More flexibility?

Thanks for the plugin! I took your calculations and [made a SASS mixin](https://gist.github.com/jhned/2c3fd4747b4abb87fb050a9b0822dc41) out of it.

I was running in to trouble because my use case didn't line up 100% with your intent-- I was using it as a way to make the font size of a module larger on a large handheld viewport, like from 400px to 600px. The issue was that I often wanted to reset to a smaller font-size, rather than transitioning to the "max-font-size" value.

With my mixin, you can use the fluid font size for more than one range, and the media query is scoped (using a Zurb Foundation function) to the supplied breakpoints.

Not sure if this plugin _needs_ that, but just wanted to offer my experience in return for the knowledge I got from your plugin. That calculation is intense!

Start by comparing the plugin's current responsive type behavior with the SASS mixin linked in the issue, focusing on multiple font-size ranges and breakpoint scoping. Done would require a clearly agreed change to support resetting to smaller sizes across more than one range, along with documented or tested behavior.

Written by the indexing model from the issue text.