diff --git a/desktopApp/src/main/kotlin/com/vnidrop/app/main.kt b/desktopApp/src/main/kotlin/com/vnidrop/app/main.kt
index 0921de6..fa8c564 100644
--- a/desktopApp/src/main/kotlin/com/vnidrop/app/main.kt
+++ b/desktopApp/src/main/kotlin/com/vnidrop/app/main.kt
@@ -1,6 +1,26 @@
 package com.vnidrop.app
 
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.text.BasicText
+import androidx.compose.foundation.window.WindowDraggableArea
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.ExperimentalComposeUiApi
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.awt.awtEventOrNull
+import androidx.compose.ui.input.pointer.PointerEventType
+import androidx.compose.ui.input.pointer.onPointerEvent
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.dp
+import androidx.compose.ui.unit.sp
 import androidx.compose.ui.window.Window
+import androidx.compose.ui.window.WindowScope
 import androidx.compose.ui.window.application
 import com.vnidrop.app.platform.DesktopAppearanceBridge
 import com.vnidrop.app.feature.send.DesktopShareBridge
@@ -8,11 +28,13 @@ import com.vnidrop.app.feature.receive.ExternalInvitationController
 import com.vnidrop.app.feature.receive.MaxVniDropInvitationBytes
 import com.vnidrop.app.feature.receive.VniDropInvitationExtension
 import com.vnidrop.app.feature.receive.decodeInvitationBytes
+import com.vnidrop.app.ui.theme.LocalVniDropColors
 import java.awt.Desktop
 import java.io.File
 
 fun main(args: Array<String>) {
 	val externalInvitations = ExternalInvitationController()
+	val macOs = DesktopAppearanceBridge.isMacOs()
 	configureMacOsNativeAppearance()
 	configureInvitationOpenHandler(externalInvitations)
 	args.asSequence()
@@ -20,7 +42,7 @@ fun main(args: Array<String>) {
 		.filter { it.extension.equals(VniDropInvitationExtension, ignoreCase = true) }
 		.forEach { externalInvitations.openFile(it) }
 	DesktopAppearanceBridge.applyNativeAppearance = MacOsAppKitAppearance::apply
-	if (System.getProperty("os.name").startsWith("Mac", ignoreCase = true)) {
+	if (macOs) {
 		DesktopShareBridge.shareFile = MacOsShareSheet::share
 	}
 	application {
@@ -28,7 +50,16 @@ fun main(args: Array<String>) {
 			onCloseRequest = ::exitApplication,
 			title = "vnidrop",
 		) {
-			App(rememberJvmAppDependencies(externalInvitations))
+			App(
+				dependencies = rememberJvmAppDependencies(externalInvitations),
+				windowChromeTopInset = if (macOs) MacOsTitleBarHeight else 0.dp,
+				windowContentTopStartRadius = if (macOs) MacOsContentCornerRadius else 0.dp,
+				windowChrome = if (macOs) {
+					{ MacOsTitleBar() }
+				} else {
+					null
+				},
+			)
 		}
 	}
 }
@@ -52,8 +83,47 @@ private fun ExternalInvitationController.openFile(file: File) {
 }
 
