index.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width,user-scalable=no,initial-scale=1">

    <title>Hello World</title>

    <style>
      body {
        border: 1px solid black;
      }
    </style>

    <!-- Inline scripts are forbidden in Firefox OS apps (CSP restrictions),
         so we use a script file. -->
    <script src="app.js" defer></script>

  </head>

  <body>
    <!-- This code is in the public domain. Enjoy! -->
    <h1>Hell</h1>
    <button type=button onclick="left()">left_button</button>
    <button type=button onclick="start()">start_button</button>
    <button type=button onclick="right()">right_button</button>
    <div id="field"></div>
    <div id="cur_field"></div>
    <audio src="./kick0.wav" preload id="kick0"></audio>
  </body>

</html>