title: How can you use flask to make the text of your website blue?
body: <p>How can you use flask to make the text of your website blue? I only know how to display text on your website. My code :</p>
  <pre><code>from flask import Flask
  
  app = Flask(__name__)
  
  @app.route('/')
  def hello_world():
      return '''Hello world'''
  </code></pre>