function textSize(dir) {
  var children = $A($("bodyText").childNodes);
  children.each(function(child) {
    var fs = child.style.fontSize;
    if (!fs) {    fs = "12px";  lh = "15px";  }
    // remove px
    var fontSize = parseInt(fs.substring(0,fs.indexOf("px")));
    var lineHeight = parseInt(lh.substring(0,lh.indexOf("px")));
    if (dir == 'up') {
      fontSize+=2;
      lineHeight+=2;
    } else {
      fontSize-=2;
      lineHeight-=2;
    }
    child.style.fontSize = fontSize+'px';
    child.style.lineHeight = lineHeight+'px';
  }); 
}