body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-color: rgba(0, 0, 0, 0.5);
    z-index: -1;
    transition: background-color 0.5s ease-in-out;
}

body.dark-theme::before {
    background-color: rgba(0, 0, 0, 0.7);
}