How to Change Font Colour?

Need your kind to help, some of our articles for the font color are gray, is there method to make by default that can change the colors of all fonts in articles that have been published.
Please find below for example:
https://jualayamhias.com/ciri-ciri-ayam-pelung-khas-cianjur/

The page I need help with: [log in to see the link]