background CSS style problem

I am pretty new to web design so I have struggled with this problem for awhile
now. I have set up a background style in which an image is tiled vertically
only and then centered in the window. The background is just some colors and
lines. Then I placed a table on top with similiar colors so that they align in
the center. The design looks fine when the window is open enough so you can see
all the content of the window but when you shrink the window over the table the
background shrinks with it and it no longer aligns with the table. The website
is www.kevin.dsmithdesign.com
Any insight would be appreciated. Thank