Originally Posted by JSWolf
I can understand indents shifting. But why would you want the margins shifting? In fact, just do away with the margins and you'll have a better reading experience (IMHO).
I think a small amount of margin is needed for a couple of reasons.
1) On some readers, the surface of the screen may be slightly lower than the surface of the outer casing, so you will get shadowing on the edges of the screen, so a couple of millimetres of margin at least would be nice.
2) Adobe's ePub renderer on Sony devices prints page numbers in the right hand margin so you need to add some extra space to avoid overlapping them.