diff --git a/packages/playwright-core/src/server/injected/highlight.ts b/packages/playwright-core/src/server/injected/highlight.ts
index 0487bf04d7..84cee26720 100644
--- a/packages/playwright-core/src/server/injected/highlight.ts
+++ b/packages/playwright-core/src/server/injected/highlight.ts
@@ -55,6 +55,7 @@ export class Highlight {
     const document = injectedScript.document;
     this._isUnderTest = injectedScript.isUnderTest;
     this._glassPaneElement = document.createElement('x-pw-glass');
+    this._glassPaneElement.popover = 'manual';
     this._glassPaneElement.style.position = 'fixed';
     this._glassPaneElement.style.top = '0';
     this._glassPaneElement.style.right = '0';
@@ -64,6 +65,12 @@ export class Highlight {
     this._glassPaneElement.style.pointerEvents = 'none';
     this._glassPaneElement.style.display = 'flex';
     this._glassPaneElement.style.backgroundColor = 'transparent';
+    this._glassPaneElement.style.width = 'inherit';
+    this._glassPaneElement.style.height = 'inherit';
+    this._glassPaneElement.style.padding = '0';
+    this._glassPaneElement.style.margin = '0';
+    this._glassPaneElement.style.border = 'none';
+    this._glassPaneElement.style.overflow = 'hidden';
     for (const eventName of ['click', 'auxclick', 'dragstart', 'input', 'keydown', 'keyup', 'pointerdown', 'pointerup', 'mousedown', 'mouseup', 'mouseleave', 'focus', 'scroll']) {
       this._glassPaneElement.addEventListener(eventName, e => {
         e.stopPropagation();
@@ -83,6 +90,8 @@ export class Highlight {
 
   install() {
     this._injectedScript.document.documentElement.appendChild(this._glassPaneElement);
+    // Popover is not supported in WebKit-macOS < 14.0
+    this._glassPaneElement.showPopover?.();
   }
 
   setLanguage(language: Language) {
@@ -99,6 +108,8 @@ export class Highlight {
   uninstall() {
     if (this._rafRequest)
       cancelAnimationFrame(this._rafRequest);
+    // Popover is not supported in WebKit-macOS < 14.0
+    this._glassPaneElement.hidePopover?.();
     this._glassPaneElement.remove();
   }
 
diff --git a/tests/page/page-screenshot.spec.ts b/tests/page/page-screenshot.spec.ts
index 278dd38228..fe55a21b81 100644
--- a/tests/page/page-screenshot.spec.ts
+++ b/tests/page/page-screenshot.spec.ts
@@ -482,6 +482,36 @@ it.describe('page screenshot', () => {
       })).toMatchSnapshot('should-mask-inside-iframe.png');
     });
 
+    it('should mask inside <dialog />', async ({ page, server, browserName, isElectron }) => {
+      it.info().annotations.push({ type: 'issue', description: 'https://github.com/microsoft/playwright/issues/29878' });
+      it.skip(browserName === 'webkit' && process.platform === 'darwin' && parseInt(os.release().split('.')[0], 10) < 23, 'SDKAlignedBehavior::PopoverAttributeEnabled is only enabled in macOS 14.0+');
+      it.fixme(isElectron, 'Requires a more recent Electron version');
+
+      await page.setViewportSize({ width: 500, height: 500 });
+      await page.goto(server.PREFIX + '/grid.html');
+      await page.evaluate(() => {
+        const elements = document.body.innerHTML;
+        document.body.innerHTML = '';
+        // Move all the elements of the body (grid elements) into a <dialog /> which lives on the Top-Layer.
+        const dialog = document.createElement('dialog');
+        dialog.style.padding = '0';
+        dialog.style.margin = '0';
+        dialog.style.border = 'none';
+        dialog.style.maxWidth = 'inherit';
+        dialog.style.maxHeight = 'inherit';
+        dialog.style.outline = 'none';
+        document.body.appendChild(dialog);
+        dialog.innerHTML = elements;
+        dialog.showModal();
+      });
+      expect(await page.screenshot({
+        mask: [
+          page.locator('div').nth(5),
+          page.frameLocator('#frame1').locator('div').nth(12),
+        ],
+      })).toMatchSnapshot('should-mask-inside-iframe.png');
+    });
+
     it('should mask in parallel', async ({ page, server }) => {
       await page.setViewportSize({ width: 500, height: 500 });
       await attachFrame(page, 'frame1', server.PREFIX + '/grid.html');