If you look at her code (it's pretty short), her grid uses percentage widths for columns and her template defines either a fixed or a liquid layout.
And her point that styles should be context-independent (CSS modules like legos, she says somewhere) is useful regardless of what designs you use.
Plus, I wonder along with a commenter on her blog... how much does her emphasis on grids limit (which of) her recommendations for those of us who use fluid designs?