<?php header("Content-type: text/css; charset=utf-8"); 

$absolute_path = __FILE__;
$path_to_file = explode( 'wp-content', $absolute_path );
$path_to_wp = $path_to_file[0];

require_once( $path_to_wp . '/wp-load.php' );

$options_ibuki = get_option('ibuki'); 

echo $options_ibuki['custom-css'];

?>