The color of the nav background changes to blue when the popup opens by default the background of the nav is set to green.
Here is my public share link: Webflow - Sunday Swing Golf Performance
Couldn’t recreate this behavior, I think by “popup” you meant the modal which is triggered by “Become a Member/Coach” in your nav?
Yes, Thanks for the help @shawncarrie I have fixed the issue. It was related to mobile breakpoint interaction.