diff --git a/DasherApp/Sources/ContentView.swift b/DasherApp/Sources/ContentView.swift
index 40abbdc..a5276c4 100644
--- a/DasherApp/Sources/ContentView.swift
+++ b/DasherApp/Sources/ContentView.swift
@@ -11,6 +11,7 @@ struct ContentView: View {
     @State private var showOpenFile = false
     @State private var outputPaneFraction: CGFloat = 2.0 / 9.0
     @State private var showAlphabetPopover = false
+    @Environment(\.colorScheme) private var colorScheme
 
     var body: some View {
         GeometryReader { geometry in
@@ -67,6 +68,10 @@ struct ContentView: View {
                 .padding(.top, 8)
             }
         }
+        .onAppear { viewModel.bridge.setSystemAppearance(dark: colorScheme == .dark) }
+        .onChange(of: colorScheme) { _, newScheme in
+            viewModel.bridge.setSystemAppearance(dark: newScheme == .dark)
+        }
     }
 
     // MARK: - Layouts
diff --git a/DasherApp/Sources/DasherBridge.swift b/DasherApp/Sources/DasherBridge.swift
index ce768b2..850b517 100644
--- a/DasherApp/Sources/DasherBridge.swift
+++ b/DasherApp/Sources/DasherBridge.swift
@@ -350,6 +350,42 @@ class DasherBridge: InputMethodBridge {
         return String(cString: cStr)
     }
 
+
+    // MARK: - Appearance / dark mode (RFC 0007)
+
+    func setSystemAppearance(dark: Bool) {
+        guard let ctx = ctx else { return }
+        dasher_set_system_appearance(ctx, dark ? 2 : 1)
+    }
+    func setAppearanceMode(_ mode: Int) {
+        guard let ctx = ctx else { return }
+        dasher_set_appearance_mode(ctx, Int32(mode))
+    }
+    func getAppearanceMode() -> Int {
+        guard let ctx = ctx else { return 0 }
+        return Int(dasher_get_appearance_mode(ctx))
+    }
+    func setUserPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_user_palette(ctx, name)
+    }
+    func setLightPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_light_palette(ctx, name)
+    }
+    func setDarkPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_dark_palette(ctx, name)
+    }
+    func getLightPalette() -> String {
+        guard let ctx = ctx, let cStr = dasher_get_light_palette(ctx) else { return "" }
+        return String(cString: cStr)
+    }
+    func getDarkPalette() -> String {
+        guard let ctx = ctx, let cStr = dasher_get_dark_palette(ctx) else { return "" }
+        return String(cString: cStr)
+    }
+
     // MARK: - Alphabets
 
     var alphabetCount: Int {
diff --git a/DasherApp/Sources/DasherSettingsView.swift b/DasherApp/Sources/DasherSettingsView.swift
index 8a629c7..a4b48a5 100644
--- a/DasherApp/Sources/DasherSettingsView.swift
+++ b/DasherApp/Sources/DasherSettingsView.swift
@@ -169,41 +169,31 @@ struct DasherSettingsView: View {
 
