div#calculator {
    position: fixed;
    top: 0;
    left: 0;
    z-index: 1031;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.5);
	display: none;
}

div#calculator .cbox{
    display:table;
    margin: 20px auto;
    background-color:white;
    padding: 20px;
}