The Invert Preview option also doesn't work, so I'm stuck either toggling the theme as a whole or manually adding a stylesheet.
I think it would be nicest to have the iframe's background be white by default; that'd match paged export and how browsers render pages by default, while users can still overwrite it with a stylesheet just as before. If changing this by default is not desired, making it an option in the View menu or fixing Invert Preview could also work.
Alternatively text could be made white by default as in the editor, but that might lead to surprising results with the exported page looking different.
The Invert Preview option also doesn't work, so I'm stuck either toggling the theme as a whole or manually adding a stylesheet.
I think it would be nicest to have the iframe's background be white by default; that'd match paged export and how browsers render pages by default, while users can still overwrite it with a stylesheet just as before. If changing this by default is not desired, making it an option in the View menu or fixing Invert Preview could also work.
Alternatively text could be made white by default as in the editor, but that might lead to surprising results with the exported page looking different.