Hi,
Yeah sure you could adjust size of popup box and image. It's just a little fiddly because you have to account for the container and the image within it but definitely achievable.
For instance below is an example piece of code which adjusts the proportions by around half:
#lightbox-container-image-box {
left: -280px;
height: 320px !important;
width: 420px !important;
}
#lightbox-container-image-data-box {
position: relative;
left: -280px;
width: 400px !important;
}
#lightbox-image {
width: 400px !important;
height: 300px !important;
}
You can play around with different dimensions if you wish or how far left you want to move the popup etc
If you wanted to use the above suggestion simply replace all of the contents of the wp_eStore_custom_style.css with the code given.