Conditional loading of builder-styles.css

function tf_start_buffer() {
	ob_start();
}
add_action( 'wp_head', 'tf_start_buffer', 1 );

function tf_end_buffer() {
	$output = ob_get_clean();
	if( preg_match( '/class=\"themify_builder_row/', $output ) ) {
		$output = str_replace(
			'<meta name="builder-styles-css" content="" id="builder-styles-css">',
			'<link rel="stylesheet" id="builder-styles-css" href="'. THEMIFY_BUILDER_URI . '/css/themify-builder-style.css' .'" media="all" />',
			$output
		);
	}
	echo $output;
}
add_action( 'wp_footer', 'tf_end_buffer', 10000 );