remove underline at additional images

Hallow everyone,
I'd like to remove underline at additional images, I guess I should edit css file and set {text-decoration:none;} but I can't find where is it.
Could anybody advice something.
I'm using Zen Cart 1.3.9g and installed Zen Lightbox and Image Handler 2 for v1.3.x.
http://glowkeyboard.com/glowing-fluorescent-english-us-keyboard-stickers-p-1.html

Thanks.

Looking with firefox I do not see an underline??

Thank you for reply, I just removed it.
I added style="text-decoration:none;" in tag <a> in the line

$script_link = '<script language="javascript" type="text/javascript"><!--' . "\n" . 'document.write(\'' . ($flag_display_large ? '<a style="text-decoration:none;" href="' . zen_lightbox($products_image_large, addslashes($products_name), LARGE_IMAGE_WIDTH, LARGE_IMAGE_HEIGHT) . '" rel="' . $rel . '" title="' . addslashes($products_name) . '">' . $thumb_slashes . '<br />' . TEXT_CLICK_TO_ENLARGE . '</a>' : $thumb_slashes) . '\');' . "\n" . '//--></script>';

includes/modules/MY_TEMPLATE/additional_images.php