Button class not working

I'm trying to use the button class in a link i have in a custom module with light as the style in the sidebar module position but the link text isn't white in any of the states making it tough to read. is there a css override i can use here?

Hi,
Could you please provide me with a URL to your website, either here or via PM (click the “Private Message” text underneath my avatar) so that I may analyze it?