 private fun configureMacOsNativeAppearance() {
-	if (!System.getProperty("os.name").startsWith("Mac", ignoreCase = true)) return
+	if (!DesktopAppearanceBridge.isMacOs()) return
 	// AWT reads this before creating the first native window. Runtime theme
 	// changes are handled in the JVM platform appearance hook.
 	System.setProperty("apple.awt.application.appearance", "system")
 }
+
+private val MacOsTitleBarHeight = 28.dp
+private val MacOsTrafficLightsWidth = 76.dp
+private val MacOsContentCornerRadius = 20.dp
+
+@Composable
+@OptIn(ExperimentalComposeUiApi::class)
+private fun WindowScope.MacOsTitleBar() {
+	val colors = LocalVniDropColors.current
+	Box(
+		modifier = Modifier
+			.fillMaxWidth()
+			.height(MacOsTitleBarHeight)
+			.background(colors.backgroundSurface200),
+	) {
+		WindowDraggableArea(
+			modifier = Modifier
+				.fillMaxSize()
+				.padding(start = MacOsTrafficLightsWidth)
+				.onPointerEvent(PointerEventType.Press) { event ->
+					if (event.awtEventOrNull?.clickCount == 2) {
+						DesktopAppearanceBridge.toggleMaximized(window)
+					}
+				},
+		) {
+			Box(modifier = Modifier.fillMaxSize().padding(end = MacOsTrafficLightsWidth)) {
+				BasicText(
+					text = "vnidrop",
+					modifier = Modifier.align(Alignment.Center),
+					style = TextStyle(
+						color = colors.foregroundDefault,
+						fontSize = 13.sp,
+						fontWeight = FontWeight.SemiBold,
+					),
+				)
+			}
+		}
+	}
+}
diff --git a/shared/src/commonMain/kotlin/com/vnidrop/app/App.kt b/shared/src/commonMain/kotlin/com/vnidrop/app/App.kt
index 2db6bf5..f1c9198 100644
--- a/shared/src/commonMain/kotlin/com/vnidrop/app/App.kt
+++ b/shared/src/commonMain/kotlin/com/vnidrop/app/App.kt
@@ -1,5 +1,7 @@
 package com.vnidrop.app
 
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.BoxWithConstraints
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxSize
@@ -10,6 +12,7 @@ import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.Lifecycle
 import androidx.lifecycle.LifecycleEventObserver
@@ -36,6 +39,7 @@ import com.vnidrop.app.ui.shell.ScreenScrollContainer
 import com.vnidrop.app.core.TransferDirection
 import com.vnidrop.app.ui.state.WindowClass
 import com.vnidrop.app.ui.state.windowClassFor
+import com.vnidrop.app.ui.theme.LocalVniDropColors
 import com.vnidrop.app.ui.theme.VniDropTheme
 import com.vnidrop.app.ui.theme.rememberResolvedDarkTheme
 import kotlinx.coroutines.flow.filter
@@ -43,7 +47,12 @@ import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.withTimeoutOrNull
 
 @Composable
-fun App(dependencies: AppDependencies) {
+fun App(
+	dependencies: AppDependencies,
+	windowChromeTopInset: Dp = 0.dp,
+	windowContentTopStartRadius: Dp = 0.dp,
+	windowChrome: (@Composable () -> Unit)? = null,
+) {
 	val graphHolder = viewModel { AppGraphViewModel(dependencies) }
 	val graph = graphHolder.graph
 
