code)

Also, not using any extra extension for dark mode, its just Github's dark mode

[JiaChen-Zeng]

On my browser it's not mixed up but the selected text offsets a little bit