Make popups scrollable internally instead of adding scrollbar to body

[lorumic]

• Changed some CSS so that popups with an overflowing content can be scrollable internally, instead of adding a scrollbar to the body, so that the layout of the page is kept and does not seem broken.
• Browser compatibility is not altered by the changes in this PR.

Before:

After:

[Zarel]

I don't particularly like internal scrollbars for popups. I guess the current system is a little ugly, but I'm happy with how convenient/usable it is.

(It was also necessary on mobile back when internal scrolling was unnecessarily difficult on mobile.)

I guess one compromise would be to put it in an overlay and have the overlay be scrollable. You'd have to darken the overlay but that might not be a bad idea for Options.

[lorumic]

I guess one compromise would be to put it in an overlay and have the overlay be scrollable. You'd have to darken the overlay but that might not be a bad idea for Options.

Thanks for the feedback @Zarel. Just to check that I understood correctly, you mean using, for this popup, the same approach that is used for the avatar selection, right?