I'm guessing it's the page_styles.css file:
Code:
@page {
margin-bottom: 5pt;
margin-left: 72pt;
margin-right: 72pt;
margin-top: 5pt;
size: 612pt 792pt
}
I opened the epub in sigil and deleted those lines from that file and then it was ok.
For Past Masters Thirty Five I pulled it into calibre and then ran the Modify ePub plugin and had the box "Modify @page and body margin styles" checked and that fixed it. I'm not sure but I think this plugin also looks at your calibre conversion settings for that and if so, mine says in the Convert box under Page setup, margins are set to 0.0pt for all 4, and I've selected Default profile for input profile and Tablet for Output profile.
So using the Modify ePub plugin is probably the least work.
Could you also send a message to pulpmeister letting him know about the problem?
Edit: Hah, doitsu beat me to it.