function newImage(arg) {
        if (document.images) {
                rslt = new Image();
                rslt.src = arg;
                return rslt;
        }
}

function changeImages() {
        if (document.images && (preloadFlag == true)) {
                for (var i=0; i<changeImages.arguments.length; i+=2) {
                        document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
                }
        }
}

var preloadFlag = false;
function preloadImages() {
        if (document.images) {
                navi_01_over = newImage("imgs/navi_01-over.jpg");
                navi_02_over = newImage("imgs/navi_02-over.jpg");
                navi_03_over = newImage("imgs/navi_03-over.jpg");
                navi_04_over = newImage("imgs/navi_04-over.jpg");
                navi_05_over = newImage("imgs/navi_05-over.jpg");
                navi_06_over = newImage("imgs/navi_06-over.jpg");
                navi_07_over = newImage("imgs/navi_07-over.jpg");
                navi_08_over = newImage("imgs/navi_08-over.jpg");
                preloadFlag = true;
        }
}

function increase(id) { 
    window.document.getElementById(id).style.MozOpacity = 1.0; 
    window.document.getElementById(id).style.filter = "alpha(opacity=100)";
; 
	
} 
function decrease(id) { 
    window.document.getElementById(id).style.MozOpacity = 0.5; 
    window.document.getElementById(id).style.filter = "alpha(opacity=50)";
}