That's the trouble with open forums, people often don't do as you expect or want them to. You might not be interested, but others may be, or they can just politely ignore my comment.
I just preferred to get a technical solution if someone feels invited to spend a thought on this.
How about a new thread on that matter?

Maybe clearer for you, but it has no relevance to how a page is aligned.
It definedly has a relevance as stated several times before in this thread.
If margin is 100% then a centrally aligned page gives you two times 50% which may or may be not what you want.
Off-center gives you 100%.