Reply To: GeneratePress + Mantle Update (Save some code)

[Tom]

Adding CSS and functions can be done like this:
https://generatepress.com/knowledgebase/adding-css/
https://generatepress.com/knowledgebase/adding-php-functions/

Adding template files requires the child theme I’m afraid, so you wouldn’t be able to update.

However you could hook that extra content you’ve added into header.php into the generate_after_header_content hook: https://generatepress.com/knowledgebase/hook-list/