code: def css(self):
          
          css_list = [DEFAULT_MARK_CSS]
          for aes in self.aesthetics:
              css_list.extend(get_mark_css(aes, self.values[aes]))
          #print('\n'.join(css_list))
          return '\n'.join(css_list)
docs: Returns
          -------
          str
              The CSS.