diff --git a/CLAUDE.md b/CLAUDE.md
index 42cd4b7fe..16fc9a0e2 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -616,7 +616,7 @@ This project uses modern Angular signal-based APIs and patterns. **ALWAYS** use
 
 - Built-in web players: HTML5+hls.js, Video.js, and ArtPlayer
 - External players: MPV, VLC (via IPC to Electron backend)
-- Embedded MPV (experimental, macOS/Windows/Linux): renders mpv video inside the Electron window through a native addon. macOS uses the libmpv render API in an `NSOpenGLView`; Windows uses in-process libmpv with `--wid` against an app-owned child `HWND`; Linux spawns an out-of-process `mpv --wid=<x11-window>` controlled over a JSON IPC socket (X11/XWayland only, requires system `mpv` on PATH; subtitles/speed/aspect/recording are not exported there). mpv's own screensaver inhibition does not apply to any of these paths, so `EmbeddedMpvNativeService` holds an Electron `powerSaveBlocker` (`prevent-display-sleep`) whenever any session's status is `playing`, and releases it on pause, dispose, or shutdown. Service: `apps/electron-backend/src/app/services/embedded-mpv-native.service.ts`; full architecture: `docs/architecture/embedded-mpv-native.md`.
+- Embedded MPV (experimental, macOS/Windows/Linux): renders mpv video inside the Electron window through a native addon. macOS uses the libmpv render API in an `NSOpenGLView`; Windows uses in-process libmpv with `--wid` against an app-owned child `HWND`; Linux spawns an out-of-process `mpv --wid=<x11-window>` controlled over a JSON IPC socket (X11/XWayland only, requires system `mpv` on PATH; subtitles/speed/aspect/recording are not exported there). mpv's own screensaver inhibition does not apply to any of these paths, so `EmbeddedMpvNativeService` holds an Electron `powerSaveBlocker` (`prevent-display-sleep`) whenever any session's status is `playing`, and releases it on pause, dispose, or shutdown. Renderer bounds are CSS pixels; the service converts them to native units in the main process (`embedded-mpv-bounds.util.ts`: × page zoom everywhere, × display scale on Windows/Linux whose child windows are positioned in physical pixels; frame-copy bounds stay unscaled), and the session controller re-syncs bounds when `devicePixelRatio` changes. Service: `apps/electron-backend/src/app/services/embedded-mpv-native.service.ts`; full architecture: `docs/architecture/embedded-mpv-native.md`.
 - Embedded MPV frame-copy engine (experimental, macOS Apple Silicon + Linux
   x64 + Windows; enabled via `Settings > Playback > Embedded MPV: frame-copy
 engine` (restart required) or
diff --git a/apps/electron-backend/src/app/services/embedded-mpv-bounds.util.spec.ts b/apps/electron-backend/src/app/services/embedded-mpv-bounds.util.spec.ts
new file mode 100644
index 000000000..1996b1567
--- /dev/null
+++ b/apps/electron-backend/src/app/services/embedded-mpv-bounds.util.spec.ts
@@ -0,0 +1,122 @@
+import { EmbeddedMpvBounds } from '@iptvnator/shared/interfaces';
+import {
+    NativeViewBoundsContext,
+    toNativeViewBounds,
+} from './embedded-mpv-bounds.util';
+
+const CSS_BOUNDS: EmbeddedMpvBounds = { x: 372, y: 60, width: 578, height: 330 };
+
+function context(
+    overrides: Partial<NativeViewBoundsContext> = {}
+): NativeViewBoundsContext {
+    return {
+        platform: 'linux',
+        zoomFactor: 1,
+        displayScaleFactor: 1,
+        ...overrides,
+    };
+}
+
+describe('toNativeViewBounds', () => {
+    it('returns the input untouched at 100% zoom and 100% display scale', () => {
+        const result = toNativeViewBounds(CSS_BOUNDS, context());
+
+        expect(result).toBe(CSS_BOUNDS);
+    });
+
+    // Regression for #1145: CSS bounds were handed to XMoveResizeWindow as-is,
+    // so on a 140%-scaled Linux Mint desktop the mpv window landed at ~71% of
+    // the expected position and size, toward the window's top-left corner.
