PDF opens for me on macOS's Preview.app, Foxit PDF PhantomPDF on Windows and on Moon+ Reader on Android. Try to re-download archive.
Why only black-background version? It would be nice to have white-background PDF version or (even-better) white-background EPUB3 version. It's not that layout is too complex and EPUB3 means it 's possible to read on non-10" tablets and change fonts.
