[Perkin]

Right, I think I know what's happened, those @font-face definition are trying to access the EMBEDED fonts which don't exist, what you need to do is either remove the whole of the following lines (so it will use the fonts already on system)

@font-face {
font-family: "Baskerville";
font-style: normal;
font-weight: normal;
src:local(Baskerville);
}
@font-face {
font-family: "Rockwell";
font-style: normal;
font-weight: normal;
src:local(Rockwell);
}

OR to embed the fonts, right click on the Fonts folder in book browser window, and 'Add Existing Items...' , then navigate to your fonts folder and select the Baskerville font, then again for Rockwell font.

As long as the epub will be for your own private use, it should be alright, I'm not sure about copyright on those fonts.

You may need to change the

src:local(Baskerville)

change it to

src:url(../Fonts/Baskerville.ttf) format(opentype);;

and do the Rockwell definition to read

src:url(../Fonts/Rockwell.ttf) format(opentype);;

You should then be good