Drop down Menu background


In my design, I have a simple nav bar animation where the nav bar has a transparent background in its initial state but when scrolling it turns white and the text turns blue.
My problem is that I’d want the smaller viewpoints (phone, tablet) menu always to have a white background and not follow the same color change the nav bar does.

I know its probably a minor issue, but I’m having some trouble figuring it out:

Thank you !!!