micropat on "[Plugin: AddToAny Share Buttons] custom icon showed without white border"

I would like to remove the white border which surrounds my custom icon. You can refer to the image below

https://goo.gl/i6y867

https://wordpress.org/plugins/add-to-any/

See https://wordpress.org/support/topic/change-background-13

Place that line of CSS code to your "Additional CSS" box in AddToAny settings.