public static function register_styles( $path, $prefix = '', $version = null, $screen = 'all' ) {
		$function = function() use ( $path, $prefix, $version, $screen ) {
			foreach ( self::parse_dir( $path, 'css', $prefix ) as $handle => $data ) {
				if ( is_null( $version ) ) {
					$this_version = filemtime( $data['path'] );
				} else {
					$this_version = $version;
				}
				wp_register_style( $handle, $data['url'], $data['deps'], $this_version, $screen );
			}
		};
		if ( did_action( 'init' ) ) {
			$function();
		} else {
			add_action( 'init', $function );
		}
	}