SwiftUI - how to keep Button on top?

I have the following SwiftUI view:

struct Flashcard : View {
@State var cardText = newArray[randomNum].kana


var body: some View {


  let stack = VStack{

  Text(cardText)
  .color(.red)
  .font(.title)
  .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: 200)


  .tapAction {
  self.flipCard()
  }

  HStack {
  Button(action: {
  print("button pressed")
  self.incorrect()
  }) {
  Image(systemName: "xmark.circle")
  .font(.title)
  }
  .opacity(0.4)


  Button(action: {
  print("button pressed")
  self.correct()
  }) {
  Image(systemName: "checkmark.circle")
  .font(.title)
  }
  .opacity(0.4)


  }
  }
  //.background(Color.blue)
  .cornerRadius(25)


  return stack
}

I'm trying to make the background colour of the VStack blue, but when I do that, I realise that the Buttons are no longer pressable. Is there a way to make them always on top? Should I be using a ZStack as well to make the Buttons the last view that is added to the stack? I tried using a ZStack but getting a lot of strange outcomes.