[Feature Request] Custom themes

[boredboardboared]

I'd like support for custom themes. As someone familiar with CSS, even a barebones stylesheet reader would do.

[Jinjinov]

Custom themes would be very easy if the code was only for Windows, Linux, Android, iOS, macOS - simply add a css folder and include any custom css files from that folder.

But the code also works on web and that wouldn't work there.

One option would be to use css differently on web than on other platforms, but I really don't like to have special cases per platform because every special case makes code maintenance more complicated.

I will try to think of a solution. Do you have any suggestions?