     private func customizationSection(_ params: [DasherParameterInfo]) -> some View {
         Section {
+            Picker("Appearance", selection: Binding<Int>(
+                get: { viewModel.bridge.getAppearanceMode() },
+                set: { viewModel.bridge.setAppearanceMode($0) }
+            )) {
+                Text("System").tag(0)
+                Text("Light").tag(1)
+                Text("Dark").tag(2)
+            }
+            .pickerStyle(.segmented)
+
             let palettes = viewModel.bridge.allPalettes
             if !palettes.isEmpty {
-                VStack(alignment: .leading, spacing: 8) {
-                    Text("Colour Theme")
-                        .font(.subheadline)
-                    ScrollView(.horizontal, showsIndicators: false) {
-                        HStack(spacing: 10) {
-                            ForEach(0..<palettes.count, id: \.self) { i in
-                                let palette = palettes[i]
-                                let isSelected = viewModel.bridge.currentPalette == palette.name
-                                Button(action: { viewModel.bridge.setPalette(palette.name) }) {
-                                    VStack(spacing: 4) {
-                                        HStack(spacing: 2) {
-                                            ForEach(0..<min(palette.previewColors.count, 4), id: \.self) { ci in
-                                                RoundedRectangle(cornerRadius: 2)
-                                                    .fill(Color(cgColor: palette.previewColors[ci]))
-                                                    .frame(width: 16, height: 24)
-                                            }
-                                        }
-                                        .overlay(
-                                            RoundedRectangle(cornerRadius: 4)
-                                                .stroke(isSelected ? Color.accentColor : Color.gray.opacity(0.3), lineWidth: isSelected ? 2 : 1)
-                                        )
-                                        Text(palette.name)
-                                            .font(.system(size: 9))
-                                            .lineLimit(1)
-                                            .foregroundColor(isSelected ? .primary : .secondary)
-                                    }
-                                    .frame(width: 72)
-                                }
-                                .buttonStyle(.plain)
-                            }
-                        }
-                        .padding(.vertical, 2)
-                    }
+                palettePickerRow(
+                    label: "Light Palette",
+                    palettes: palettes,
+                    selectedName: viewModel.bridge.getLightPalette()
+                ) { name in
+                    viewModel.bridge.setLightPalette(name)
+                }
+                palettePickerRow(
+                    label: "Dark Palette",
+                    palettes: palettes,
+                    selectedName: viewModel.bridge.getDarkPalette()
+                ) { name in
+                    viewModel.bridge.setDarkPalette(name)
                 }
             }
             ForEach(params.filter { $0.name != "Color Palette" }) { param in
@@ -214,6 +204,49 @@ struct DasherSettingsView: View {
         }
     }
 
+    @ViewBuilder
+    private func palettePickerRow(
+        label: String,
+        palettes: [DasherPalette],
+        selectedName: String,
+        onSelect: @escaping (String) -> Void
+    ) -> some View {
+        VStack(alignment: .leading, spacing: 8) {
+            Text(label)
+                .font(.subheadline)
+            ScrollView(.horizontal, showsIndicators: false) {
+                HStack(spacing: 10) {
+                    ForEach(0..<palettes.count, id: \.self) { i in
+                        let palette = palettes[i]
+                        let isSelected = selectedName == palette.name
+                        Button(action: { onSelect(palette.name) }) {
+                            VStack(spacing: 4) {
+                                HStack(spacing: 2) {
+                                    ForEach(0..<min(palette.previewColors.count, 4), id: \.self) { ci in
+                                        RoundedRectangle(cornerRadius: 2)
+                                            .fill(Color(cgColor: palette.previewColors[ci]))
+                                            .frame(width: 16, height: 24)
+                                    }
+                                }
+                                .overlay(
+                                    RoundedRectangle(cornerRadius: 4)
+                                        .stroke(isSelected ? Color.accentColor : Color.gray.opacity(0.3), lineWidth: isSelected ? 2 : 1)
+                                )
+                                Text(palette.name)
+                                    .font(.system(size: 9))
+                                    .lineLimit(1)
+                                    .foregroundColor(isSelected ? .primary : .secondary)
+                            }
+                            .frame(width: 72)
+                        }
+                        .buttonStyle(.plain)
+                    }
+                }
+                .padding(.vertical, 2)
+            }
+        }
+    }
+
     // MARK: - Input
 
     private func inputSection(_ params: [DasherParameterInfo]) -> some View {
diff --git a/DasherCore b/DasherCore
index 581093e..5d6cfa0 160000
--- a/DasherCore
+++ b/DasherCore
@@ -1 +1 @@
-Subproject commit 581093ef2ed90456a0dbd70f5aba8d2950b075bd
+Subproject commit 5d6cfa0d4a65becda69af14eec9d679f42717456
diff --git a/DasherKeyboard/Sources/DasherBridge.swift b/DasherKeyboard/Sources/DasherBridge.swift
index f206060..02f389e 100644
--- a/DasherKeyboard/Sources/DasherBridge.swift
+++ b/DasherKeyboard/Sources/DasherBridge.swift
@@ -341,6 +341,42 @@ class DasherBridge: InputMethodBridge {
         return String(cString: cStr)
     }
 
