Yes.. That has been around RANDOMLY since CSB 3.
It was listed under the "known issues" that we were trying to get Globalscape to fix for version 5.
With as many pages as you have, I am surprised you have not had the problem before!
Read about it here:
http://www.samisite.com/publish/id84.htm#whitespaceMost important part of instruction from that page:
1) Preview or publish your page as usual.
2) Open up the source code to see what CSB/Trellix has generated. On the Internet Explorer toolbar, choose View > Source. Look for your background settings near the top of the source code.
3) Using the background color and/or the background image that is listed in the source code, make a css style code to match, mine is shown below. Place your code into an insert > HTML (or webgem in Trellix).
<style type="text/css">
<!--
body
{
background-image: url(4028ca03.jpg);
background-color: #FFFBF0
}
-->
</style>
4) Publish again. WHITE SPACE may be gone. WITHOUT FRAMES: mixed results
No borders OR Borders same color as body: the color you place for body replaces the ALL the white area resolving issue.
Borders different color than body: the color you place for body replaces the ALL the white area, even if your Top border is a different color! So your top border will not go all the way across the page when this FIX is put in place, but at least the rest of the white space is gone.