How can I recreate the folder layout from Telegram in SwiftUI? - layout

Question

I would like to recreate this layout, which is the layout of the Chat section from the Telegram app. The only thing I don't need to add is the horizontal scrolling. This is what I was able to recreate for now, but there's still too much space between the navigation bar and the folders list. How do I reduce it to be as small as the one in the Telegram app?
Here's my code:
import SwiftUI
struct ContentView: View {
#State var showMainView = true
#State var showFirstView = false
#State var showSecondView = false
var allItems = ["Italy", "Germany", "France", "Ireland", "Austria", "Sweden", "Norway", "Russia", "Ukraine", "Spain", "Portugal"]
var body: some View {
NavigationView {
VStack {
topMenu
Form {
if showMainView {
ForEach(allItems, id: \.self) { itms in
Text(itms)
}
}
if showFirstView {
ForEach(allItems.filter({ $0.first == "F" || $0.first == "G" }), id: \.self) { itms in
Text(itms)
}
}
if showSecondView {
Text("This folder is still empty!")
}
}
}
.toolbar {
ToolbarItem(placement: .principal) {
HStack {
Text("My List")
Spacer()
}
.padding(.leading)
}
}
.navigationBarItems(trailing: showMainView == true ? editButton : nil)
}
}
var topMenu : some View {
HStack(spacing: 15) {
Button {
showMainView = true
showFirstView = false
showSecondView = false
} label: {
if showMainView {
Text("All")
.underline()
} else {
Text("All")
}
}
.buttonStyle(BorderlessButtonStyle())
.foregroundColor(showMainView == true ? .green : .black)
Button {
showMainView = false
showFirstView = true
showSecondView = false
} label: {
if showFirstView {
Text("Folder 1")
.underline()
} else {
Text("Folder 1")
}
}
.buttonStyle(BorderlessButtonStyle())
.foregroundColor(showFirstView == true ? .green : .black)
Button {
showMainView = false
showFirstView = false
showSecondView = true
} label: {
if showSecondView {
Text("Folder 2")
.underline()
} else {
Text("Folder 2")
}
}
.buttonStyle(BorderlessButtonStyle())
.foregroundColor(showSecondView == true ? .green : .black)
Spacer()
}
.padding(.leading)
}
var editButton : some View {
Button {
} label: {
Text("Edit")
.foregroundColor(.green)
}
}
}
Thanks!