 input[type="submit"] { display: block; margin-top: 1em; }
      .greeting { padding-bottom: 0.5em; }
      .messages { border-top: 1px solid black }
      .message { display: block; }
      .message span { padding-top: 0.5em; }
      .message .username { font-weight: bold; width: 100px; float: left;}
    </style>
</head>
<body>
<nav class="navbar navbar-inverse navbar-fixed-top">
    <div class="container">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle collapsed