Remove space between image and border in spree_fan

Question

I'm using spree and spree_fancy to create an e-commerce in Rails.

I'm stuck when trying to change some of the design aspects of the spree_fancy gem. At this point I want to use product images with some background (not transparent), but when I use them, there is always a space between the image and the border. I want the image to perfectly fit into the border.

I assume that I would need to override some of the scss files. My attempt was to look at this file into the #main-image ID.

spree_fancy / app / assets / stylesheets / spree / fancy / components / _product_item.scss 

but I couldn't figure out how to change it. And also I don't know if this is what I need to change actually.

I'm using:

rails-4.0.2 spree-2-1-stable spree_fancy-2-1-stable

Could anyone help me out?