ciao,
il div alex non si allinea al centro, perchè?

<html>
<head>
<title>bottom</title>
<style type="text/css">
html{
height:100%;
font-family: Trebuchet MS, Lucida Sans Unicode, Arial, sans-serif;
}
body{
margin:0px;
padding:0px;
text-align:center;
height:100%;
background-color:#E2EBED;
}
#alex{
background-color: #555;
height:25px;
width:700px;
z-index:1000;
position:absolute;
bottom:0px;
left:0px;
}
</style>
</head>
<body>
<div id="alex">ciao</div>
</body>
</html>