Copyleft

I am not that sensitive to copyright-related stuff. Really not.
You might do what you want. The responsive CSS framework is working, you might even use it for a web design that does not look like an archive caption from 20 yrs ago!
Just please don't sell anything (though I seriously doubt it's posiible to earn money with this substandard stuff) or claim it to be your own work. Otherwise... do what thou wilt b/c that sounds sooooo occulth and darque!