index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Clock</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
    <div class="clock">
     <div class="t-box"><p class="time" id="date"></p><p class="time-subtitle">Date</p></div>
     <div class="t-box"><p class="time" id="hour"></p><p class="time-subtitle">Hours</p></div>
     <div class="t-box"><p class="time" id="min"></p><p class="time-subtitle">Minutes</p></div>
     <div class="t-box"><p class="time" id="sec"></p><p class="time-subtitle">Seconds</p></div>
     <div class="t-box"><p class="time" id="millisec"></p><p class="time-subtitle">ms</p></div>
    </div>
    <script src="mainscript.js"></script>
</body>
</html>