Change CSS root variable dynamically using JavaScript

This example demonstrates how to change the background color of the page using CSS variables and JavaScript.
The initial background color is set to white using a CSS variable declared in the `:root` selector. The buttons below allow you to switch the background color to dark or light themes by updating the CSS variable dynamically using JavaScript.
This demonstrates that it is possible to override a CSS variable defined in the `:root` selector using inline styles in JavaScript.

Click the button to change the background color.