This is the standard, safe way to add stylesheets and scripts to your front-end.
/**
* Enqueue theme styles and scripts.
*/
function my_theme_enqueue_assets() {
// Load a CSS file
wp_enqueue_style( 'my-custom-style', get_stylesheet_directory_uri() . '/style.css', array(), '1.0.0' );
// Load a JS file
wp_enqueue_script( 'my-custom-script', get_stylesheet_directory_uri() . '/js/main.js', array('jquery'), '1.0.0', true );
}
add_action( 'wp_enqueue_scripts', 'my_theme_enqueue_assets' );
