Change the color of button text

-- url of the page with the problem -- : provital-webdesign.de
-- HikaShop version -- : 3.0.1
-- Joomla version -- : 3.6.5
-- PHP version -- : 7.1

Hi,
I need your help again. I want to change the color of the button text, but I can't find the right css file.
Thanks
Wolf

I did not have enough coffee yet. Problem solved.
Thank you.