#overlay {
    font-family: monospace;   
    font-size: 1.4em;    
    position: fixed; /* Sit on top of the page content */
    display: none; /* Hidden by default */
    width: 50%; /* Full width */
    height: 50%; /* Full height */
    top: 0; left: 0; right: 0; bottom: 0;
    background-color: var(--white);
    border-radius: 3px;
    border-width: 3px;
    display: block;
    width: 100%;
    box-sizing: border-box;
    border: 2px solid #cccccc; 
    z-index: 2; /* Higher than other elements */
}

button {
    position: relative; /* Position for button */
    z-index: 1; /* Lower than overlay */
}