+
+    // MARK: - Appearance / dark mode (RFC 0007)
+
+    func setSystemAppearance(dark: Bool) {
+        guard let ctx = ctx else { return }
+        dasher_set_system_appearance(ctx, dark ? 2 : 1)
+    }
+    func setAppearanceMode(_ mode: Int) {
+        guard let ctx = ctx else { return }
+        dasher_set_appearance_mode(ctx, Int32(mode))
+    }
+    func getAppearanceMode() -> Int {
+        guard let ctx = ctx else { return 0 }
+        return Int(dasher_get_appearance_mode(ctx))
+    }
+    func setUserPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_user_palette(ctx, name)
+    }
+    func setLightPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_light_palette(ctx, name)
+    }
+    func setDarkPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_dark_palette(ctx, name)
+    }
+    func getLightPalette() -> String {
+        guard let ctx = ctx, let cStr = dasher_get_light_palette(ctx) else { return "" }
+        return String(cString: cStr)
+    }
+    func getDarkPalette() -> String {
+        guard let ctx = ctx, let cStr = dasher_get_dark_palette(ctx) else { return "" }
+        return String(cString: cStr)
+    }
+
     // MARK: - Alphabets
 
     var alphabetCount: Int {
diff --git a/DasherKeyboard/Sources/KeyboardViewController.swift b/DasherKeyboard/Sources/KeyboardViewController.swift
index f0c1a36..95bfe9b 100644
--- a/DasherKeyboard/Sources/KeyboardViewController.swift
+++ b/DasherKeyboard/Sources/KeyboardViewController.swift
@@ -118,6 +118,7 @@ class KeyboardViewController: UIInputViewController {
     }
 
     @objc private func resetTapped() {
+        viewModel?.bridge.setSystemAppearance(dark: traitCollection.userInterfaceStyle == .dark)
         viewModel?.bridge.reset()
     }
 
@@ -133,10 +134,16 @@ class KeyboardViewController: UIInputViewController {
         super.viewWillAppear(animated)
         // The bridge is a singleton so its model state survives across open/close
         // cycles. Reset to the root so each keyboard session starts fresh.
+        viewModel?.bridge.setSystemAppearance(dark: traitCollection.userInterfaceStyle == .dark)
         viewModel?.bridge.reset()
         canvas?.requestRedraw()
     }
 
+    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
+        super.traitCollectionDidChange(previousTraitCollection)
+        viewModel?.bridge.setSystemAppearance(dark: traitCollection.userInterfaceStyle == .dark)
+    }
+
     override func viewDidLayoutSubviews() {
         super.viewDidLayoutSubviews()
         viewModel?.setCanvasSize(canvas?.bounds.size ?? view.bounds.size)
diff --git a/DasherMac/Sources/DasherBridge.swift b/DasherMac/Sources/DasherBridge.swift
index 64c914a..04a9712 100644
--- a/DasherMac/Sources/DasherBridge.swift
+++ b/DasherMac/Sources/DasherBridge.swift
@@ -353,6 +353,42 @@ class DasherBridge: InputMethodBridge, DasherBridgeProtocol {
         return String(cString: cStr)
     }
 
+
+    // MARK: - Appearance / dark mode (RFC 0007)
+
+    func setSystemAppearance(dark: Bool) {
+        guard let ctx = ctx else { return }
+        dasher_set_system_appearance(ctx, dark ? 2 : 1)
+    }
+    func setAppearanceMode(_ mode: Int) {
+        guard let ctx = ctx else { return }
+        dasher_set_appearance_mode(ctx, Int32(mode))
+    }
+    func getAppearanceMode() -> Int {
+        guard let ctx = ctx else { return 0 }
+        return Int(dasher_get_appearance_mode(ctx))
+    }
+    func setUserPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_user_palette(ctx, name)
+    }
+    func setLightPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_light_palette(ctx, name)
+    }
+    func setDarkPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_dark_palette(ctx, name)
+    }
+    func getLightPalette() -> String {
+        guard let ctx = ctx, let cStr = dasher_get_light_palette(ctx) else { return "" }
+        return String(cString: cStr)
+    }
+    func getDarkPalette() -> String {
+        guard let ctx = ctx, let cStr = dasher_get_dark_palette(ctx) else { return "" }
+        return String(cString: cStr)
+    }
+
     // MARK: - Alphabets
 
