@media (max-width:991px) {
    body.poster {
        margin-top: 10vh;
    }
}

body.poster {
    background-attachment: fixed;
}

.top-5 {
    top: 5px;
}

sectionzwei {
    display: flex;
    align-items: center;
    justify-content: center;
}

maineins {
    display: flex;
    align-items: stretch;
}