var layername;

function onmenu(name){
document.images[name].src="img/"+name+"_akt.jpg";
layername="lay"+name;
if (document.getElementById){
document.getElementById(layername).style.visibility="visible";
}
if (document.layers){
document.layers[layername].visibility="show";
}
}

function offmenu(name){
document.images[name].src="img/"+name+".jpg";
layername="lay"+name;
if (document.getElementById){
document.getElementById(layername).style.visibility="hidden";
}
if (document.layers){
document.layers[layername].visibility="hide";
}
}