width:600px; height:400px; position:absolute; top:50%; left:50%; margin:-200px 0 0 -300px;
esempio:
<div style=" height:300px; width:600px; margin:-150px 0 0 -300px; position:absolute; top:50%; left:50%; background-color: #ffffcc;" >
<h1>Ciao sono un DIV allineato al centro</h1>
<p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry' s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. ...</p>
<p>Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry' s standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. ...</p>
</div>
