old_contents: from flask import Blueprint, render_template, send_from_directory
  from splice.environment import Environment
  
  root = Blueprint('root', __name__)
  env = Environment.instance()
  
  campaign_static_path = env.application.config['STATIC_DIR'] + '/build/campaign-manager'
  
  
  @root.route('/', methods=['GET'])
  def index():
      return render_template('index.jinja2')
  
  
  @root.route('/distribution/', methods=['GET'])
  def distribution():
      return render_template('distribution.jinja2')
  
  
  @root.route('/campaign', methods=['GET'])
  def campaign():
      return send_from_directory(campaign_static_path, 'index.html')
  
  
  def register_routes(app):
      app.register_blueprint(root)
  
new_contents: from flask import Blueprint, render_template, send_from_directory
  from splice.environment import Environment
  import os
  
  root = Blueprint('root', __name__)
  env = Environment.instance()
  
  campaign_static_path = os.path.join(env.application.config['STATIC_DIR'], 'build/campaign-manager')
  
  
  @root.route('/', methods=['GET'])
  def index():
      return render_template('index.jinja2')
  
  
  @root.route('/distribution/', methods=['GET'])
  def distribution():
      return render_template('distribution.jinja2')
  
  
  @root.route('/campaign', methods=['GET'])
  def campaign():
      return send_from_directory(campaign_static_path, 'index.html')
  
  
  def register_routes(app):
      app.register_blueprint(root)
  
subject: use os.path.join