// register main stylesheet
$file = '/library/css/style.css';
$lastmod = filemtime( get_stylesheet_directory() . $file );
wp_register_style( 'main-theme-style', get_stylesheet_directory_uri() . $file, array(), $lastmod, 'all' );

$file = '/library/js/scripts.js';
$lastmod = filemtime( get_stylesheet_directory() . $file );
wp_register_script( 'main-theme-js', get_stylesheet_directory_uri() . $file, array( 'jquery' ), $lastmod, true );