     var alphabetCount: Int {
diff --git a/DasherMac/Sources/MacContentView.swift b/DasherMac/Sources/MacContentView.swift
index 20633a0..7b7e027 100644
--- a/DasherMac/Sources/MacContentView.swift
+++ b/DasherMac/Sources/MacContentView.swift
@@ -8,6 +8,7 @@ struct MacContentView: View {
     @State private var showSettings = false
     @State private var currentLayoutPosition = "Right"
     @State private var outputPaneFraction: CGFloat = 2.0 / 9.0
+    @Environment(\.colorScheme) private var colorScheme
 
     var body: some View {
         VStack(spacing: 0) {
@@ -69,6 +70,10 @@ struct MacContentView: View {
                 }
             }
         }
+        .onAppear { viewModel.bridge.setSystemAppearance(dark: colorScheme == .dark) }
+        .onChange(of: colorScheme) { _, newScheme in
+            viewModel.bridge.setSystemAppearance(dark: newScheme == .dark)
+        }
     }
 
     private var layoutPickerMenu: some View {
diff --git a/DasherVision/Sources/DasherBridge.swift b/DasherVision/Sources/DasherBridge.swift
index 1fe7438..e0d72fd 100644
--- a/DasherVision/Sources/DasherBridge.swift
+++ b/DasherVision/Sources/DasherBridge.swift
@@ -315,6 +315,42 @@ class DasherBridge: InputMethodBridge {
         return String(cString: cStr)
     }
 
+
+    // MARK: - Appearance / dark mode (RFC 0007)
+
+    func setSystemAppearance(dark: Bool) {
+        guard let ctx = ctx else { return }
+        dasher_set_system_appearance(ctx, dark ? 2 : 1)
+    }
+    func setAppearanceMode(_ mode: Int) {
+        guard let ctx = ctx else { return }
+        dasher_set_appearance_mode(ctx, Int32(mode))
+    }
+    func getAppearanceMode() -> Int {
+        guard let ctx = ctx else { return 0 }
+        return Int(dasher_get_appearance_mode(ctx))
+    }
+    func setUserPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_user_palette(ctx, name)
+    }
+    func setLightPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_light_palette(ctx, name)
+    }
+    func setDarkPalette(_ name: String) {
+        guard let ctx = ctx else { return }
+        dasher_set_dark_palette(ctx, name)
+    }
+    func getLightPalette() -> String {
+        guard let ctx = ctx, let cStr = dasher_get_light_palette(ctx) else { return "" }
+        return String(cString: cStr)
+    }
+    func getDarkPalette() -> String {
+        guard let ctx = ctx, let cStr = dasher_get_dark_palette(ctx) else { return "" }
+        return String(cString: cStr)
+    }
+
     // MARK: - Alphabets
 
     var alphabetCount: Int {
diff --git a/DasherVision/Sources/VisionContentView.swift b/DasherVision/Sources/VisionContentView.swift
index 3ee94ea..0c43136 100644
--- a/DasherVision/Sources/VisionContentView.swift
+++ b/DasherVision/Sources/VisionContentView.swift
@@ -73,6 +73,7 @@ struct VisionContentView: View {
         .sheet(isPresented: $showSettings) {
             VisionSettingsView(viewModel: viewModel)
         }
+        .onAppear { viewModel.bridge.setSystemAppearance(dark: true) }
     }
 
     private func toolbarButton(_ icon: String, isAccent: Bool = false, _ action: @escaping () -> Void) -> some View {