[Dilettante_Pro]

<style>
.timer_style {
    float:left; 
    border:1px solid black;
}
</style>
<div id="clockdiv" class="timer_style" data-stop="900">
  <div><span class="days"></span><div class="smalltext">Дней</div></div>
  <div><span class="hours"></span><div class="smalltext">Часов</div></div>
  <div><span class="minutes"></span><div class="smalltext">Минут</div></div>
  <div><span class="seconds"></span><div class="smalltext">Секунд</div></div>
</div>
<div id="clockdiv1" class="timer_style" data-stop="100">
  <div><span class="days"></span><div class="smalltext">Дней</div></div>
  <div><span class="hours"></span><div class="smalltext">Часов</div></div>
  <div><span class="minutes"></span><div class="smalltext">Минут</div></div>
  <div><span class="seconds"></span><div class="smalltext">Секунд</div></div>
</div>

<script type="text/javascript">
function getTimeRemaining(endtime) {
  var t = Date.parse(endtime) - Date.parse(new Date());
  var seconds = Math.floor((t / 1000) % 60);
  var minutes = Math.floor((t / 1000 / 60) % 60);
  var hours = Math.floor((t / (1000 * 60 * 60)) % 24);
  var days = Math.floor(t / (1000 * 60 * 60 * 24));
  return {
    'total': t,
    'days': days,
    'hours': hours,
    'minutes': minutes,
    'seconds': seconds
  };
}

function initializeClock(id, endtime) {
  var clock = document.getElementById(id);
  var daysSpan = clock.querySelector('.days');
  var hoursSpan = clock.querySelector('.hours');
  var minutesSpan = clock.querySelector('.minutes');
  var secondsSpan = clock.querySelector('.seconds');

  function updateClock() {
    var t = getTimeRemaining(endtime);
    daysSpan.innerHTML = t.days;
    hoursSpan.innerHTML = ('0' + t.hours).slice(-2);
    minutesSpan.innerHTML = ('0' + t.minutes).slice(-2);
    secondsSpan.innerHTML = ('0' + t.seconds).slice(-2);
    if (t.total <= 0) {clearInterval(timeinterval);}
  }
  updateClock();
  var timeinterval = setInterval(updateClock, 1000);
};

var clocks = document.querySelectorAll('.timer_style');

clocks.forEach(function (elem) {
   initializeClock(elem.id , new Date(Date.parse(new Date()) + elem.getAttribute('data-stop') * 1000));
});

</script>