Hide list separator/divider in NavigationStack

I have a problem with the sticky header in my view, when I scroll up I don't want that separator line on the video to be.

Just want to remove this separator, all list modifiers are not working for me.

My View code:

import SwiftUI

struct CalendarView: View {
    
    let dayLetters = ["S", "M", "T", "W", "T", "F", "S"]
    
    var body: some View {
        NavigationStack {
            List {
                Section {
                    RootView()
                } header: {
                    HStack {
                        ForEach(0..<dayLetters.count, id: \.self) { index in
                            Text(dayLetters[index])
                                .frame(maxWidth: .infinity)
                                .foregroundColor(.white)
                        }
                    }
                }
                .listRowInsets(EdgeInsets())
                .listRowSeparator(.hidden)
            }
            .navigationTitle("Calendar")
            .listStyle(.plain)
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    Button("Today") {
                        
                    }
                }
                ToolbarItem(placement: .navigationBarTrailing) {
                    Label("Transform Calendar", systemImage: "ellipsis")
                        .foregroundColor(.accentColor)
                }
                ToolbarItem(placement: .navigationBarTrailing) {
                    Button {
                        
                    } label: {
                        Label("Add", systemImage: "plus")
                    }
                }
            }
        }
    }
}

Do you have to be using List here? Try replacing List with a VStack. If you need scrolling, consider using a LazyVStack nested within a ScrollView.