When I open SwiftKey keyboard the color of the navigation buttons changes (S8)

Hi there! Even though I´ve force-changed the background color on my navigation buttons in my Samsung S8 to be black, when I open the SwiftKey keyobard to enter text in any input, the background on my navbuttons changes to white. Is there any way to avoid this? It looks really ugly :(

Thanks! I love SwiftKey, keep up the good job! :)