Event.observe(window, "load", fixbg_height);
Event.observe(window, "load", fixbg_position);
Event.observe(window, "resize", fixbg_position);

function fixbg_position() {
    // Set horizontal positioning
    var bg_shift = $$("div.wrapper")[0].positionedOffset()[0];
    $(document.body).setStyle({ backgroundPosition : bg_shift + "px 0" });
}

function fixbg_height() {
    // Set middle height to align footer
    var mid_height = $$('.middle')[0].getDimensions().height;
    var new_height = (587 - (mid_height % 400)) + mid_height;
    $$('.middle')[0].setStyle({ height : new_height + "px" });
}