#mask{
        position:absolute; /* important */
        top:0px; /* start from top */
        left:0px; /* start from left */
        height:100%; /* cover the whole page */
        width:100%;  /* cover the whole page */
        display:none; /* don't show it '*/
/* styling bellow */
        background-color: black;
}

.modal_window{
        position:absolute; /* important so we can position it on center later */
        display:none; /* don't show it */
/* styling bellow */
        color:white;
}

/* style a specific modal window  */
#modal_window{
        padding:50px;
        border:1px solid gray;
        background: #246493;
        color:black;
}