@@ -122,55 +131,67 @@ fun App(dependencies: AppDependencies) {
 	val darkTheme = rememberResolvedDarkTheme(appState.themeMode)
 	PlatformSystemAppearance(darkTheme)
 	VniDropTheme(isDarkTheme = darkTheme) {
-		BoxWithConstraints {
-			val windowClass = windowClassFor(maxWidth.value)
-			val showSendAction = appState.destination == AppDestination.Send &&
-				windowClass == WindowClass.Phone &&
-				sendState.selectedTransferId?.let { selectedId ->
-					sendCoreState.transfers.any { it.transferId == selectedId }
-				} != true &&
-				sendCoreState.transfers.any { it.direction == TransferDirection.Send }
-			val showReceiveAction = appState.destination == AppDestination.Receive &&
-				windowClass == WindowClass.Phone &&
-				!receiveState.isAcquisitionOpen &&
-				receiveCoreState.transfers.any { it.direction == TransferDirection.Receive }
-			AppShell(
-				modifier = Modifier.fillMaxSize(),
-				selectedDestination = appState.destination,
-				windowClass = windowClass,
-				onDestinationSelected = appViewModel::selectDestination,
-				overlay = {
-					VniDropSnackbarHost(graph.messages, Modifier.align(Alignment.BottomCenter))
-				},
-				floatingAction = if (showSendAction) {
-					{
-						SendFloatingAction(
-							onClick = sendViewModel::openComposer,
-							modifier = Modifier.align(Alignment.BottomEnd).padding(16.dp),
-						)
-					}
-				} else if (showReceiveAction) {
-					{
-						ReceiveFloatingAction(
-							onClick = receiveViewModel::openAcquisition,
-							modifier = Modifier.align(Alignment.BottomEnd).padding(16.dp),
-						)
-					}
-				} else {
-					null
-				},
+		Box(
+			modifier = Modifier
+				.fillMaxSize()
+				.background(LocalVniDropColors.current.backgroundSurface200),
+		) {
+			BoxWithConstraints(
+				modifier = Modifier
+					.fillMaxSize()
+					.padding(top = windowChromeTopInset),
 			) {
-				when (appState.destination) {
-					AppDestination.Send -> SendRoute(sendViewModel, windowClass)
-					AppDestination.Receive -> ReceiveRoute(receiveViewModel, windowClass)
-					AppDestination.Settings -> ScreenScrollContainer { SettingsRoute(settingsViewModel, windowClass) }
+				val windowClass = windowClassFor(maxWidth.value)
+				val showSendAction = appState.destination == AppDestination.Send &&
+					windowClass == WindowClass.Phone &&
+					sendState.selectedTransferId?.let { selectedId ->
+						sendCoreState.transfers.any { it.transferId == selectedId }
+					} != true &&
+					sendCoreState.transfers.any { it.direction == TransferDirection.Send }
+				val showReceiveAction = appState.destination == AppDestination.Receive &&
+					windowClass == WindowClass.Phone &&
+					!receiveState.isAcquisitionOpen &&
+					receiveCoreState.transfers.any { it.direction == TransferDirection.Receive }
+				AppShell(
+					modifier = Modifier.fillMaxSize(),
+					selectedDestination = appState.destination,
+					windowClass = windowClass,
+					mainContentTopStartRadius = windowContentTopStartRadius,
+					onDestinationSelected = appViewModel::selectDestination,
+					overlay = {
+						VniDropSnackbarHost(graph.messages, Modifier.align(Alignment.BottomCenter))
+					},
+					floatingAction = if (showSendAction) {
+						{
+							SendFloatingAction(
+								onClick = sendViewModel::openComposer,
+								modifier = Modifier.align(Alignment.BottomEnd).padding(16.dp),
+							)
+						}
+					} else if (showReceiveAction) {
+						{
+							ReceiveFloatingAction(
+								onClick = receiveViewModel::openAcquisition,
+								modifier = Modifier.align(Alignment.BottomEnd).padding(16.dp),
+							)
+						}
+					} else {
+						null
+					},
+				) {
+					when (appState.destination) {
+						AppDestination.Send -> SendRoute(sendViewModel, windowClass)
+						AppDestination.Receive -> ReceiveRoute(receiveViewModel, windowClass)
+						AppDestination.Settings -> ScreenScrollContainer { SettingsRoute(settingsViewModel, windowClass) }
+					}
 				}
+				ApprovalModalHost(
+					state = approvalState,
+					onAccept = graph.approvalCoordinator::accept,
+					onRefuse = graph.approvalCoordinator::refuse,
+				)
 			}
-			ApprovalModalHost(
-				state = approvalState,
-				onAccept = graph.approvalCoordinator::accept,
-				onRefuse = graph.approvalCoordinator::refuse,
-			)
+			windowChrome?.invoke()
 		}
 	}
 }
