diff --git a/Sky/ScriptMessageHandler.swift b/Sky/ScriptMessageHandler.swift
index 3416d02..2e6713f 100644
--- a/Sky/ScriptMessageHandler.swift
+++ b/Sky/ScriptMessageHandler.swift
@@ -50,12 +50,10 @@ class ScriptMessageHandler: NSObject, WKScriptMessageHandler {
                let darkMode = messageBody["darkMode"] as? Int,
                let backgroundColor = messageBody["backgroundColor"] as? String
             {
-                // NSLog("colorScheme: \(colorScheme), darkMode: \(darkMode), backgroundColor: \(backgroundColor)")
-                if darkMode == 1 {
-                    viewController.updateTitleBar(.dark, backgroundColor: backgroundColor)
-                } else {
-                    viewController.updateTitleBar(.light, backgroundColor: backgroundColor)
-                }
+                let colorMode = messageBody["colorMode"] as? String
+                // NSLog("colorScheme: \(colorScheme), darkMode: \(darkMode), backgroundColor: \(backgroundColor), colorMode: \(colorMode ?? "nil")")
+                let mode: ViewController.WindowColorScheme = darkMode == 1 ? .dark : .light
+                viewController.updateTitleBar(mode, backgroundColor: backgroundColor, colorMode: colorMode)
             }
         }
     }
diff --git a/Sky/Scripts/hook_window_color_scheme.js b/Sky/Scripts/hook_window_color_scheme.js
index ec61736..3a34807 100644
--- a/Sky/Scripts/hook_window_color_scheme.js
+++ b/Sky/Scripts/hook_window_color_scheme.js
@@ -88,6 +88,7 @@ function updateColorSchemeWithBskyStorage(bskyStorage) {
         colorScheme: match.name,
         darkMode: match.darkMode,
         backgroundColor: match.backgroundColor,
+        colorMode: colorMode,
     });
     return true;
 }
@@ -106,6 +107,7 @@ function updateColorSchemeAuto() {
         colorScheme: match.name,
         darkMode: match.darkMode,
         backgroundColor: match.backgroundColor,
+        colorMode: "system",
     });
     return true;
 }
diff --git a/Sky/ViewController.swift b/Sky/ViewController.swift
index 3fbe987..f474444 100644
--- a/Sky/ViewController.swift
+++ b/Sky/ViewController.swift
@@ -46,12 +46,12 @@ class ViewController: NSViewController {
         NSLog("checkAppearance initSystemAppearanceValue = \(initSystemAppearanceValue)")
         if self.webView != nil {
             NSLog("checkAppearance setting local storage")
-            self.webView.evaluateJavaScript(
-                Scripts.localStorageSetItem(
-                    key: LocalStorageKeys.initSystemAppearance,
-                    value: initSystemAppearanceValue
-                )
-            )
+            // Chain updateColorScheme() so the title bar message sees the fresh localStorage.
+            let script = Scripts.localStorageSetItem(
+                key: LocalStorageKeys.initSystemAppearance,
+                value: initSystemAppearanceValue
+            ) + "\nif (typeof updateColorScheme === 'function') { updateColorScheme(); }"
+            self.webView.evaluateJavaScript(script)
         }
     }
 
@@ -477,7 +477,7 @@ class ViewController: NSViewController {
         case light
     }
 
-    func updateTitleBar(_ mode: WindowColorScheme, backgroundColor: String) {
+    func updateTitleBar(_ mode: WindowColorScheme, backgroundColor: String, colorMode: String? = nil) {
         if backgroundColor.starts(with:"rgb("),
             let range = backgroundColor.range(of: #"\((.*?)\)"#, options: .regularExpression)
         {
@@ -496,7 +496,10 @@ class ViewController: NSViewController {
                 )
             }
         }
-        if mode == .dark {
+        // Leave appearance unset for "system" so WKWebView's prefers-color-scheme follows macOS.
+        if colorMode == "system" {
+            self.webView.window!.appearance = nil
+        } else if mode == .dark {
             self.webView.window!.appearance = NSAppearance(named: .darkAqua)
         } else {
             self.webView.window!.appearance = NSAppearance(named: .aqua)