def _get_by_id(self, style_id, style_type):
        """
        Return the style of *style_type* matching *style_id*. Returns the
        default for *style_type* if *style_id* is not found or if the style
        having *style_id* is not of *style_type*.
        """
        style = self._element.get_by_id(style_id)
        if style is None or style.type != style_type:
            return self.default(style_type)
        return StyleFactory(style)