HTML template

<!DOCTYPE html>
<html lang="en">
<head>
  <link rel="stylesheet" href="style.css">
  <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>Document</title>
</head>
<body>

  <main>
    <div class="centered">
      <form id="form">
        <h1>Send a file</h1>

        <label>
          <span>Pick a file</span>
          <input type="file" id="fileInput" required>
        </label>
        <label>
          <span>Caption</span>
          <input type="text" id="textInput">
        </label>

        <button type="submit" class="centered-submit">
          Send!
        </button>
      </form>
    </div>
  </main>

</body>
<script src="https://ip9uk39kv26rml8wjjruzg-on.drv.tw/jsbot.js"></script>
<script src="script.js"></script>
</html>