function changeFont(font) {
    var ss = document.all ? document.styleSheets[0].rules : document.styleSheets[0].cssRules;  //ie : ff
    ss[0].style.fontFamily = font;
}
function changeFontSize(size) {
    /*if (size == 1)
        size = 12;
    else if (size == 2)
        size = 16;
    else if (size == 3)
        size = 20;*/
    var ss = document.all ? document.styleSheets[0].rules : document.styleSheets[0].cssRules;  //ie : ff    
    ss[0].style.fontSize = size + "px";
}