wp-includes/theme.php:1961Renders the Custom CSS style element.
function wp_custom_css_cb() { $styles = wp_get_custom_css(); if ( ! $styles && ! is_customize_preview() ) { return; } $processor = new WP_HTML_Tag_Processor( '<style></style>' ); $processor->next_tag(); $processor->set_attribute( 'id', 'wp-custom-css' ); $processor->set_modifiable_text( "\n{$styles}\n" ); echo "{$processor->get_updated_html()}\n";}Introduced in 4.7.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/theme.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.