The initial canvas for content in a SiteBuiler "page" is transparent, letting the body color show through. The Edit:background menu controls it. Just below that is Edit:Page Properties, which has no background color/image controls, and since background was set in Edit background, it seems likely that both refer to "page".

There is another "Change Background" option in the page context menu, (select the page itself and right click, 4th item down). However both background setting actually refer to the tag style.

To display content in a "page" narrower than full screen width, with a background that differs from the body background, the tag which matters is .* The setting for the root div can be controlled by inserting css in the context menu html head. Unfortunately for the non-css user, if there is a menu item for what is normally considered "page" vs "body" it is not apparent.

Drag and drop can change the width of the root div, and it would be possible to insert an image behind the main content (use Arrange:Send Backward menu to push it behind content text and images), but that is a clumsy solution to a common task. And to expect users of this type of template software to develop the css skills to solve it with the head html insert negates one of the reasons they use it.

It would make more sense to eliminate the confusing mixture of body tag styling next to controls that are labeled "page", and differentiate the two concepts for SiteBuilder users. They are capable of distinguishing their content from the canvas that it sits on. Sitebuilder's pervasive use of Page to sometimes refer to body, and sometimes to content is not helpful.

*Perhaps there is a way to set the style of the centerwrapper to show behind the main root div, but when it displays around and behind the root div, if the root div is transparent what shows though is not the color of the center wrapper, but background set in the body tag.