prova cosi





inizio prova layer</p>

<div id="sp1" style="position:relative;background-color:black;width:490px;height:1px; line-height:0px;"></div>
<input type="button" onclick="sparisce()" value="sparisce">
<input type="button" onclick="ritorna()" value="ritorna">




fine prova layer</p>
<script language="JavaScript" type="text/javascript">

function sparisce(){
document.getElementById('sp1').style.visibility="h idden";
}
function ritorna(){
document.getElementById('sp1').style.visibility="v isible";
}



</script>