var min=8;
var max=18;
function increaseFontSize() {
   var p = document.getElementsByTagName('p');
   for(i=0;i<p.length;i++) {
      if(p[i].style.fontSize) {
         var s = parseInt(p[i].style.fontSize.replace("px",""));
		 var h = parseInt(p[i].style.lineHeight.replace("px",""));
      } else {
         var s = 12;
		 var h = 16;
      }
      if(s!=max) {
         s += 1;
		 h += 1;
      }
      p[i].style.fontSize = s+"px";
	  p[i].style.lineHeight = h+"px";
   }
}
function decreaseFontSize() {
   var p = document.getElementsByTagName('p');
   for(i=0;i<p.length;i++) {
      if(p[i].style.fontSize) {
         var s = parseInt(p[i].style.fontSize.replace("px",""));
		 var h = parseInt(p[i].style.lineHeight.replace("px",""));
      } else {
         var s = 12;
		 var h = 16;
      }
      if(s!=min) {
         s -= 1;
		 h -= 1;
      }
      p[i].style.fontSize = s+"px"
	  p[i].style.lineHeight = h+"px"
   }   
}