Hmm this never got answered...

I would like to know this as well, I do not like partial width themes and would like igcstation to fill the whole page.

Well I found the solution for this for another theme and it worked great so I will lay it on here too.

Open the header.html and change the very first table width from 80% to 99 or 100%.

Credit to: coldblooded for this answer in that other post.