function menuon(id){
newImage = "url(img/menubgon.png)";
document.getElementById(id).style.backgroundImage = newImage;
}
function menuoff(id){
newImage = "url(img/menubgoff.png)";
document.getElementById(id).style.backgroundImage = newImage;
}
function menuon_opp(id){
newImage = "url(img/menubgon_opp.png)";
document.getElementById(id).style.backgroundImage = newImage;
}
function menuoff_opp(id){
newImage = "url(img/menubgoff_opp.png)";
document.getElementById(id).style.backgroundImage = newImage;
}