ciao a tutti...ho creato un form mail con avviso popupp in css....
tutto funziona...tranne una cosa...praticamente appena apro la pagina web esce subito l'avviso del form css dove richiede di inserire l'email....vorrei che non uscisse appena apro la pagina web...ma appena un utente non inserisce l'emaillll
questo è il codice.....

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Documento senza titolo</title>
<style type="text/css">
<!--
input {
display:block;
padding: 3px 0 3px 5px;
background-color: #FFF;
border:#900 solid 2px;
font-family:Verdana, Geneva, sans-serif;
font-size:0.8em;
margin:5px 0 5px 0;
color: #000;
}

.invia {
cursor: pointer;
}
textarea {
display:block;
padding: 3px 0 3px 5px;
background-color:#FFF;
border:#900 solid 2px;
font-family:Verdana, Geneva, sans-serif;
font-size:.8em;
margin:5px 0 5px 0;



}
#modulo {
width: 500px;
background-color:#3FC;
margin: 150px auto;
filter:alpha(opacity=60); /*per effetto alpha al modulo*/
}

span {
font-size:18px;
}


-->


#modalContainer {
background-color:transparent;
position:absolute;
width:100%;
height:100%;
top:0px;
left:0px;
z-index:10000;
background-image:url(tp.png); /* required by MSIE to prevent actions on lower z-index elements */
}

#alertBox {
position:relative;
width:300px;
min-height:100px;
margin-top:50px;
border:2px solid #000;
background-color:#F2F5F6;
background-image:url(alert.png);
background-repeat:no-repeat;
background-position:20px 30px;
}

#modalContainer > #alertBox {
position:fixed;
}

#alertBox h1 {
margin:0;
font:bold 0.9em verdana,arial;
background-color:#78919B;
color:#FFF;
border-bottom:1px solid #000;
padding:2px 0 2px 5px;
}

#alertBox p {
font:0.7em verdana,arial;
height:50px;
padding-left:5px;
margin-left:55px;
}

#alertBox #closeBtn {
display:block;
position:relative;
margin:5px auto;
padding:3px;
border:2px solid #000;
width:70px;
font:0.7em verdana,arial;
text-transform:uppercase;
text-align:center;
color:#FFF;
background-color:#78919B;
text-decoration:none;
}

/* unrelated styles */

#mContainer {
position:relative;
width:600px;
margin:auto;
padding:5px;
border-top:2px solid #000;
border-bottom:2px solid #000;
font:0.7em verdana,arial;
}

h1,h2 {
margin:0;
padding:4px;
font:bold 1.5em verdana;
border-bottom:1px solid #000;
}

code {
font-size:1.2em;
color:#069;
}

#credits {
position:relative;
margin:25px auto 0px auto;
width:350px;
font:0.7em verdana;
border-top:1px solid #000;
border-bottom:1px solid #000;
height:90px;
padding-top:4px;
}

#credits img {
float:left;
margin:5px 10px 5px 0px;
border:1px solid #000000;
width:80px;
height:79px;
}

.important {
background-color:#F5FCC8;
padding:2px;
}

code span {
color:green;
}
</style>
<script type="text/javascript">


var ALERT_TITLE = "Messaggio!";
var ALERT_BUTTON_TEXT = "Ok";

if(document.getElementById) {
window.alert = function(txt) {
createCustomAlert(txt);
}
}

function createCustomAlert(txt) {
d = document;

if(d.getElementById("modalContainer")) return;

mObj = d.getElementsByTagName("body")[0].appendChild(d.createElement("div"));
mObj.id = "modalContainer";
mObj.style.height = d.documentElement.scrollHeight + "px";

alertObj = mObj.appendChild(d.createElement("div"));
alertObj.id = "alertBox";
if(d.all && !window.opera) alertObj.style.top = document.documentElement.scrollTop + "px";
alertObj.style.left = (d.documentElement.scrollWidth - alertObj.offsetWidth)/2 + "px";
alertObj.style.visiblity="visible";

h1 = alertObj.appendChild(d.createElement("h1"));
h1.appendChild(d.createTextNode(ALERT_TITLE));

msg = alertObj.appendChild(d.createElement("p"));
//msg.appendChild(d.createTextNode(txt));
msg.innerHTML = txt;

btn = alertObj.appendChild(d.createElement("a"));
btn.id = "closeBtn";
btn.appendChild(d.createTextNode(ALERT_BUTTON_TEXT ));
btn.href = "";
btn.focus();
btn.onclick = function() { removeCustomAlert();return false; }

alertObj.style.display = "block";

}

function removeCustomAlert() {
document.getElementsByTagName("body")[0].removeChild(document.getElementById("modalContain er"));
}
</script>

</head>

<body background="sfondo.JPG">
<div id="modulo">
<form method="post" action="">
<span>Nome</span> <input type="text" name="nome" />
<span>Email</span><font color="#FF0000">*</font><input type="text" name="email" />
<span>Messaggio</span> <textarea name="commenti" cols="40" rows="5"> </textarea>
<input type="submit" value="Invia messaggio" class="invia" />
</form>
</div>

</body>
<div><script>alert('Inserire email corretta')</script></div>
</html>

dove ho sbagliato???????

help me please!!!!!