In case anyone else has trouble with the "Save as PDF" part, I did it successfully using Firefox on OSX: from the print menu, choose "show details" and change all headers/footers to "--blank--" so there's no ugly URLs/dates in the corners, then press PDF -> "Save as PDF". (In Chrome, on the other hand, saving/printing as PDF chopped each page into quarters for me...) At least in the one chapter I've saved so far, all the math notation renders just like in the HTML version.