SectionHeaders

import SwiftUI

struct ContentView: View {
    var body: some View {
        NavigationView {
            SidebarView()
            SidebarView()
        }
    }
}

struct SidebarView: View {
    var body: some View {
        ThemedList {
            ThemedSection("Header") {
                Text("Row")
                Text("Row")
                Text("Row")
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

struct ThemedList<Content>: View where Content: View {
    
    @ViewBuilder var content: () -> Content
    
    var body: some View {
        List {
            content()
                .listRowBackground(Color.red)
        }
    }
}

struct ThemedSection<Header, Content, Footer> {
    @ViewBuilder var header: () -> Header
    @ViewBuilder var footer: () -> Footer
    @ViewBuilder var content: () -> Content
}
extension ThemedSection : View where Header : View, Content : View, Footer : View {
    
    var body: some View {
        Section {
            content()
        } header: {
            header()
                .listRowBackground(Color.clear)
        } footer: {
            footer()
                .listRowBackground(Color.clear)
        }
    }
}
extension ThemedSection where Header == Text, Content : View, Footer == EmptyView {
    
    init<S>(_ title: S, @ViewBuilder content: @escaping () -> Content) where S : StringProtocol {
        
        self.content = content
        self.header = { Text(title) }
        self.footer = { EmptyView() }
    }
}