diff --git a/shared/src/commonMain/kotlin/com/vnidrop/app/ui/navigation/AppNavigation.kt b/shared/src/commonMain/kotlin/com/vnidrop/app/ui/navigation/AppNavigation.kt
index e18df13..8815212 100644
--- a/shared/src/commonMain/kotlin/com/vnidrop/app/ui/navigation/AppNavigation.kt
+++ b/shared/src/commonMain/kotlin/com/vnidrop/app/ui/navigation/AppNavigation.kt
@@ -28,6 +28,7 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import com.vnidrop.app.ui.theme.LocalVniDropColors
 import org.jetbrains.compose.resources.stringResource
@@ -36,6 +37,7 @@ import org.jetbrains.compose.resources.stringResource
 fun AppSidebarNavigation(
 	selected: AppDestination,
 	onDestinationSelected: (AppDestination) -> Unit,
+	dividerTopInset: Dp = 0.dp,
 	modifier: Modifier = Modifier,
 ) {
 	val colors = LocalVniDropColors.current
@@ -62,7 +64,8 @@ fun AppSidebarNavigation(
 		}
 		Box(
 			modifier = Modifier
-				.align(Alignment.CenterEnd)
+				.align(Alignment.TopEnd)
+				.padding(top = dividerTopInset)
 				.width(1.dp)
 				.fillMaxHeight()
 				.background(colors.borderDefault),
diff --git a/shared/src/commonMain/kotlin/com/vnidrop/app/ui/shell/AppShell.kt b/shared/src/commonMain/kotlin/com/vnidrop/app/ui/shell/AppShell.kt
index 8cd455e..d149b62 100644
--- a/shared/src/commonMain/kotlin/com/vnidrop/app/ui/shell/AppShell.kt
+++ b/shared/src/commonMain/kotlin/com/vnidrop/app/ui/shell/AppShell.kt
@@ -10,9 +10,12 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.statusBarsPadding
 import androidx.compose.foundation.lazy.LazyColumn
+import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.Surface
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.clip
+import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
 import com.vnidrop.app.ui.navigation.AppBottomNavigation
 import com.vnidrop.app.ui.navigation.AppDestination
@@ -26,6 +29,7 @@ fun AppShell(
 	modifier: Modifier = Modifier,
 	selectedDestination: AppDestination,
 	windowClass: WindowClass,
+	mainContentTopStartRadius: Dp = 0.dp,
 	onDestinationSelected: (AppDestination) -> Unit,
 	overlay: @Composable BoxScope.() -> Unit = {},
 	floatingAction: (@Composable BoxScope.() -> Unit)? = null,
@@ -49,6 +53,7 @@ fun AppShell(
 		} else {
 			WideShell(
 				selectedDestination = selectedDestination,
+				mainContentTopStartRadius = mainContentTopStartRadius,
 				onDestinationSelected = onDestinationSelected,
 				overlay = overlay,
 				floatingAction = floatingAction,
@@ -61,17 +66,38 @@ fun AppShell(
 @Composable
 private fun WideShell(
 	selectedDestination: AppDestination,
+	mainContentTopStartRadius: Dp,
 	onDestinationSelected: (AppDestination) -> Unit,
 	overlay: @Composable BoxScope.() -> Unit,
 	floatingAction: (@Composable BoxScope.() -> Unit)?,
 	content: @Composable () -> Unit,
 ) {
-	Row(modifier = Modifier.fillMaxSize()) {
+	val colors = LocalVniDropColors.current
+	val roundedContent = mainContentTopStartRadius > 0.dp
+	Row(
+		modifier = Modifier
+			.fillMaxSize()
+			.then(if (roundedContent) Modifier.background(colors.backgroundSurface200) else Modifier),
+	) {
 		AppSidebarNavigation(
 			selected = selectedDestination,
+			dividerTopInset = mainContentTopStartRadius,
 			onDestinationSelected = onDestinationSelected,
 		)
-		Box(modifier = Modifier.weight(1f).fillMaxSize()) {
+		Box(
+			modifier = Modifier
+				.weight(1f)
+				.fillMaxSize()
+				.then(
+					if (roundedContent) {
+						Modifier
+							.clip(RoundedCornerShape(topStart = mainContentTopStartRadius))
+							.background(colors.backgroundDashCanvas)
+					} else {
+						Modifier
+					},
+				),
+		) {
 			content()
 			floatingAction?.invoke(this)
 			Box(Modifier.fillMaxSize().padding(bottom = if (floatingAction == null) 0.dp else 72.dp)) { overlay() }
diff --git a/shared/src/jvmMain/kotlin/com/vnidrop/app/platform/PlatformSystemAppearance.jvm.kt b/shared/src/jvmMain/kotlin/com/vnidrop/app/platform/PlatformSystemAppearance.jvm.kt
index 3426d6c..23bceb5 100644
--- a/shared/src/jvmMain/kotlin/com/vnidrop/app/platform/PlatformSystemAppearance.jvm.kt
+++ b/shared/src/jvmMain/kotlin/com/vnidrop/app/platform/PlatformSystemAppearance.jvm.kt
@@ -4,8 +4,10 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.SideEffect
 import java.awt.Color
 import java.awt.EventQueue
+import java.awt.Frame
 import java.awt.Window
 import javax.swing.JFrame
+import javax.swing.JRootPane
 
