body {
    margin: 0;
    padding: 0;
    background-image: url('pexels-matt-g-623574593-18045900.jpg');
    background-size: cover;
    background-position: center center;
    background-repeat: no-repeat;
    background-attachment: fixed; /* optional */
    background-color: #cccccc;
}

body::before {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.3); /* Anpassung der Überlagerung */
    z-index: -1;
}