+    it('scales linux bounds by the display scale factor', () => {
+        const result = toNativeViewBounds(
+            CSS_BOUNDS,
+            context({ platform: 'linux', displayScaleFactor: 1.4 })
+        );
+
+        expect(result).toEqual({ x: 521, y: 84, width: 809, height: 462 });
+    });
+
+    it('scales win32 bounds by the display scale factor', () => {
+        const result = toNativeViewBounds(
+            { x: 100, y: 50, width: 640, height: 360 },
+            context({ platform: 'win32', displayScaleFactor: 1.25 })
+        );
+
+        expect(result).toEqual({ x: 125, y: 63, width: 800, height: 450 });
+    });
+
+    it('combines page zoom with the display scale factor', () => {
+        const result = toNativeViewBounds(
+            { x: 100, y: 50, width: 640, height: 360 },
+            context({
+                platform: 'win32',
+                zoomFactor: 1.2,
+                displayScaleFactor: 1.5,
+            })
+        );
+
+        expect(result).toEqual({ x: 180, y: 90, width: 1152, height: 648 });
+    });
+
+    it('ignores the display scale on macOS (NSView frames are in points)', () => {
+        const result = toNativeViewBounds(
+            CSS_BOUNDS,
+            context({ platform: 'darwin', displayScaleFactor: 2 })
+        );
+
+        expect(result).toBe(CSS_BOUNDS);
+    });
+
+    it('applies page zoom on macOS', () => {
+        const result = toNativeViewBounds(
+            { x: 100, y: 50, width: 640, height: 360 },
+            context({
+                platform: 'darwin',
+                zoomFactor: 1.5,
+                displayScaleFactor: 2,
+            })
+        );
+
+        expect(result).toEqual({ x: 150, y: 75, width: 960, height: 540 });
+    });
+
+    it('keeps vertically adjacent rects seamless under fractional scales', () => {
+        // 42 × 1.25 and 153 × 1.25 both land on .5/.25 fractions: rounding
+        // x/y/width/height independently would misplace the shared edge by
+        // 1px, while edge-based rounding keeps the rects flush.
+        const scale = context({ displayScaleFactor: 1.25 });
+        const upper = toNativeViewBounds(
+            { x: 0, y: 42, width: 500, height: 111 },
+            scale
+        );
+        const lower = toNativeViewBounds(
+            { x: 0, y: 153, width: 500, height: 90 },
+            scale
+        );
+
+        expect(upper.y + upper.height).toBe(lower.y);
+    });
+
+    it('keeps hidden bounds offscreen and at least 1x1', () => {
+        const result = toNativeViewBounds(
+            { x: -100000, y: -100000, width: 1, height: 1 },
+            context({ displayScaleFactor: 1.5 })
+        );
+
+        expect(result.x).toBeLessThanOrEqual(-100000);
+        expect(result.y).toBeLessThanOrEqual(-100000);
+        expect(result.width).toBeGreaterThanOrEqual(1);
+        expect(result.height).toBeGreaterThanOrEqual(1);
+    });
+
+    it('treats non-finite or non-positive factors as 100%', () => {
+        for (const zoomFactor of [Number.NaN, 0, -1, Number.POSITIVE_INFINITY]) {
+            expect(
+                toNativeViewBounds(
+                    CSS_BOUNDS,
+                    context({ zoomFactor, displayScaleFactor: zoomFactor })
+                )
+            ).toBe(CSS_BOUNDS);
+        }
+    });
+});
diff --git a/apps/electron-backend/src/app/services/embedded-mpv-bounds.util.ts b/apps/electron-backend/src/app/services/embedded-mpv-bounds.util.ts
new file mode 100644
index 000000000..1c539bf70
--- /dev/null
+++ b/apps/electron-backend/src/app/services/embedded-mpv-bounds.util.ts
@@ -0,0 +1,57 @@
+import { EmbeddedMpvBounds } from '@iptvnator/shared/interfaces';
+
+export interface NativeViewBoundsContext {
+    platform: NodeJS.Platform;
+    /** Page zoom factor of the main window's webContents (1 = 100%). */
+    zoomFactor: number;
+    /** Scale factor of the display hosting the main window (1 = 96 dpi). */
+    displayScaleFactor: number;
+}
+
+/**
+ * Converts renderer-measured bounds (CSS pixels from
+ * getBoundingClientRect()) into the coordinate space the native-view
+ * engines position their OS windows in: physical pixels for the win32
+ * child HWND (SetWindowPos) and the linux child X11 window
+ * (XMoveResizeWindow), points — device-independent pixels — for the macOS
+ * NSView (setFrame). CSS pixels match points only at 100% page zoom and
+ * match physical pixels only at 100% page zoom AND 100% display scale, so
+ * every platform scales by the zoom factor and win32/linux additionally by
+ * the display scale factor (#1145).
