How to change site color on-the-fly?

[tony]

Hello,

I am new to PW and would like to achieve the following: when the user selects an item from a dropdown button, the site background color would change accordingly to the selected item. Can someone please give me a hint, or a minimal example? 

Regards, Tony

 

[dragan]

https://stackoverflow.com/a/36373890

[tony]

perfect answer, thank  you!