def get_theme(self):
        """
        Gets theme settings from settings service. Falls back to default (LMS) theme
        if settings service is not available, xblock theme settings are not set or does
        contain mentoring theme settings.
        """
        xblock_settings = self.get_xblock_settings(default={})
        if xblock_settings and self.theme_key in xblock_settings:
            return xblock_settings[self.theme_key]
        return self.default_theme_config