Color of the text within the text fields

How can I change the colour of the text within the text fields for the Contact Form 7 pluugin from white to black? At the moment the text is displaying white on white. Here is a link to the page that gives me trouble: https://www.luxlight.co.nz/?page_id=363

Thanks in advance for your help!

PS. I know good basic HTML but am a PHP noob.