 @Composable
 actual fun PlatformSystemAppearance(isDarkTheme: Boolean) {
@@ -16,10 +18,12 @@ actual fun PlatformSystemAppearance(isDarkTheme: Boolean) {
 
 internal object DesktopSystemAppearance {
 	private const val MAC_APPEARANCE_PROPERTY = "apple.awt.application.appearance"
+	private const val FULL_WINDOW_CONTENT_PROPERTY = "apple.awt.fullWindowContent"
 	private const val TRANSPARENT_TITLE_BAR_PROPERTY = "apple.awt.transparentTitleBar"
+	private const val WINDOW_TITLE_VISIBLE_PROPERTY = "apple.awt.windowTitleVisible"
 
 	fun apply(isDarkTheme: Boolean) {
-		if (!isMacOs()) return
+		if (!DesktopAppearanceBridge.isMacOs()) return
 		System.setProperty(MAC_APPEARANCE_PROPERTY, macOsAppearanceName(isDarkTheme))
 		EventQueue.invokeLater {
 			DesktopAppearanceBridge.applyNativeAppearance?.invoke(isDarkTheme)
@@ -33,27 +37,50 @@ internal object DesktopSystemAppearance {
 		if (isDarkTheme) "NSAppearanceNameDarkAqua" else "NSAppearanceNameAqua"
 
 	internal fun usesTransparentTitlebar(): Boolean = true
+	internal fun usesFullWindowContent(): Boolean = true
+	internal fun showsNativeWindowTitle(): Boolean = false
 
 	internal fun titlebarBackground(isDarkTheme: Boolean): Color =
-		if (isDarkTheme) Color(0x12, 0x12, 0x12) else Color(0xF8, 0xF8, 0xF8)
+		if (isDarkTheme) Color(0x21, 0x21, 0x21) else Color(0xF3, 0xF3, 0xF3)
 
 	private fun applyWindowChrome(window: Window, isDarkTheme: Boolean) {
 		val background = titlebarBackground(isDarkTheme)
 		window.background = background
-		(window as? JFrame)?.rootPane?.let { rootPane ->
-			// The titlebar stays native, but AppKit receives the resolved app
-			// appearance so title text and controls switch contrast at runtime.
-			rootPane.putClientProperty(TRANSPARENT_TITLE_BAR_PROPERTY, usesTransparentTitlebar())
-			rootPane.background = background
-			rootPane.contentPane.background = background
-		}
+		(window as? JFrame)?.rootPane?.let { rootPane -> applyRootPaneChrome(rootPane, background) }
 	}
 
-	private fun isMacOs(): Boolean =
-		System.getProperty("os.name").startsWith("Mac", ignoreCase = true)
+	internal fun applyRootPaneChrome(rootPane: JRootPane, background: Color) {
+		// Extending the Compose surface beneath the native titlebar lets the
+		// window chrome and sidebar share one uninterrupted background.
+		rootPane.putClientProperty(FULL_WINDOW_CONTENT_PROPERTY, usesFullWindowContent())
+		rootPane.putClientProperty(TRANSPARENT_TITLE_BAR_PROPERTY, usesTransparentTitlebar())
+		rootPane.putClientProperty(WINDOW_TITLE_VISIBLE_PROPERTY, showsNativeWindowTitle())
+		rootPane.background = background
+		rootPane.contentPane.background = background
+	}
 }
 
