window.addEvent('domready', function() {
  myBox('myBox', 'closeBox');
});
var myBox = function(target, closeBtn){
 if($(target)){
  var maskHeight = $(document).getHeight();
  var maskWidth = $(window).getWidth();
  $(target).setStyles({'width':maskWidth,'height':maskHeight});
  $(closeBtn).getElement('a').addEvent('click', function(){
   $(target).setStyle('display', 'none').dispose();
   $('intro').setStyle('display', 'none').dispose();
  });
 }
}