Ugly shadows on button, Blendmode not working - swift

Question

I want to implement a SwiftUI neomorphic button in SwiftUI but the shadows are messed up. To fix it, I use blendmode(overlay), but it has no effect on the button in NavBar. It works fine on the button in the regular view. The problem
Here’s my code
struct ContentView: View {
var body: some View {
NavigationView{
Button("Hi") { }
.foregroundColor(Color.primary)
.padding()
.background(
ZStack {
RoundedRectangle(cornerRadius: 12, style: .continuous)
.shadow(
color: .white,
radius: 12,
x: -6,
y: -8
)
.shadow(
color: Color.black.opacity(0.8),
radius: 12,
x: 6,
y: 8
)
.blendMode(.overlay)
.padding(2)
RoundedRectangle(cornerRadius: 12, style: .continuous)
.foregroundColor(color)
}
)
.navigationBarColor(UIbackground)
.navigationBarTitle("SwiftUI")
.frame(minWidth: 0, maxWidth: .infinity,
minHeight: 0, maxHeight: .infinity,
alignment: .center)
.background(color)
.navigationBarItems(leading: Button("Hi") { }
.foregroundColor(Color.primary)
.padding()
.background(
ZStack {
RoundedRectangle(cornerRadius: 12, style: .continuous)
.shadow(
color: .white,
radius: 12,
x: -6,
y: -8
)
.shadow(
color: Color.black.opacity(0.8),
radius: 12,
x: 6,
y: 8
)
.blendMode(.overlay)
.padding(2)
RoundedRectangle(cornerRadius: 12, style: .continuous)
.foregroundColor(color)
}
))
}
}
}
Any help would be appreciated.