Custom properties and the cascade
The cascade also applies to custom properties. We've set the value of --primary-color: to hsl(190, 95%, 51%);
as part of the :root rule set, and redefined it as hsl(280, 95%, 51%) it in the body rule set, which follows :root.
Use your browser's developer tools to toggle the --primary-color: hsl(10, 95%, 51%); rule on and off.