Hurrah, I got it, Diane, thank you! :)
I can see what you mean. The screenshot makes me think your husband's Firefox browser is using special settings to override the site's colors.
In Firefox, if you go to Options (may also be Preferences) -> Content -> Colors, there is a checkbox that says, "Allow pages to choose their own colors, instead of my selections above".
If that option is unchecked, your site will appear as it does in the screenshot you sent. You can read more about this in the support documentation for Firefox here:
I believe that's what is happening here -- can you check your husband's Firefox settings to confirm?