//include jquery-ui css
function custom_css() {
	wp_register_style( 'jquery-ui-custom-css', get_template_directory_uri() . '/js/jquery-ui-1.8.16.custom/css/ui-lightness/jquery-ui.1.8.16.custom.css' );

	wp_enqueue_style( 'jquery-ui-custom-css' );
}
add_action( 'wp_enqueue_scripts', 'custom_css' );