Include the Help folder in both versions of the program (iOS and macOS).
In Xcode, be sure to include it as a "folder reference" rather than as a "group".

On each platform, include only one Platform Style.  Name it PlatformStyle.css,
and include it as a sibling of the Help folder, not a child.
For iOS, use the mobile version of PlatformStyle.css.
For macOS, use the desktop version of PlatformStyle.css.
