How to put the footer in gray

Hi!
How to put the footer in gray?
https://www.b2iconsulting.kessianeves.com
Thank you!

Hello there,

Thank you for contacting us.

Try adding this CSS code to Appearance > Customize > Additional CSS from dashboard.

    #colophon.site-footer {
      background-color: #4c4c4c;
    }     

Regards,
Kharis
aThemes Support