Блондинка,
theme: "black" можно убрать.
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/time-to@1.2.3/timeTo.css">
<script src="https://cdn.jsdelivr.net/npm/time-to@1.2.3/jquery.time-to.js"></script>
<script>
$(function() {
var clock = $('.your-clock').timeTo({theme: "black"})
});
</script>
</head>
<body>
<div class="your-clock"></div>
</body>
</html>