code: def css(self, *props, **kwprops):
          
          self._stable = False
          styles = {}
          if props:
              if len(props) == 1 and isinstance(props[0], Mapping):
                  styles = props[0]
              else:
                  raise WrongContentError(self, props, "Arguments not valid")
          elif kwprops:
              styles = kwprops
          else:
              raise WrongContentError(self, None, "args OR wkargs are needed")
          return self.attr(style=styles)
docs: Adds css properties to this element.