change popup background color to RGB 99FFCC

[architec]

change .App css in
https://github.com/arch-org/mistake/blob/main/src/pages/Popup/Popup.css

[architec]

@zestycoder you can do this one

[architec]

This issue is now open to anyone who is interested

[raulrusu88]

Hello, I'd like to take this.