html, body {
    height: 100%;
    margin: 0;
}

body {
    display: flex;
    flex-direction: column;
    align-items: center; /* alles horizontal zentrieren */
}

main {
    flex: 1 0 auto;
    width: 100%;
    max-width: 1200px; /* maximale Breite */
    padding: 0;
}

footer {
    flex-shrink: 0;
    background-color: #f8f9fa;
    padding: 1rem;
    text-align: center;
    width: 100%;
}

iframe {
    width: 100%;
    height: calc(100vh - 70px - 60px); /* Navbar + Footer Höhe */
    border: none;
    display: block;
    margin: 0 auto;
}

.navbar-nav {
    justify-content: center;
}