Disable background box displayed behind caption on a nivo slider page.

My website (southbeach94158.com) uses a nivo slider on its homepage.
It shows two slide pictures with caption in white float box.
Nivo Slider was pre-installed with wordpress theme I purchased.
I’m not sure what version of nivo slider I have.

How can I disable (or make transparent) the white background box that appears behind/with the caption?

I’ve gone through the theme code, but could not find the code that creates the text background box. Please help…