Таймер обратного отсчета

Простая реализация безлишних прибамбасов

HTML

<div class="Countdown" id="countdown">
    <h1>Таймер обратного отсчёта</h1>
    <figure>
        <span class="days"></span>
        <figcaption class="smalltext">Дни</figcaption>
    </figure>
    <figure>
        <span class="hours"></span>
        <figcaption class="smalltext">Часы</figcaption>
    </figure>
    <figure>
        <span class="minutes"></span>
        <figcaption class="smalltext">Минуты</figcaption>
    </figure>
    <figure>
        <span class="seconds"></span>
        <figcaption class="smalltext">Секунды</figcaption>
    </figure>
</div>

CSS

body {
    display: flex;
    width: 100%;
    height: 400
    margin: 0px;
}

.Countdown {
    display: flex;
    flex-wrap: wrap;
    justify-content: center; 
    align-items: flex-start;
    align-content: stretch;
    width: auto;
    margin: auto;
}
.Countdown h1 {
    display: block;
    width: 100%;
    margin-bottom: 7px;
    text-align: center;
    font-size: 30px;
    color: #424242;
}
.Countdown figure {
    display: block;
    margin: 0;
    padding: 10px 25px;
    text-align: center;
}
.Countdown span {
    font-size: 52px;
    font-weight: bold;
    color: #1565C0;
}
.Countdown figcaption {
    font-size: 20px;
    color: #90A4AE;
}

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);
          daysSpan.innerHTML =  "Все!!";
        }
      }

      updateClock();
      var timeinterval = setInterval(updateClock, 1000);
    }
    var deadline = new Date('2018-01-01T00:00:00');
    initializeClock('countdown', deadline);