old_contents: """
  A Sphinx extension adding a 'css' role creating links to
  the spec’s railroad diagrams.
  
  """
  
  from docutils import nodes
  
  
  def role_fn(_name, rawtext, text, lineno, inliner, options={}, content=()):
      ref = 'http://dev.w3.org/csswg/css-syntax-3/#%s-diagram' % text.replace(
          ' ', '-')
      if text.endswith(('-token', '-block')):
          text = '<%s>' % text
      ref = nodes.reference(rawtext, text, refuri=ref, **options)
      return [ref], []
  
  
  def setup(app):
      app.add_role_to_domain('py', 'diagram', role_fn)
  
new_contents: """
  A Sphinx extension adding a 'css' role creating links to
  the spec’s railroad diagrams.
  
  """
  
  from docutils import nodes
  
  
  def role_fn(_name, rawtext, text, lineno, inliner, options={}, content=()):
      ref = 'https://www.w3.org/TR/css-syntax-3/#%s-diagram' % text.replace(
          ' ', '-')
      if text.endswith(('-token', '-block')):
          text = '<%s>' % text
      ref = nodes.reference(rawtext, text, refuri=ref, **options)
      return [ref], []
  
  
  def setup(app):
      app.add_role_to_domain('py', 'diagram', role_fn)
  
subject: Change URL used for CSS diagrams