Basic Countdown
<h3 class="countdown-basic font-weight-light" data-countdown="2021/12/31"></h3>
Legacy Countdown
<div class="countdown" data-countdown="2021/12/31"></div>
<h3 class="countdown-basic font-weight-light" data-countdown="2021/12/31"></h3>
<div class="countdown" data-countdown="2021/12/31"></div>