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

   var body: some View {
      NavigationStack {
         VStack(spacing: 0) {
            HStack {
               Text("Books")
                  .font(.largeTitle.bold())
               Spacer()
               Button(action: {
                  print("Read Emails")
               }, label: {
                  Image(systemName: "envelope")
               }).buttonStyle(.glass)
            }.padding()
            .background(.cyan)

            List(appData.userData) { book in
               CellBook(book: book)
            }
         }
         .toolbarVisibility(.hidden, for: .navigationBar)         
      }
   }
}