Hey i want to change the background color in this hex code #221F2B What is the color code for the plugin?

https://www.hexcolortool.com/#221F2B

It would be the rgba format I believe: 35 32 44 1

When i enter the color code the background change to white.

You should change it to "0.13 0.12 0.17 1.00" 

red:     0.13 = 35 / 255.
green: 0.12 = 32 / 255.
blue:    0.17 = 44 / 255.
alpha:  1 = 255 / 255.