wp_update_custom_css_post()

wp_update_custom_css_post() — Updates the custom_css post for a given theme. Inserts a custom_css post when one doesn’t yet exist.

Inputs: $css (string): CSS, stored in post_content. $args (array): Args. Field $preprocessed (string): Optional. Pre-processed CSS, stored in post_content_filtered. Normally empty string. Field $stylesheet (string): Optional. Stylesheet (child theme) to update. Defaults to active theme/stylesheet.

Returns WP_Post|WP_Error: Post on success, error on failure.