+ *
+ * Edges are scaled before deriving width/height so rounding cannot open
+ * 1px seams between the native video window and the surrounding DOM UI.
+ */
+export function toNativeViewBounds(
+    bounds: EmbeddedMpvBounds,
+    context: NativeViewBoundsContext
+): EmbeddedMpvBounds {
+    const scale = resolveNativeViewScale(context);
+    if (scale === 1) {
+        return bounds;
+    }
+
+    const left = Math.round(bounds.x * scale);
+    const top = Math.round(bounds.y * scale);
+    const right = Math.round((bounds.x + bounds.width) * scale);
+    const bottom = Math.round((bounds.y + bounds.height) * scale);
+
+    return {
+        x: left,
+        y: top,
+        width: Math.max(1, right - left),
+        height: Math.max(1, bottom - top),
+    };
+}
+
+function resolveNativeViewScale(context: NativeViewBoundsContext): number {
+    const zoomFactor = sanitizeFactor(context.zoomFactor);
+    if (context.platform === 'darwin') {
+        return zoomFactor;
+    }
+    return zoomFactor * sanitizeFactor(context.displayScaleFactor);
+}
+
+function sanitizeFactor(value: number): number {
+    return Number.isFinite(value) && value > 0 ? value : 1;
+}
diff --git a/apps/electron-backend/src/app/services/embedded-mpv-native.service.spec.ts b/apps/electron-backend/src/app/services/embedded-mpv-native.service.spec.ts
index 1f85402b2..2b89e1888 100644
--- a/apps/electron-backend/src/app/services/embedded-mpv-native.service.spec.ts
+++ b/apps/electron-backend/src/app/services/embedded-mpv-native.service.spec.ts
@@ -41,20 +41,29 @@ const appMock = {
     commandLine: commandLineMock,
 };
 
+const screenGetDisplayMatchingMock = jest.fn();
+
 jest.mock('electron', () => ({
     app: appMock,
     powerSaveBlocker: powerSaveBlockerMock,
+    screen: { getDisplayMatching: screenGetDisplayMatchingMock },
 }));
 
 const mainWindowSendMock = jest.fn();
 const mainWindowWebContentsOnMock = jest.fn();
+const mainWindowGetZoomFactorMock = jest.fn<number, []>();
 const mainWindowGetNativeWindowHandleMock = jest.fn<Buffer, []>(() =>
     Buffer.alloc(8)
 );
 const mainWindowMock = {
     isDestroyed: () => false,
     getNativeWindowHandle: mainWindowGetNativeWindowHandleMock,
-    webContents: { send: mainWindowSendMock, on: mainWindowWebContentsOnMock },
+    getBounds: () => ({ x: 0, y: 0, width: 1280, height: 720 }),
+    webContents: {
+        send: mainWindowSendMock,
+        on: mainWindowWebContentsOnMock,
+        getZoomFactor: mainWindowGetZoomFactorMock,
+    },
 };
 
 jest.mock('../app', () => ({
@@ -155,6 +164,10 @@ describe('EmbeddedMpvNativeService power blocker', () => {
         mainWindowGetNativeWindowHandleMock.mockReturnValue(Buffer.alloc(8));
         mainWindowSendMock.mockReset();
         mainWindowWebContentsOnMock.mockReset();
+        mainWindowGetZoomFactorMock.mockReset();
+        mainWindowGetZoomFactorMock.mockReturnValue(1);
+        screenGetDisplayMatchingMock.mockReset();
+        screenGetDisplayMatchingMock.mockReturnValue({ scaleFactor: 1 });
         appMock.isPackaged = true;
 
         tempDirs = [];
@@ -440,6 +453,95 @@ describe('EmbeddedMpvNativeService power blocker', () => {
         });
     });
 
+    describe('native view bounds scaling', () => {
+        afterEach(() => {
+            delete process.env.IPTVNATOR_ENABLE_EMBEDDED_MPV_FRAME_COPY;
+        });
+
+        it('converts CSS bounds to physical pixels for the native engine on scaled displays', () => {
+            // Regression for #1145: the win32/linux engines position their
+            // child window in physical pixels, so renderer CSS bounds must
+            // be multiplied by the display scale before reaching the addon.
