Product Image Background/border/grid

I can't for the life of me figure out where I need to change the background color around my main image. Been playing around with Firebug for an hour but it will not give me the location of what needs to be changed. My website has a black background but would like the background for the grid around the main preview image be white since the black "bars" next to the image are confusing some people into thinking they are part of the image. See example. I want the entire box with the white border to white so it blends in with the main image and doesn't look like the black bars on the left and right of the image are part of the product. How do I do that?

Please add the following rule to the CSS section of the theme editor:

.ty-product-img {
    background: white;