Where is an exact location of "userstyles.css" in debugger?

[tessus]

User CSS is not supported for HTML notes in Joplin - only for markdown notes.

see:

Custom CSS doesn't apply to rendered HTML, only rendered Markdown

Even though I actually worked on the custom CSS feature, I’m bashful to say that I can’t quite figure out why the userstyle.css file is only being applied on the rendered Markdown notes and not on the rendered HTML ones. I tried following the logic yesterday but got fairly stuck, since there’s lots of layers of indirection.