How to Display Frontend CSS for Administrator only

You should be able to simply check the capabilities of the currently logged in user. If they’re an administrator the following example should do what you want it to. Just add this into your theme’s functions.php file.

Please note this code is untested, but it should get you where you want to be. If the level_10 capability doesn’t work you can check out the documentation for other user levels and capabilities here.

add_action( 'wp_enqueue_scripts', 'admin_only_stylesheet' );

function admin_only_stylesheet() {

    if ( current_user_can('level_10') {

        wp_register_style( 'admin-only-style', get_template_directory_uri() . '/css/admin-frontend-style.css', array(), '12345678', 'all' );

        wp_enqueue_style( 'admin-only-style' );

    }

}