responsive scaling

[Steven Vachon]

This is a feature request.

When creating responsive sprites for hi-res "retina" screens, each image is twice the size and then scaled down in CSS. This process is extremely painful to do manually, but the only other current way is to use bloated frameworks. If you were to provide a solution allowing us to specify a "CSS size" for each image in the sprite, it could calculate the positions and sizes for us.

For an example of this, check out:
http://stackoverflow.com/questions/3768739/css-sprites-with-dynamic-sizing#answer-3768997