Styling swatches images

Hi,
First – I have in the backend stated that the hoovering over an variation will result in that the variation are zoomed in (getting two times larger). The first problem was that the z-index was wrong but I solved it by putting .vi-wpvs-option-wrap:hover{z-index:9999} into custom css. However the borders from the images below are still showing a little inside the hoovered item. I tried to remove the spacing around the zoomed in variation image by adding padding:0 inside the styling above but it didn’t help. What can I do?
Second – When the image (thumbnail) are zoomed in it gets a little unsharp. Could one load medium sized images into the swatches instead of the thumbnails? I have done it by changing in the php code but if it’s possible in backend it’s of course much better.