I don't see how, you're still having to calculate percentages at each break point. Maybe I'm missing something but it seems it's only saving you calculating th

I don't see how, you're still having to calculate percentages at each break point. Maybe I'm missing something but it seems it's only saving you calculating the margin/padding. If you're using a tool to calculate the percentages for you such as http://semantic.gs/ http://semantic.gs/ I don't see how you couldn't do the same with less calculation and much less CSS.