flask extends two base.html

{% extends "layout.html" %}
{% block title %}Index{% endblock %}
{% block head %}
  {{ super() }}
  <style type="text/css">
    .important { color: #336699; }
  </style>
{% endblock %}
{% block content %}
  <h1>Index</h1>
  <p class="important">
    Welcome on my awesome homepage.
{% endblock %}

{% include "base_layout.html" %}
  <div>
  ... // write your code here
  </div>
{% block body %}{% endblock %}