body {
    background-attachment: fixed;
    background-image: url("../img/lenteland.jpg");
    background-position: center top;
    background-repeat: no-repeat;
    background-size: 100% 100%;
    color: #ffffff;
    font-family: "Trebuchet MS",Geneva,Arial,Helvetica,SunSans-Regular,sans-serif;
    font-size: 14px;
    line-height: 19px;
    margin: 0;
    padding: 0;
}

.centerdiv {
  position: fixed; /* or absolute */
  top: 50%;
  left: 50%;
  /* bring your own prefixes */
  transform: translate(-50%, -50%);
  
  font-family: "Trebuchet MS",Geneva,Arial,Helvetica,SunSans-Regular,sans-serif;
  font-size: 500%;
}