One of the key differences between Blueprint and 960, aside from nomenclature, is the way the grid columns receive their gutters. In Blueprint, all the gutters are 10px wide (a bit too narrow for my taste), and are to the right side. The last column in each row needs class="last" to remove the margin. This means that neither the left nor right sides of a container have any spacing. For the most part, this is no big deal, but if a user’s browser is constrained, body text actually touches the browser chrome. In the 960 Grid System, each column has 10px margin on both the left and right sides. This allows for the overall container to have a 10px buffer at the edges, and the margins combine between columns to form 20px gutters (a bit more room to breathe). Additionally, there is no need to add an extra class for the last column in a row. In some unique cases, you might want grid units nested within a parent grid unit. In this case, you will need class="alpha" and class="omega" on the first/last child in each row. It’s a bit more work, but is more of a fringe situation, so it won’t come up as often.