Builder: Enqueue custom stylesheet (custom.css) in the child theme directory to keep custom CSS code separate from style.css -- custom.css overrides style.css

builder_custom_css_file.php

<?php

// Enqueue custom stylesheet in child theme directory
function intw_custom_styles() {
  wp_enqueue_style( 'custom-style', get_stylesheet_directory_uri() . '/custom.css', '1.0.0', 'all' );
}
add_action('wp_enqueue_scripts', 'intw_custom_styles');