Many people agree, that the "body" tag should be treated as a top-level block element: the "box" everything is in. Another viewpoint is that it is a syntactical (rather than structural) element, and so doesn't have any "dimensions" in and of itself.

Since there is no agreement, the solution is treat the body element like an "open" and "close" statement that has nothing to do with position, size, etc. and to either put everything within a table, or a DIV.