Allowing use of grid classes inside regions

As brought up in places like http://drupal.org/node/1245428, it has been difficult to add columns using the same grid system INSIDE of Omega theme regions (using Panels, Display Suite, etc.), since the regions already have grid-x classes themselves, and hence are already 20px narrower than their containers, leaving not enough space for the desired number of columns within them.

I came up with a solution that's fairly easy to use (and pretty generic), but it could be made more elegant if integrated straight into Omega. Here's what I did:

I created a grid-overrides.css file in my sub-theme.

Then I put in overrides like this:

.container-12 .grid-1.no-gutter {
margin: 0;
width: 80px;
}

Then I can add "no-gutter" to the "Additional region classes" in the Omega settings for a region. Then that particular region will be the full width for its number of columns, without the usual 10px gutter on each side. What that means is I can put grid-based columns INSIDE that region (by defining a wrapper around any field and applying a regular "grid-x" class to it, which is easy with Display Suite) and have them fit, as if the region were just a container, not a grid column itself.

I also added this definition:

.add-gutter {
margin: 0 10px;
}

...which I do need to remember to add to any full-width fields within a no-gutter region, but that's not too hard.