+            Object.defineProperty(process, 'platform', { value: 'linux' });
+            screenGetDisplayMatchingMock.mockReturnValue({ scaleFactor: 1.5 });
+            addon.createSession.mockReturnValueOnce('s-scaled');
+            addon.getSessionSnapshot.mockReturnValue(snapshot('loading'));
+
+            const cssBounds = { x: 100, y: 40, width: 640, height: 360 };
+            service.createSession(cssBounds, '', 1);
+            service.setBounds('s-scaled', cssBounds);
+
+            const physicalBounds = { x: 150, y: 60, width: 960, height: 540 };
+            expect(addon.createSession).toHaveBeenCalledWith(
+                expect.any(Buffer),
+                physicalBounds,
+                '',
+                1
+            );
+            expect(addon.setBounds).toHaveBeenCalledWith(
+                's-scaled',
+                physicalBounds
+            );
+        });
+
+        it('applies page zoom but not the display scale on macOS', () => {
+            // NSView frames are in points (device-independent pixels): only
+            // the webContents zoom factor separates them from CSS pixels.
+            screenGetDisplayMatchingMock.mockReturnValue({ scaleFactor: 2 });
+            mainWindowGetZoomFactorMock.mockReturnValue(1.25);
+            addon.createSession.mockReturnValueOnce('s-zoom');
+            addon.getSessionSnapshot.mockReturnValue(snapshot('loading'));
+
+            service.createSession({ x: 0, y: 0, width: 100, height: 100 }, '', 1);
+
+            expect(addon.createSession).toHaveBeenCalledWith(
+                expect.any(Buffer),
+                { x: 0, y: 0, width: 125, height: 125 },
+                '',
+                1
+            );
+        });
+
+        it('passes frame-copy bounds through unscaled', () => {
+            // The frame-copy engine paints into a DOM canvas laid out in CSS
+            // pixels; its adapter applies the display scale to the render
+            // size itself, so a second scaling pass here would double it.
+            Object.defineProperty(process, 'platform', { value: 'linux' });
+            process.env.IPTVNATOR_ENABLE_EMBEDDED_MPV_FRAME_COPY = '1';
+            mockIsFrameCopyRuntimeUsable.mockReturnValue(true);
+            mockGetFrameCopyRuntimeAvailability.mockReturnValue({
+                usable: true,
+            });
+            screenGetDisplayMatchingMock.mockReturnValue({ scaleFactor: 1.5 });
+            const frameCopyAddon = createMockAddon();
+            frameCopyAddon.createSession.mockReturnValueOnce('s-fc-bounds');
+            frameCopyAddon.getSessionSnapshot.mockReturnValue(
+                snapshot('loading')
+            );
+            (
+                service as unknown as { frameCopyAdapter: MockAddon }
+            ).frameCopyAdapter = frameCopyAddon;
+
+            service.createSession(BOUNDS, '', 1);
+            service.setBounds('s-fc-bounds', BOUNDS);
+
+            expect(frameCopyAddon.createSession).toHaveBeenCalledWith(
+                Buffer.alloc(0),
+                BOUNDS,
+                '',
+                1
+            );
+            expect(frameCopyAddon.setBounds).toHaveBeenCalledWith(
+                's-fc-bounds',
+                BOUNDS
+            );
+
+            // Dispose while the frame-copy env is still set so teardown
+            // dispatches to the adapter that owns the session.
