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

body {
    background-color: #f9e79f;
    display: flex;
    justify-content: center;
    align-items: center;
}

.mitte {
    text-align: center;
}

.mitte img {
    max-width: 300px;
    height: auto;
}

.button {
    display: block;
    max-width: 300px;
    height: auto;
    margin: 0 auto;
}