Not sure if I completely understood what you are asking for. I think you have an SVG image with all the states of the USA and try to use (inline) CSS to "highlight" one or more of those states?
If so, traditional methods will not work. JavaScript is not able to modify images, neither is CSS, AFAIK. The only way that I would know is to read in the SVG more or less byte for byte and base64-encode it after you have altered the image via JavaScript, then create an Image and set the source using a data URI.
There are a couple of encryptors in the Web. I suggest looking into the JSXGraph, specifically the JSXCompressor or something of that nature. Also there are some libraries to edit images, like PNGlib, although it is not quite what you are looking for. Try Google. But honestly, I don't feel like googling hours for you now by myself...
Hope I at least gave you a kick into the right direction.