 object DesktopAppearanceBridge {
 	@Volatile
 	var applyNativeAppearance: ((Boolean) -> Unit)? = null
+
+	fun isMacOs(): Boolean = isMacOs(System.getProperty("os.name"))
+
+	fun toggleMaximized(window: Window) {
+		if (!isMacOs()) return
+		val frame = window as? Frame ?: return
+		EventQueue.invokeLater {
+			frame.extendedState = toggledWindowState(frame.extendedState)
+		}
+	}
+
+	internal fun isMacOs(osName: String): Boolean =
+		osName.startsWith("Mac", ignoreCase = true)
+
+	internal fun toggledWindowState(currentState: Int): Int =
+		if (currentState and Frame.MAXIMIZED_BOTH == Frame.MAXIMIZED_BOTH) {
+			Frame.NORMAL
+		} else {
+			Frame.MAXIMIZED_BOTH
+		}
 }
diff --git a/shared/src/jvmTest/kotlin/com/vnidrop/app/platform/DesktopSystemAppearanceTest.kt b/shared/src/jvmTest/kotlin/com/vnidrop/app/platform/DesktopSystemAppearanceTest.kt
index c0d7e2b..df32775 100644
--- a/shared/src/jvmTest/kotlin/com/vnidrop/app/platform/DesktopSystemAppearanceTest.kt
+++ b/shared/src/jvmTest/kotlin/com/vnidrop/app/platform/DesktopSystemAppearanceTest.kt
@@ -1,9 +1,27 @@
 package com.vnidrop.app.platform
 
+import java.awt.Color
+import java.awt.Frame
+import javax.swing.JRootPane
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
 
 class DesktopSystemAppearanceTest {
+	@Test
+	fun customWindowChromeIsMacOsOnly() {
+		assertTrue(DesktopAppearanceBridge.isMacOs("Mac OS X"))
+		assertFalse(DesktopAppearanceBridge.isMacOs("Windows 11"))
+		assertFalse(DesktopAppearanceBridge.isMacOs("Linux"))
+	}
+
+	@Test
+	fun titlebarDoubleClickTogglesMaximizedWindowState() {
+		assertEquals(Frame.MAXIMIZED_BOTH, DesktopAppearanceBridge.toggledWindowState(Frame.NORMAL))
+		assertEquals(Frame.NORMAL, DesktopAppearanceBridge.toggledWindowState(Frame.MAXIMIZED_BOTH))
+	}
+
 	@Test
 	fun macOsAppearanceNamesMatchResolvedTheme() {
 		assertEquals("NSAppearanceNameDarkAqua", DesktopSystemAppearance.macOsAppearanceName(isDarkTheme = true))
@@ -11,9 +29,9 @@ class DesktopSystemAppearanceTest {
 	}
 
 	@Test
-	fun titlebarBackgroundUsesLightAndDarkSurfaces() {
-		assertEquals(0x121212, DesktopSystemAppearance.titlebarBackground(isDarkTheme = true).rgb and 0xFFFFFF)
-		assertEquals(0xF8F8F8, DesktopSystemAppearance.titlebarBackground(isDarkTheme = false).rgb and 0xFFFFFF)
+	fun titlebarBackgroundMatchesSidebarSurface() {
+		assertEquals(0x212121, DesktopSystemAppearance.titlebarBackground(isDarkTheme = true).rgb and 0xFFFFFF)
+		assertEquals(0xF3F3F3, DesktopSystemAppearance.titlebarBackground(isDarkTheme = false).rgb and 0xFFFFFF)
 	}
 
 	@Test
@@ -21,6 +39,20 @@ class DesktopSystemAppearanceTest {
 		assertEquals(true, DesktopSystemAppearance.usesTransparentTitlebar())
 	}
 
+	@Test
+	fun composeContentExtendsUnderMacOsTitlebar() {
+		val rootPane = JRootPane()
+		val background = Color(0x21, 0x21, 0x21)
+
+		DesktopSystemAppearance.applyRootPaneChrome(rootPane, background)
+
+		assertEquals(true, rootPane.getClientProperty("apple.awt.fullWindowContent"))
+		assertEquals(true, rootPane.getClientProperty("apple.awt.transparentTitleBar"))
+		assertEquals(false, rootPane.getClientProperty("apple.awt.windowTitleVisible"))
+		assertEquals(background, rootPane.background)
+		assertEquals(background, rootPane.contentPane.background)
+	}
+
 	@Test
 	fun runtimeAppearanceCallIsFailSoft() {
 		DesktopSystemAppearance.apply(isDarkTheme = true)