modal dialog

HTML

<div id="main">Main Content</div>
<div id="overlay"></div>
<div id="container">
    <div id="dialog">Hello Modal Dialog!</div>
</div>

CSS

#main {
  font-size: 200%;   
}
#overlay {
  visibility: visible; /*hidden;*/
  position: absolute;
  left: 0px;
  top: 0px;
  width:100%;
  height:100%;
  z-index: 1000;
  background: gray;
  zoom: 1;
  filter: alpha(opacity=80);
  opacity: 0.8;
}

#container {
  position: absolute;
  left: 0px;
  top: 0px;
  width:100%;
  height:100%;
  z-index: 2000;
  text-align: center;
    background: #666;
}

#dialog {
  width: 480px;
  height: 300px;
  margin: 100px auto;
  border: 1px solid #000;
  padding: 15px;
  text-align: center;
  background: white;
}