I need to change the color of the font in Contact Form 7

Hi I found that the color of my font changed from white to black in the message section of my contact form 7 when I upgraded to 4.3. I would like to change it back to white as the contrast is very difficult to see. I am in the Appearance>Custom CSS portion of my WP admin panel…can anyone give me some idea of what the code is and where I would insert it? Thanks so much!
PS here is a link to what I am talking about (see message section) https://warpdrivetutors.com/contact/