+            service.disposeSession('s-fc-bounds');
+        });
+    });
+
     it('does not acquire a blocker for a loading session', () => {
         startSession('s1', snapshot('loading'));
         expect(powerSaveBlockerMock.start).not.toHaveBeenCalled();
diff --git a/apps/electron-backend/src/app/services/embedded-mpv-native.service.ts b/apps/electron-backend/src/app/services/embedded-mpv-native.service.ts
index d30ad596f..8142fb66b 100644
--- a/apps/electron-backend/src/app/services/embedded-mpv-native.service.ts
+++ b/apps/electron-backend/src/app/services/embedded-mpv-native.service.ts
@@ -27,6 +27,7 @@ import {
     EMBEDDED_MPV_SESSION_UPDATE,
     ResolvedPortalPlayback,
 } from '@iptvnator/shared/interfaces';
+import { toNativeViewBounds } from './embedded-mpv-bounds.util';
 import { EmbeddedMpvFrameCopyAdapter } from './embedded-mpv-frame-copy.adapter';
 import {
     getFrameCopyRuntimeAvailability,
@@ -201,6 +202,36 @@ export class EmbeddedMpvNativeService {
         }
     }
 
+    private getMainWindowZoomFactor(): number {
+        try {
+            if (!App.mainWindow || App.mainWindow.isDestroyed()) {
+                return 1;
+            }
+            return App.mainWindow.webContents.getZoomFactor();
+        } catch {
+            return 1;
+        }
+    }
+
+    /**
+     * Renderer bounds arrive in CSS pixels; the native-view engines position
+     * OS windows in physical pixels (win32/linux) or points (macOS), so at
+     * page zoom or display scale ≠ 100% the raw values land the video toward
+     * the window's top-left corner at a fraction of its size (#1145). The
+     * frame-copy engine must bypass this: it paints into a DOM canvas laid
+     * out in CSS pixels, and its adapter already applies the display scale
+     * to the render size itself.
+     */
+    private scaleBoundsForNativeView(
+        bounds: EmbeddedMpvBounds
+    ): EmbeddedMpvBounds {
+        return toNativeViewBounds(bounds, {
+            platform: process.platform,
+            zoomFactor: this.getMainWindowZoomFactor(),
+            displayScaleFactor: this.getMainWindowScaleFactor(),
+        });
+    }
+
     private detectCapabilities(): EmbeddedMpvCapabilities {
         if (this.isFrameCopyEngineActive()) {
             return {
@@ -419,14 +450,15 @@ export class EmbeddedMpvNativeService {
         // embed into the window at all. Derive the skip from the dispatched
         // addon rather than re-evaluating the engine gate, so the two
         // decisions cannot disagree.
-        const windowHandle =
-            this.frameCopyAdapter && addon === this.frameCopyAdapter
-                ? Buffer.alloc(0)
-                : this.getMainWindowHandle();
+        const usesFrameCopyAddon =
+            this.frameCopyAdapter !== null && addon === this.frameCopyAdapter;
+        const windowHandle = usesFrameCopyAddon
+            ? Buffer.alloc(0)
+            : this.getMainWindowHandle();
         const startedAt = new Date().toISOString();
         const sessionId = addon.createSession(
             windowHandle,
-            bounds,
+            usesFrameCopyAddon ? bounds : this.scaleBoundsForNativeView(bounds),
             title,
             initialVolume
         );
@@ -478,7 +510,13 @@ export class EmbeddedMpvNativeService {
 
     setBounds(sessionId: string, bounds: EmbeddedMpvBounds): void {
         this.assertEmbeddedMpvEnabled();
-        this.getAddon().setBounds(sessionId, bounds);
+        const addon = this.getAddon();
+        const usesFrameCopyAddon =
+            this.frameCopyAdapter !== null && addon === this.frameCopyAdapter;
+        addon.setBounds(
+            sessionId,
+            usesFrameCopyAddon ? bounds : this.scaleBoundsForNativeView(bounds)
+        );
     }
 
     setPaused(sessionId: string, paused: boolean): EmbeddedMpvSession | null {
diff --git a/docs/architecture/embedded-mpv-native.md b/docs/architecture/embedded-mpv-native.md
index 19feed60d..2edaa58e7 100644
--- a/docs/architecture/embedded-mpv-native.md
+++ b/docs/architecture/embedded-mpv-native.md
@@ -150,9 +150,10 @@ The flow is:
    native-view, it starts `mpv --wid=<x11-window>` in a separate process with a
    private JSON IPC socket. Frame-copy instead uses the per-session helper
    described below.
