var min=10;
var max=20;

function increaseFontSize() {
   var p = document.getElementsByTagName('a','font');
   for(i=0;i<p.length;i++) {
      if(p[i].style.fontSize) {
         var s = parseInt(p[i].style.fontSize.replace("pt",""));
      } else {
         var s = 10;
      }
      if(s!=max) {
         s += 2;
      }
      p[i].style.fontSize = s+"pt"
   }
}
function decreaseFontSize() {
   var p = document.getElementsByTagName('a','font');
   for(i=0;i<p.length;i++) {
      if(p[i].style.fontSize) {
         var s = parseInt(p[i].style.fontSize.replace("pt",""));
      } else {
         var s = 12;
      }
      if(s!=min) {
         s -= 2;
      }
      p[i].style.fontSize = s+"pt"
   }   
}