python - 我无法让 Flask-Bootstrap 正确呈现列

Question

我正在从 Bootstrap 站点复制/粘贴代码，即便如此，我也无法渲染任何内容。

代替：

列______________列__列

我得到：

列
列
列

__init__.py

from flask import Flask
from flask_bootstrap import Bootstrap

app = Flask(__name__)
bootstrap = Bootstrap(app)

from app import routes

base.html

{% extends "bootstrap/base.html" %}

    {% block content %}
        <div class="container">
            {% block app_content %}
            {% endblock %}
        </div>
    {% endblock %}

索引.html

{% extends "base.html" %}

{% block app_content %}

    <div class="container-fluid">
      <div class="row">
        <div class="col-md-2">
          One of three columns
        </div>
        <div class="col-md-8">
          One of three columns
        </div>
        <div class="col-md-2">
          One of three columns
        </div>
      </div>
    </div>


{% endblock %}