CSS3 #loading overlay
<style type="text/css">
#loading{
position:fixed;
top:0;
left:0;
width:100%;
height:100%;
background:#e6e6e6;
opacity:.8;
-webkit-transition: visibility .8s linear;
z-index: 10;
}
#loading span{
height:80px;
width: 200px;
background-color:#000;
color:#fff;
font-size: 2.6em;
text-align:center;
position:absolute;
top: 100px;
margin-left: -100px;
left:50%;
font-family: verdana;
border-radius: 8px;
line-height: 80px;
padding:10px;
opacity: .9
}
</style>
<div id="loading">
<span>loading...</span>
</div>