ios: pin Sybil navigation theme

ios/Packages/Sybil/Sources/Sybil/SplitView.swift

@@ -4,8 +4,9 @@ public struct SplitView: View {
     @State private var viewModel = SybilViewModel()
     @Environment(\.horizontalSizeClass) private var horizontalSizeClass
 
-    public init() {
+    @MainActor public init() {
         SybilFontRegistry.registerIfNeeded()
+        SybilTheme.applySystemAppearance()
     }
 
     public var body: some View {
@@ -33,6 +34,7 @@ public struct SplitView: View {
             }
         }
         .font(.sybil(.body))
+        .preferredColorScheme(.dark)
         .task {
             await viewModel.bootstrap()
         }

ios/Packages/Sybil/Sources/Sybil/SybilMarkdownTheme.swift

@@ -10,6 +10,7 @@ extension Theme {
             .text {
                 FontFamily(.custom("Inter"))
                 FontSize(15)
+                ForegroundColor(SybilTheme.text)
             }
             .code {
                 FontFamilyVariant(.monospaced)

ios/Packages/Sybil/Sources/Sybil/SybilPhoneShellView.swift

@@ -30,8 +30,8 @@ struct SybilPhoneShellView: View {
                 .navigationTitle("")
                 .navigationBarTitleDisplayMode(.inline)
                 .toolbar {
-                    ToolbarItem(placement: .principal) {
+                    ToolbarItem(placement: .topBarLeading) {
-                        SybilWordmark(size: 19)
+                        SybilWordmark(size: 18)
                     }
                 }
                 .navigationDestination(for: PhoneRoute.self) { route in

ios/Packages/Sybil/Sources/Sybil/SybilSidebarView.swift

@@ -18,8 +18,6 @@ struct SybilSidebarView: View {
     var body: some View {
         VStack(spacing: 0) {
             VStack(alignment: .leading, spacing: 14) {
-                SybilWordmark(size: 31)
-
                 VStack(spacing: 10) {
                     sidebarActionButton(
                         title: "New chat",
@@ -174,6 +172,13 @@ struct SybilSidebarView: View {
             .padding(10)
         }
         .background(SybilTheme.panelGradient)
+        .navigationTitle("")
+        .navigationBarTitleDisplayMode(.inline)
+        .toolbar {
+            ToolbarItem(placement: .topBarLeading) {
+                SybilWordmark(size: 18)
+            }
+        }
     }
 
     private func sidebarActionButton(

ios/Packages/Sybil/Sources/Sybil/SybilTheme.swift

@@ -1,6 +1,7 @@
 import CoreText
 import Foundation
 import SwiftUI
+import UIKit
 
 enum SybilFontRegistry {
     static func registerIfNeeded() {
@@ -78,6 +79,23 @@ enum SybilTheme {
     static let userBubble = Color(red: 0.29, green: 0.13, blue: 0.65)
     static let danger = Color(red: 0.96, green: 0.32, blue: 0.40)
 
+    @MainActor static func applySystemAppearance() {
+        let navAppearance = UINavigationBarAppearance()
+        navAppearance.configureWithOpaqueBackground()
+        navAppearance.backgroundColor = UIColor(red: 0.02, green: 0.02, blue: 0.05, alpha: 1)
+        navAppearance.shadowColor = UIColor(red: 0.24, green: 0.20, blue: 0.38, alpha: 0.9)
+        navAppearance.titleTextAttributes = [
+            .foregroundColor: UIColor(red: 0.96, green: 0.94, blue: 1.0, alpha: 1)
+        ]
+        navAppearance.largeTitleTextAttributes = navAppearance.titleTextAttributes
+
+        UINavigationBar.appearance().prefersLargeTitles = false
+        UINavigationBar.appearance().standardAppearance = navAppearance
+        UINavigationBar.appearance().compactAppearance = navAppearance
+        UINavigationBar.appearance().scrollEdgeAppearance = navAppearance
+        UINavigationBar.appearance().compactScrollEdgeAppearance = navAppearance
+    }
+
     static var backgroundGradient: LinearGradient {
         LinearGradient(
             colors: [