function change_user(){
if (document.login.user.value=="Username") {document.login.user.value="";}
}
function change_pw(){
if (document.login.pass.value=="Passwort") {document.login.pass.value="";};
}
function blur_user(){
if (document.login.user.value=="") {document.login.user.value="Username"};
}
function blur_pw(){
if (document.login.pass.value=="") {document.login.pass.value="Passwort"};
}