Problems with _LRG images

I've defined the image_LRG of width=600 & height=400 and so I've modified the function popupWindow(url) in includes/modules/pages/product_info/jscript_main.php
With this values.

The problem is that the function open a window of width=610 & height=440 and so there are some white border (especially the height) that I don't like.

May be there is a problem in css(?) but in stylesheet_new.css I see the definition

#headerWrapper, #contentMainWrapper, #logoWrapper, #cartBoxListWrapper, #ezPageBoxList, #cartBoxListWrapper ul, #ezPageBoxList ul, #mainWrapper, #popupAdditionalImage, #popupImage {
margin: 0em;
padding: 0em;
}

What can I do? - Thanks

p.s.
I see that while the image is loading the windows seem correct, but when all the image is loaded happen what i've told before.

The window is being resized based on "content".

If you're using v1.3.x, this resizing should be accurate, depending on which browser you're viewing it in.
Prior to v1.3, it was slightly off.

If you wish to fine-tune, play with the resize javascript in includes/modules/pages/product_image/jscript_main.php

Beware: each browser handles dimensions differently. If you go changing it to look nice in your browser, your customers may find it looks badly in their browser.
Don't mess with it if you don't have to; or be very sure to test in as many browsers as possible.

I've v1.3.0.1, but I don't see the folder "product_image" in includes/modules/pages/

Maybe that is in product_info??

Excuse me!!!!!!
I think to have found it in the "popup_image" folder.
Many thanks - Giovanni