html_core_page = """
    <!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">
        <link rel="stylesheet" href="https://yastatic.net/bootstrap/3.3.1/css/bootstrap.min.css">
        <title>$title viewer</title>
        <style type="text/css" media="all">
            body { padding-top: 70px; padding-bottom: 40px }
            .scrollable-menu {
                height: auto;
                max-height: 400px;
                overflow-x: hidden;
            }
        </style>
    </head>
    <body>
        <nav class="navbar navbar-default navbar-fixed-top" style="box-shadow: 0px 0px 2px 1px rgba(0, 0, 0, 0.1);">
            <div class="container-fluid">
                <ul class="nav navbar-nav">
                    <p class="navbar-btn">
                        <div class="btn-group">
                            <button type="button" class="btn btn-primary">$title</button>
                            <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown" aria-expanded="false">
                                <span class="caret"></span>
                                <span class="sr-only">Toggle Dropdown</span>
                            </button>
                            <ul class="dropdown-menu" role="menu">
                                $viewers
                            </ul>
                        </div>
                    </p>
                </ul>
                $nav
            </div>
        </nav>
        $body
        <script src="https://yastatic.net/jquery/2.1.3/jquery.min.js"></script>
        <script src="https://yastatic.net/bootstrap/3.3.1/js/bootstrap.min.js"></script>
    </body>
    </html>
"""
