Hi there,
Thanks for writing in.
I can’t find that article/post either but I think you’re looking a way to output the CSS into the file? If that’s the case, just use child theme’s style.css for your CSS and you’re good 
Then to make sure it’s more prioritized from other CSS, then please add this code to your child theme’s functions.php
function x_enqueue_site_styles() {
//
// Stack data.
//
$stack = x_get_stack();
$design = x_get_option( 'x_integrity_design' );
if ( $stack == 'integrity' && $design == 'light' ) {
$ext = '-light';
} elseif ( $stack == 'integrity' && $design == 'dark' ) {
$ext = '-dark';
} else {
$ext = '';
}
//
// Enqueue styles.
//
wp_enqueue_style( 'x-stack', X_TEMPLATE_URL . '/framework/css/dist/site/stacks/' . $stack . $ext . '.css', NULL, X_ASSET_REV, 'all' );
do_action( 'x_enqueue_styles' );
if ( is_rtl() ) {
wp_enqueue_style( 'x-rtl', X_TEMPLATE_URL . '/framework/css/dist/site/rtl/' . $stack . '.css', NULL, X_ASSET_REV, 'all' );
}
if ( X_BBPRESS_IS_ACTIVE ) {
if ( x_is_bbpress() ) {
wp_deregister_style( 'buttons' );
}
wp_deregister_style( 'bbp-default' );
wp_enqueue_style( 'x-bbpress', X_TEMPLATE_URL . '/framework/css/dist/site/bbpress/' . $stack . $ext . '.css', NULL, X_ASSET_REV, 'all' );
}
if ( X_BUDDYPRESS_IS_ACTIVE ) {
wp_deregister_style( 'bp-legacy-css' );
wp_deregister_style( 'bp-admin-bar' );
wp_enqueue_style( 'x-buddypress', X_TEMPLATE_URL . '/framework/css/dist/site/buddypress/' . $stack . $ext . '.css', NULL, X_ASSET_REV, 'all' );
}
if ( X_WOOCOMMERCE_IS_ACTIVE ) {
wp_deregister_style( 'woocommerce-layout' );
wp_deregister_style( 'woocommerce-general' );
wp_deregister_style( 'woocommerce-smallscreen' );
wp_enqueue_style( 'x-woocommerce', X_TEMPLATE_URL . '/framework/css/dist/site/woocommerce/' . $stack . $ext . '.css', NULL, X_ASSET_REV, 'all' );
}
if ( X_GRAVITY_FORMS_IS_ACTIVE ) {
wp_enqueue_style( 'x-gravity-forms', X_TEMPLATE_URL . '/framework/css/dist/site/gravity_forms/' . $stack . $ext . '.css', NULL, X_ASSET_REV, 'all' );
}
if ( X_CONTACT_FORM_7_IS_ACTIVE ) {
wp_deregister_style( 'contact-form-7' );
}
if ( is_child_theme() && apply_filters( 'x_enqueue_parent_stylesheet', false ) ) {
$rev = ( defined( 'X_CHILD_ASSET_REV' ) ) ? X_CHILD_ASSET_REV : X_ASSET_REV;
wp_enqueue_style( 'x-child', get_stylesheet_directory_uri() . '/style.css', array(), $rev, 'all' );
}
x_enqueue_google_fonts();
}
As for specific pages, you really need to add it in cornerstone’s custom CSS. Or, you can create your own style.css for each of your page, example, style-232.css where 232 is your page or post’s ID. Then simply add this code before x_enqueue_google_fonts(); from the above code.
if ( is_page ( 232 ) || is_single( 232 ) ) wp_enqueue_style( 'x-child-232', get_stylesheet_directory_uri() . '/style-232.css', array(), '1.0.0', 'all' );
Then add your CSS to style-232.css, and repeat each process if you wish to add more.
Please note that we can’t provide support for any customization, what I provided is the idea how it can be done 
Thanks!