-9. Resize, scroll, and fullscreen changes are measured in Angular and sent
-   through bounds sync. Native-view uses them to align the platform host;
-   frame-copy uses them to resize helper rendering and the canvas frame source.
+9. Resize, scroll, fullscreen, and devicePixelRatio changes are measured in
+   Angular and sent through bounds sync. Native-view uses them to align the
+   platform host; frame-copy uses them to resize helper rendering and the
+   canvas frame source.
 10. Playback controls remain IPTVnator-owned Angular UI. Frame-copy uses the
     shared `app-player-controls` overlay through
     `EmbeddedMpvControlsAdapter`; native-view keeps its compositor-safe fixed
@@ -595,6 +596,35 @@ there is no `HIDDEN_BOUNDS`, popover cutout, or reserved dock height. Dialogs
 and controls layer naturally over the canvas, while bounds sync still updates
 the helper's render size.
 
+### Coordinate spaces (CSS → native units)
+
+The renderer measures bounds in CSS pixels (`getBoundingClientRect()`), but
+the native-view engines position OS windows, not DOM nodes: the win32 child
+`HWND` (`SetWindowPos`) and the Linux child X11 window (`XMoveResizeWindow`)
+live in physical pixels, and the macOS `NSView` (`setFrame`) lives in points
+(device-independent pixels). CSS values match points only at 100% page zoom
+and match physical pixels only at 100% page zoom AND 100% display scale.
+`EmbeddedMpvNativeService` therefore converts every native-view bounds payload
+in the main process (`toNativeViewBounds` in `embedded-mpv-bounds.util.ts`):
+all platforms scale by the webContents zoom factor, win32/linux additionally
+by the scale factor of the display hosting the window. Edges are scaled
+before deriving width/height so rounding cannot open 1px seams against the
+surrounding DOM UI. Skipping this conversion is issue #1145: on scaled
+displays (Windows 125%, Linux fractional scaling, HiDPI TVs) the video landed
+toward the window's top-left corner at `1/scale` of its size, in windowed and
+fullscreen mode alike.
+
+Frame-copy bounds bypass the conversion: the canvas is laid out by the DOM in
+CSS pixels, and the frame-copy adapter already multiplies the render size by
+the display scale factor itself.
+
+Because a monitor change can rescale this mapping without resizing the host
+element (moving the window to a display with a different scale keeps the DIP
+layout), the session controller also watches `devicePixelRatio` through a
+re-armed `matchMedia('(resolution: …dppx)')` query and re-syncs bounds when
+it changes; page zoom changes are covered by the same watch plus the ordinary
+resize-driven syncs.
+
 ### Controls ownership by engine
 
 `EmbeddedMpvPlayerComponent` selects one control owner from
diff --git a/libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-session-controller.dpr.spec.ts b/libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-session-controller.dpr.spec.ts
new file mode 100644
index 000000000..79cf74df6
--- /dev/null
+++ b/libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-session-controller.dpr.spec.ts
@@ -0,0 +1,213 @@
+import { TestBed } from '@angular/core/testing';
+import {
+    EmbeddedMpvSession,
+    ResolvedPortalPlayback,
+} from '@iptvnator/shared/interfaces';
+import { EmbeddedMpvSessionController } from './embedded-mpv-session-controller';
+
+/**
+ * Moving the window to a display with a different scale (or changing the
+ * page zoom) rescales the CSS→native mapping the backend applies to bounds,
+ * without necessarily resizing the host element. The controller watches
+ * devicePixelRatio through a re-armed matchMedia query and re-syncs bounds
+ * when it changes (#1145).
