protected function prepare_wrapper_classes() {

		$defaults = array();

		// Base field class.
		$defaults[] = 'llms-form-field';

		// Add class for the field type.
		$defaults[] = sprintf( 'type-%s', $this->settings['type'] );

		if ( $this->is_input_group() ) {
			$defaults[] = 'is-group';
		}

		// Add columns classes.
		$defaults[] = sprintf( 'llms-cols-%d', $this->settings['columns'] );
		if ( $this->settings['last_column'] ) {
			$defaults[] = 'llms-cols-last';
		}

		// If required, add a class.
		if ( $this->settings['required'] ) {
			$defaults[] = 'llms-is-required';
		}

		$this->settings['wrapper_classes'] = $this->classes_ensure_array(
			$this->settings['wrapper_classes'],
			$defaults
		);

	}