function open_menu()
{if (navigator.appName.indexOf("Microsoft")!= -1) {
 document.center_menu.style.height="148px";
}else{
 document.getElementById('center_menu').style.height="148px";}
}
function close_menu()
{if (navigator.appName.indexOf("Microsoft")!= -1) {
 document.center_menu.style.height="24px";
}else{
 document.getElementById('center_menu').style.height="24px";}
}