function nav_on(id) {
    doc = document.getElementById(id);
    doc.style.background="#192a4a url('images/tile_nav_on.gif') repeat-x 0 0";
    doc.getElementsByTagName('a')[0].style.color="#9ca9d2";


}

function nav_off(id) {
    doc = document.getElementById(id);
    doc.style.background="#2c4064 url('images/tile_nav.gif') repeat-x 0 0";
    doc.getElementsByTagName('a')[0].style.color="#fff";
}