Transpose min/max values

[theorosendorf]

Would be great to be able to transpose the min/max values so the scaling effect was reversed for each of the metrics individually (size, leading, weight, etc).

[theorosendorf]

From @tinymachine at #21 (comment)

So min and max values for font-size, line-height, and grade are all dependent calculated based on container width, right? I'll call these former three attributes 'dependent attributes'. From an API perspective, what if you simply handled transposing based on whether the min or max value of these dependent attributes is larger? That is, if max > min, the relationship to container width is direct; if min > max, it's inverse.