I’ve found the solution.
Change position from “absolute” to “fixed” for .black overlay and .messageContainer.
.black_overlay { display: none; position: fixed; top: 0%; left: 0%; width: 100%; height: 100%; background-color: black; z-index: 1001; -moz-opacity: 0.8; opacity: .80; filter: alpha(opacity=80); }
.messageContainer { display: none; position: fixed; top: 0; width: 100%; z-index: 1002; text-align: center; height: 100%; #position: fixed; overflow: hidden; }