This handy technique will add a shadow to the top of your page:

/* top shadow */  
body:before {  
    content: ""; 
    position: fixed; 
    top: -10px; 
    left: 0; 
    width: 100%; 
    height: 10px;  
    -webkit-box-shadow: 0px 0px 10px rgba(0,0,0,.8); 
    -moz-box-shadow: 0px 0px 10px rgba(0,0,0,.8); 
    box-shadow: 0px 0px 10px rgba(0,0,0,.8);  
    z-index: 100; 
}

CSS from genelocklin.

Published on February 15, 2011