How to change font colour for navigation text on a single page?

Site URL: https://www.cornwalladmin.com/about-us

Hi, 

How can I change the colour of the font of the navigation bar on a single page? I've attached an image of the code that I've tried but it's not working.

Thanks

Hi.

The site is private. Can you setup password & share url again?

You can also edit About Us Page >> Add a Code Block above text in screenshot >> Paste this code

<style>
  .header-nav-item a {
  	color: white !important;
  }
</style>