<!DOCTYPE html>
<html lang="en">
  <head>
  {% block head %}
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>{{ page_title }}</title>

    <!-- Bootstrap -->
    <link href="{{ bootstrap_path }}/css/bootstrap.min.css" rel="stylesheet">

    <!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->
    <!-- WARNING: Respond.js doesn't work if you view the page via file:// -->
    <!--[if lt IE 9]>
      <script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
      <script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/respond.min.js"></script>
    <![endif]-->
  {% endblock %}
  </head>
  <body>
    <!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
    <!-- Include all compiled plugins (below), or include individual files as needed -->
    <script src="{{ bootstrap_path }}/js/bootstrap.min.js"></script>

    {% block body %}
    Hello World!
    {% endblock %}
  </body>
</html>

<!DOCTYPE html>
<html lang="en">
  <head>
  {% block head %}
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>{{ page_title }}</title>

    <!-- Bootstrap -->
    <link href="{{ bootstrap_path }}/css/bootstrap.min.css" rel="stylesheet">

    <!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->
    <!-- WARNING: Respond.js doesn't work if you view the page via file:// -->
    <!--[if lt IE 9]>
      <script src="https://oss.maxcdn.com/libs/html5shiv/3.7.0/html5shiv.js"></script>
      <script src="https://oss.maxcdn.com/libs/respond.js/1.4.2/respond.min.js"></script>
    <![endif]-->
  {% endblock %}
  {% block includes %}
  {% endblock %}
  </head>
  <body>
    <div class="container">
      {% block body %}
      Hello World!
      {% endblock %}
    </div>

    <!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
    <!-- Include all compiled plugins (below), or include individual files as needed -->
    <script src="{{ bootstrap_path }}/js/bootstrap.min.js"></script>

  </body>
</html>

Put main contaent in bootstrap container.
Put main contaent in bootstrap container.
