Unnamed

<html>
<head>
<style>
  html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
  }

  #pageBlanket {
    position: absolute;
    border: thick dotted black;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    filter: alpha(opacity=55);
    -moz-opacity: .55;
    background-color:#EEE;
    z-index: 499;
  }
</style>

<title></title>
</head>
 <body>
  <div style="margin: auto; background-color: rgb(204, 204, 204); width: 403px; position: relative;">
   <p>This is opaque div. This is opaque div. This is opaque div. This is opaque div. This is opaque div. This is opaque div. This is opaque div.</p>
   <p>This is opaque div. This is opaque div. This is opaque div. This is opaque div. This is opaque div. This is opaque div. This is opaque div.</p>
   <p>This is opaque div. This is opaque div. This is opaque div. This is opaque div. This is opaque div. This is opaque div. This is opaque div.</p>
  </div>
  <input type="button"/>

  <script>
   alert("it's going to happen!");
   var blanket = document.createElement("div");
   blanket.id = "pageBlanket";
   blanket.innerHTML = "Blah!";
   document.body.appendChild(blanket);
  </script>
 </body>
</html>