When the about modal is being displayed, it is appended to the end of the document's body and there's no way to wrap it around something that would allow us custom styling in some cases.
It would be nice to have a way to set the background image through props, or dynamically set a custom CSS class on at least the top-level element.
For now the only way to go around this is to set a CSS class on the document's body and it seems like a very ugly hack for me.