Hi Mark,
I took a look at the site and the WYSIWYG background is white. I think you may be experiencing a caching issue. Do you have these values set to false in your user.config? If not, add them and then open your web.config, add a space to one of the comment sections and save it (this will cause your app pool to recycle). After doing this, if the WYSIWYG still has the gray background, clear your browser cache. If none of this fixes the issue, please let me know what browser you are using so I can test it.
HTH,
Joe D.