Google Navbar wieder einblenden

Zeige Nav

HTML-Code:
<script type="text/javascript">
function an(){
document.getElementById('Navbar1').style.display = "block" ;
document.getElementById('sso').style.display = "none" ;
}
</script>
<div style="margin-top:30px">
<a id="sso" href="javascript:an();">Zeige Nav</a>
</div>