wp_custom_css_cb()

function wp_custom_css_cb() {
	$styles = wp_get_custom_css();
	if ( $styles || is_customize_preview() ) : ?>
		<style type="text/css" id="wp-custom-css">
			<?php echo strip_tags( $styles ); // Note that esc_html() cannot be used because `div &gt; span` is not interpreted properly. ?>
		</style>
	<?php endif;
}