I have opened the exploded ePub in Sigil - as, like Bernie suggested, I was thinking it may just be that the font sizes are specified in rem in the stylesheets and all the component html parts (of which there are lots)..
But (like Kovid said), Calibre is changing over the rem to em in conversion, and when I look at the stylesheet for a random part (part0003.html), all the rems are indeed ems...
So I am really puzzled why Google Play Books displays the text in teeny-tiny mode and doesn't allow me to change? Calibre converted tons of azw to ePub that display *fine* in GPB - so why just these handful that are weird? (and of course they're the handful that I really want to read!) lol
