[Groff] Unwanted margins in gpresent pdf

[Tom Wolfe]

Hello,

I'm new to groff. I worked as a typesetter back in the late 70s and
groff seems a more natural way to create documents than MS or LaTeX.
I'm a college teacher, so naturally one of the first things I want to
do is replace Powerpoint. I've been experimenting with gpresent. It
seems like an ideal answer. However, after processing the demo my pdf
file  has white margins around the page. It is especiallly noticeable
aoround the pages with color backgrounds and the sidebar format. I've
spent what I feel is a reasonable amount of time with many man and
info pages but can't solve this problem. Anyone willing to help? I''m
using Mac OS X, 10.4.8.

Tom