Hallo,
thank you for your grid-theme!

But I think your width (in %) in your css-files are wrong. For example, when I create two blocks, a "span-2" and a "span-9" in a "12-container", the blocks won't be display side by side. I think the mistale is in the "left:2%" and "margin-right:2%" of each span. So the two spans will be greater than 100% and so they could not be displayed side by side.

Perhaps the mistake could be fixed for other users, who want to use the grid-system.

Best regardsa from Germany
the-sandman