var max=16;
var changed=false;
var min=10;

function increaseFontSize() {

arrIncreaseFontSize( document.getElementsByTagName('a'));
arrIncreaseFontSize( document.getElementsByTagName('p'));
arrIncreaseFontSize( document.getElementsByTagName('td'));
arrIncreaseFontSize( document.getElementsByTagName('body'));
<!--changed=True;-->
}
function arrIncreaseFontSize(p,init){
   for(i=0;i<p.length;i++) {
      if(p[i].style.fontSize) {
         var s = parseInt(p[i].style.fontSize.replace("px",""));
      } else {
         var s = 13;
      }
      if(s<max) {
         s += 1;
      }
      p[i].style.fontSize = s+"px";
   }

}



function decreaseFontSize() {
<!--if(changed){-->
arrDecreaseFontSize( document.getElementsByTagName('a'));
arrDecreaseFontSize( document.getElementsByTagName('p'));
arrDecreaseFontSize( document.getElementsByTagName('td'));
arrDecreaseFontSize( document.getElementsByTagName('body'));
}<!--}-->
function arrDecreaseFontSize(p,init){
   for(i=0;i<p.length;i++) {
      if(p[i].style.fontSize) {
         var s = parseInt(p[i].style.fontSize.replace("px",""));
      } else {
         var s = 11;
      }
      if(s>min) {
         s -= 1;
      }
      p[i].style.fontSize = s+"px";
   }

}

function resetFontSize(){
location.reload(true);
}