.mitte {display: flex; justify-content:center ;align-items: center;}
body {
    margin: 0;
    background: white;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen,
      Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
  }
  
  header {
    padding-top: 24px;
    padding-bottom: 24px;
  }