var min=8;
var max=18;
function increaseFontSize() {
   var p = document.getElementsByClass('resizable');
   for(i=0;i<p.length;i++) {
      if(p[i].style.fontSize) {
         var s = parseInt(p[i].style.fontSize.replace("px",""));
      } else {
         var s = 12;
      }
      if(s!=max) {
         s += 1;
      }
      p[i].style.fontSize = s+"px"
   }
}
function decreaseFontSize() {
   var p = document.getElementsByClass('resizable');
   for(i=0;i<p.length;i++) {
      if(p[i].style.fontSize) {
         var s = parseInt(p[i].style.fontSize.replace("px",""));
      } else {
         var s = 12;
      }
      if(s!=min) {
         s -= 1;
      }
      p[i].style.fontSize = s+"px"
   }   
}

document.getElementsByClass = function(className) {
  var all = document.getElementsByTagName('*');
  var elements = new Array();
  for (var e = 0; e < all.length; e++)
    if (all[e].className == className)
      elements[elements.length] = all[e];
  return elements;
}