function showlayer(div_id){
document.getElementById("login_form").style.visibility = "visible";
document.getElementById("login_form").style.display = "block";
document.getElementById("login_link").style.visibility = "hidden";
document.getElementById("login_link").style.display = "none";
document.getElementById("register_link").style.visibility = "hidden";
document.getElementById("register_link").style.display = "none";
}