bottom margin causes too much whitespace

Another issue, that I think is relatively minor—the bottom margin of 28px that's the default for most of the grid classes causes a lot of extra white space between the header and the main content container. In practice, I've ended up actually changing the grid in the Square Grid files to get rid of this space.

I don't know if this is something that can/should be fixed, but it's caused problems on both of my sites that use this theme.

NOTE: ACK! I realized that the title of this is vague, but I can't figure out how to fix it.