div.play_button {
    position: absolute;
    left: 0px;
    top: 0px;
    width: 100%;
    height: 100%;
    overflow: hidden;
}

div.play_button div {
    position: absolute;
    left: 0px;
    top: 0px;
    width: 100%;
    height: 100%;
    overflow: hidden;
    background: url(play.png) no-repeat center center; 
}