struct ContentView: View {
   @Environment(ApplicationData.self) private var appData

   var body: some View {
      NavigationStack {
         List(appData.userData) { book in
            CellBook(book: book)
         }
         .navigationTitle(Text("Books"))
         .toolbarTitleDisplayMode(.inlineLarge)
         .toolbarBackgroundVisibility(.visible, for: .navigationBar)
         .toolbarBackground(.cyan, for: .navigationBar)
         .scrollEdgeEffectStyle(.hard, for: .top)
         .toolbar {
            ToolbarItem(placement: .topBarTrailing) {
               Button(action: {
                  print("Read Emails")
               }, label: {
                  Image(systemName: "envelope")
               })
            }
         }
      }
   }
}