I have it ingrained in me that css identifiers (classes/ids) should be semantic to the data and not the visual side.
I know this isn't a big factor for some people, and on that front it looks super and design philosophy is very cool (lightweight is great!).
At first it seemed to me that Responsive did not use mixings, but this is not completely true. The utilities are all mixings but the partials are fixed instantiation of mixins (`.row { @extend .clearfix; }`).
In my perfect world it `.row` would be `.row { @extend row; }`, so I can be able to avoid using the "row" class altogether and do things like `#definitions > p { @extend row }`.
We do it this way, it was a piece of cake to set up the initial mixins and we haven't had to think about them since. Just reference something like .column(3) and bam, that element spans 3 columns.
That aside, this looks like a nice alternative to Bootstrap/Foundation.