Can't control size

I’m having trouble finding a way to control the size of the window for different pages with iframe content. I have 2 different pages with the link to open iframe but when I set the options in the settings to 0 for the width and height of the iframe, it’s ignored. It says Min/Max: 0 = not set and I’m trying to control the size of the window using css for one of the pages:

.windowlarge#ob_window {
padding: 22px 0 0 20px !important;
width: 585px !important;
height: 400px !important;
overflow-x: hidden;
}

I have another slideshow that’s a different size and if I don’t control the size, a thick white border appears on the right of the window, because the white background is showing. I tried to control that too, with css, but that’s also ignored:

#ob_content {
background-color: #000000 !important;
border: 0px solid #000000 !important;
}

The main problem though is size, I don’t want any borders around the iframe, just the exact size of the image that’s in that iframe. Is there any way to control this within the link itself or with CSS so that it’s not cutting off the images? If I set a size in the settings it cuts off the images in one of the iframe windows.

Thanks!~