ios - How to get SwiftUI List and NavigationView with a background gradient?

Question

When I scroll a List, I want to shrink the navigation bar from large to small. This works by default, but if I try to add a gradient behind the table, it doesn't work any more. Code is attached (try uncommenting the Gradient to see). How do I get this to work?

import SwiftUI

struct BuyView: View {

    let numbers = ["1","2","4","1","2","4","1","2","4","1","2","4","1","2","4","1","2","4"]

    init() {
        UITableView.appearance().backgroundColor = .clear
        UITableViewCell.appearance().backgroundColor = .clear
    }

    var body: some View {
        NavigationView {
            ZStack {
//                LinearGradient(gradient: Gradient(colors: [.gray, .white]), startPoint: .top, endPoint: .bottom)
//                    .edgesIgnoringSafeArea(.all)
                List(numbers, id: \.self) { number in
                  Text(number)
                }.navigationBarTitle("Numbers")
            }
        }
    }
}

struct BuyView_Previews: PreviewProvider {
    static var previews: some View {
        BuyView()
    }
}