+ */
+describe('EmbeddedMpvSessionController devicePixelRatio watch', () => {
+    class FakeMediaQueryList {
+        private readonly listeners = new Set<() => void>();
+
+        constructor(readonly media: string) {}
+
+        addEventListener(_type: 'change', listener: () => void): void {
+            this.listeners.add(listener);
+        }
+
+        removeEventListener(_type: 'change', listener: () => void): void {
+            this.listeners.delete(listener);
+        }
+
+        fire(): void {
+            for (const listener of [...this.listeners]) {
+                listener();
+            }
+        }
+
+        get listenerCount(): number {
+            return this.listeners.size;
+        }
+    }
+
+    let electron: {
+        platform: string;
+        getEmbeddedMpvSupport: jest.Mock;
+        prepareEmbeddedMpv: jest.Mock;
+        createEmbeddedMpvSession: jest.Mock;
+        loadEmbeddedMpvPlayback: jest.Mock;
+        disposeEmbeddedMpvSession: jest.Mock;
+        setEmbeddedMpvBounds: jest.Mock;
+        onEmbeddedMpvSessionUpdate: jest.Mock;
+    };
+    let mediaQueries: FakeMediaQueryList[];
+
+    beforeEach(() => {
+        electron = {
+            platform: 'win32',
+            getEmbeddedMpvSupport: jest
+                .fn()
+                .mockResolvedValue({ supported: true, platform: 'win32' }),
+            prepareEmbeddedMpv: jest
+                .fn()
+                .mockResolvedValue({ supported: true, platform: 'win32' }),
+            createEmbeddedMpvSession: jest
+                .fn()
+                .mockResolvedValue(createSession()),
+            loadEmbeddedMpvPlayback: jest.fn().mockResolvedValue(undefined),
+            disposeEmbeddedMpvSession: jest.fn().mockResolvedValue(undefined),
+            setEmbeddedMpvBounds: jest.fn().mockResolvedValue(undefined),
+            onEmbeddedMpvSessionUpdate: jest.fn(() => jest.fn()),
+        };
+        Object.defineProperty(window, 'electron', {
+            configurable: true,
+            value: electron,
+        });
+
+        mediaQueries = [];
+        Object.defineProperty(window, 'matchMedia', {
+            configurable: true,
+            value: (media: string) => {
+                const query = new FakeMediaQueryList(media);
+                mediaQueries.push(query);
+                return query;
+            },
+        });
+        Object.defineProperty(window, 'devicePixelRatio', {
+            configurable: true,
+            value: 1,
+        });
+        Object.defineProperty(globalThis, 'ResizeObserver', {
+            configurable: true,
+            value: class MockResizeObserver {
+                observe = jest.fn();
+                disconnect = jest.fn();
+            },
+        });
+        Object.defineProperty(window, 'requestAnimationFrame', {
+            configurable: true,
+            value: (callback: FrameRequestCallback) =>
+                window.setTimeout(() => callback(0), 0),
+        });
+        Object.defineProperty(window, 'cancelAnimationFrame', {
+            configurable: true,
+            value: (handle: number) => window.clearTimeout(handle),
+        });
+
+        TestBed.configureTestingModule({
+            providers: [EmbeddedMpvSessionController],
+        });
+    });
+
+    afterEach(() => {
+        TestBed.resetTestingModule();
+        delete (window as unknown as { electron?: unknown }).electron;
+        delete (window as unknown as { matchMedia?: unknown }).matchMedia;
+        jest.restoreAllMocks();
+    });
+
+    it('re-syncs bounds and re-arms the query when devicePixelRatio changes', async () => {
+        const controller = TestBed.inject(EmbeddedMpvSessionController);
+        const teardown = controller.startSession(
+            createHost(),
+            createPlayback(),
+            0.5
+        );
+        await waitFor(
+            () => controller.sessionId() === 'mpv-1',
+            'session to start'
+        );
+
+        expect(mediaQueries.length).toBe(1);
+        expect(mediaQueries[0].media).toBe('(resolution: 1dppx)');
+        electron.setEmbeddedMpvBounds.mockClear();
+
+        // Simulate a move to a 150%-scaled display.
+        Object.defineProperty(window, 'devicePixelRatio', {
+            configurable: true,
+            value: 1.5,
+        });
+        mediaQueries[0].fire();
+        await waitFor(
+            () => electron.setEmbeddedMpvBounds.mock.calls.length > 0,
+            'bounds re-sync after dPR change'
+        );
+
+        // The stale query is released and a new one tracks the new ratio.
