Make Preview Popup Image Responsive

[likestuff]

Hi there,

I'm trying to get the image to be responsive in the modal popup but no matter what I try I just can't get it to work. The CSS below is what I'm using. What am I doing wrong please?

Also, is there an option to not use an iframe, I think that's what making it more difficult to style.

iframe#pdCategoryModalIframe img {
max-width: 100%;
width: 100%;
height: auto;
margin: 0 auto;
}

Thanks!