var cursize = 1;

function schriftgroesse() {
  if (cursize == 0) {
    document.body.style.fontSize = "10px";
    cursize = cursize + 1;
    return;
  }

  if (cursize == 1) {
    document.body.style.fontSize = "12px";
    cursize = cursize + 1;
    return;
  }

  if (cursize == 2) {
    document.body.style.fontSize = "15px";
    cursize = 0;
    return;
  }
}

function clearfield(field, defaulttext) {
  if (field.value == defaulttext) {
    field.value = '';
  }
}

function fillfield(field, defaulttext) {
  if (field.value == '') {
    field.value = defaulttext;
  }
}