Question about dropdown and colors

if i have a dropdown with a list of color, how i can change a background color of a single textbox with a selected colour?

thanks

Unfortunately, that is not possible.

You can only change the background color of the dropdown options, please see this demo form: https://form.jotform.com/210471670247957, but you cannot change the background color of another field based on the selected color in the dropdown field.