+        expect(mediaQueries[0].listenerCount).toBe(0);
+        expect(mediaQueries.length).toBe(2);
+        expect(mediaQueries[1].media).toBe('(resolution: 1.5dppx)');
+
+        // A second display change must fire through the re-armed query.
+        electron.setEmbeddedMpvBounds.mockClear();
+        mediaQueries[1].fire();
+        await waitFor(
+            () => electron.setEmbeddedMpvBounds.mock.calls.length > 0,
+            'bounds re-sync after second dPR change'
+        );
+
+        teardown();
+        expect(mediaQueries[mediaQueries.length - 1].listenerCount).toBe(0);
+    });
+});
+
+function createHost(): HTMLElement {
+    return {
+        getBoundingClientRect: () => ({
+            left: 10,
+            top: 20,
+            width: 640,
+            height: 360,
+        }),
+    } as HTMLElement;
+}
+
+function createPlayback(): ResolvedPortalPlayback {
+    return {
+        streamUrl: 'https://example.com/movie.mp4',
+        title: 'Example Movie',
+    };
+}
+
+function createSession(): EmbeddedMpvSession {
+    return {
+        id: 'mpv-1',
+        title: 'Example Movie',
+        streamUrl: 'https://example.com/movie.mp4',
+        status: 'playing',
+        positionSeconds: 0,
+        durationSeconds: null,
+        volume: 0.5,
+        audioTracks: [],
+        selectedAudioTrackId: null,
+        subtitleTracks: [],
+        selectedSubtitleTrackId: null,
+        playbackSpeed: 1,
+        aspectOverride: 'no',
+        recording: { active: false },
+        startedAt: '2026-07-19T00:00:00.000Z',
+        updatedAt: '2026-07-19T00:00:01.000Z',
+    };
+}
+
+async function waitFor(
+    condition: () => boolean,
+    description: string
+): Promise<void> {
+    const deadline = Date.now() + 1_000;
+    while (Date.now() < deadline) {
+        if (condition()) {
+            return;
+        }
+        await Promise.resolve();
+        await new Promise((resolve) => window.setTimeout(resolve, 0));
+    }
+    throw new Error(`Timed out waiting for ${description}`);
+}
diff --git a/libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-session-controller.ts b/libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-session-controller.ts
index 36e6e11cb..f760bec97 100644
--- a/libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-session-controller.ts
+++ b/libs/ui/playback/src/lib/embedded-mpv-player/embedded-mpv-session-controller.ts
@@ -151,6 +151,31 @@ export class EmbeddedMpvSessionController {
         window.addEventListener('resize', scheduleBoundsSync);
         window.addEventListener('scroll', scheduleBoundsSync, true);
 
+        // Page zoom and monitor DPI rescale the CSS→native-pixel mapping the
+        // backend applies to these bounds. Moving the window to a display
+        // with a different scale can keep the CSS layout identical (no
+        // resize, no ResizeObserver), so watch devicePixelRatio through a
+        // re-armed matchMedia query and re-sync when it changes.
+        let detachDprWatch: (() => void) | null = null;
+        const watchDevicePixelRatio = () => {
+            detachDprWatch?.();
+            detachDprWatch = null;
+            const query = window.matchMedia?.(
+                `(resolution: ${window.devicePixelRatio}dppx)`
+            );
+            if (!query) {
+                return;
+            }
+            const onChange = () => {
+                watchDevicePixelRatio();
+                scheduleBoundsSync();
+            };
+            query.addEventListener('change', onChange);
+            detachDprWatch = () =>
+                query.removeEventListener('change', onChange);
+        };
+        watchDevicePixelRatio();
+
         const create = async () => {
             this.session.set(createLoadingSession(playback, initialVolume));
             await waitForStartupPaint();
@@ -237,6 +262,8 @@ export class EmbeddedMpvSessionController {
             resizeObserver.disconnect();
             window.removeEventListener('resize', scheduleBoundsSync);
             window.removeEventListener('scroll', scheduleBoundsSync, true);
+            detachDprWatch?.();
+            detachDprWatch = null;
 
             if (this.activeBoundsSync === scheduleBoundsSync) {
                 this.activeBoundsSync = null;