Can we change the default width?

Hi guys, me again!

We’re currently in negotiations with various ad agencies about adding skyscraper ads to the site. We have a couple of questions, as they are rather finicky about the sizes and thing…

At the moment, the default size of our main body is this:

http://imgur.com/wLi6nTV,b9ixYpB

That’s a little zoomed-in, for the purposes of ad agencies, who require that ads be placed above the fold.

What we would be after is setting a default view more like this:

http://imgur.com/b9ixYpB

It’s a small difference, but believe me – it makes a HUGE impact on whether or not ad agencies deal with us. Is there a way that we can set the default size of how our pages appear?

Thanks in advance!