firebase/example/firestore/index.html

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Firestore demo</title>
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css"
        integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
  <style type="text/css">
    ul {
      list-style: none;
      margin: 0;
      padding: 0;
    }

    li {
      margin: 0;
      padding: 4px 2px;
      border-bottom: 1px solid silver;
      overflow: auto;
    }

    #messages_wrapper {
      width: 500px;
      margin-bottom: 15px;
      overflow-y: auto;
    }

    #messages a {
      float: right;
      margin-left: 10px;
    }

    #new_message {
      width: 350px;
    }
  </style>
</head>
<body>
<div class="container">
  <h1>Firestore demo</h1>
  <div id="messages_wrapper">
    <ul id="messages"></ul>
  </div>
  <form id="new_message_form">
    <input type="text" placeholder="Your Message" id="new_message" disabled>
    <input type="submit" value="Send" id="submit" disabled>
    <button id="disable">disable network</button>
    <button id="enable" hidden>enable network</button>
  </form>
</div>
<script src="https://www.gstatic.com/firebasejs/8.10.0/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/8.10.0/firebase-firestore.js"></script>
<script defer src="index.dart.js" type="application/javascript"></script>
</body>
</html>