You know, I'm not sure why I did that now but it doesn't look crowded at all. The left and right .1em actually gives it a tad more space. The -.1em is for the top and bottom. I think it wasn't lining up right without it. But I have a later book that doesn't have that and it looks fine so I'm not recommending it. I believe I got it that code from a post on the mobi mobileread forum. I found something better later.
Anyway, I was really just showing how the media query is done.