Top Shadow

Shadow along the top edge of the website, like this:

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;
}

Reference URL