How to Center items in a Grid Options

[chome4]

Got this image array within a grid I got from a template:

http://test.ericfinlayartist.co.uk/

As you can see, the images aren't aligned centrally either on a full-sized screen or a smaller device.

I've tried to center the images inside the container/s but nothing.

Can someone look at the code and tell me how to centre these two colums of images.

Thanks in advance....

Files:
https://my.pcloud.com/publink/show?code=XZF...MlWPDlf6mqiwLoy