How do I change the color (back ground and text) of a specific sidebox?

I would like to change the information box to black with white writing...

Do I edit this code in the english.php???

// information box text in sideboxes/information.php
define('BOX_HEADING_INFORMATION', 'Information');
define('BOX_INFORMATION_PRIVACY', 'Privacy Notice');
define('BOX_INFORMATION_CONDITIONS', 'Conditions of Use');
define('BOX_INFORMATION_SHIPPING', 'Shipping & Returns');
define('BOX_INFORMATION_CONTACT', 'Contact Us');
define('BOX_BBINDEX', 'Forum');
define('BOX_INFORMATION_UNSUBSCRIBE', 'Newsletter Unsubscribe');

define('BOX_INFORMATION_SITE_MAP', 'Site Map');

OR do I do it in the css stylesheet???

Thanks.