Page Scaling In Browser

Can anyone help me figure out why this Print Store page is not scaling to be centred when on a desktop browser?

I thought I had this figured out but when I maximised my browser it stays left of centre. The three images have links to other pages on my website so I have them as 3 seperate image blocks. I have maxed out my 'Site Width' setting which helped a bit but it's still not enough.

I've attached a gallery page as well which doesn't have this problem.