Navigation Bar: Change underline when hovering over Primary Item?

Using GeneratePress and Dispatch theme. I'd like to change the color of the underline/bar when hovering over a primary menu item from black to white.

Hover Bar Black

I've reviewed these links and although I can change the color to white, there's still a component of the bar that is black, possibly due to the bottom-to-up slide animation?
https://docs.generatepress.com/article/adding-menu-hover-animation/
https://generatepress.com/forums/topic/change-text-color-and-hover-color-in-nav-bar/
https://generatepress.com/forums/topic/menu-bar-color-change/

Thanks!