var size=100.01;

function resize(type){
  if      (type == '+'){ 
	if(size<121){
		size=size+10;
	}
  }else if (type == '-'){
	if(size>80){
		size=size-10;
	}
  }else{size=100.01;}
	 
  if (document.getElementsByTagName('body') != null && document.getElementsByTagName('body')[0] && size != null){
	 document.getElementsByTagName('body')[0].style.fontSize = size+'%';
  }
}