displayNewMark = function() {
  if (!document.getElementsByTagName) return;
 
  // passage time
  var passageTime = 168;
 
  // display mark
  var mark = 'New!!';
 
  var currentDate = new Date();
  var elements = document.getElementsByTagName('span');
  for (var i = 0, len = elements.length; i < len; i++) {
    if(elements[i].className == 'new') {
      var time = elements[i].firstChild.nodeValue.split(':');
      var entryDate = new Date(time[0], time[1]-1, time[2], time[3], time[4], time[5]);
      var currentTime = (entryDate.getTime () - currentDate.getTime())/(60*60*1000);
      currentTime = Math.ceil(currentTime);
      if(-currentTime <= passageTime){
        elements[i].innerHTML = mark;
        elements[i].style.display = 'inline';
      }
    }
  }
};