If anyone else is exploring System Colors, I've a simple web page that displays the CSS System Colors.

Unlike others, it displays them with both 'light' and 'dark' modes set. Uniquely it also displays the actual RGBA color displayed for the current browser/Operating system combination.

(The displayed colors are derived from the user's operating system's color scheme, so will vary based on your environment.)

Its a work in progress, but should be helpful to see them in action! Its available at https://github.com/eoconline/css-system-colors

Suggestions for enhancement are welcome!