function TextResize(size) {
  var fosi = document.body.style.fontSize;
  if(fosi == "") fosi = "small";
  if(size == 0)  fosi = "small";
  else {
    switch (fosi) {
      case "x-small":
      if(size>0) fosi = "small";
      break;
      case "small":
      if(size>0) fosi = "medium";
      if(size<0) fosi = "x-small";
      break;
      case "medium":
      if(size>0) fosi = "large";
      if(size<0) fosi = "small";
      break;
      case "large":
      if(size>0) fosi = "x-large";
      if(size<0) fosi = "medium";
      break;
      case "x-large":
      if(size<0) fosi = "large";
      break;
    }
  }
  document.body.style.fontSize = fosi;
}