Properly queueing parent and child style.css, props Viper007Bond

parent-child-css.php

<?php

add_action( 'wp_enqueue_scripts', function() {
  wp_register_style( 'parent-theme', get_template_directory_uri() . '/style.css' );
  wp_enqueue_style( 'child-theme', get_stylesheet_uri(), array( 'parent-theme' ) );
} );