.backgroundDiv {
    width: 100%; 
    height: 100%; 
    position: fixed; 
    left: 0px; 
    top: 0px; 
    z-index: 999;
    background-color: #252525;    
    opacity: .5;
    display: none;
    background-image: url(images/Rhombus.gif);
    background-size: 128px;
    background-position: center;
    background-repeat: no-repeat;
}