diff --git a/documentation/global-ui-controls.md b/documentation/global-ui-controls.md
index 046ed06..e84677a 100644
--- a/documentation/global-ui-controls.md
+++ b/documentation/global-ui-controls.md
@@ -80,19 +80,20 @@ sound button, and fullscreen for the fullscreen button.
 When runtime is embedded in an iframe, the fullscreen control requests
 fullscreen on the embedding iframe first when same-origin access is available.
 For cross-origin wrappers it posts `tour-builder:request-fullscreen` to
-`window.parent` before attempting child-document fullscreen, because a
-permissions-policy rejection inside the iframe can consume the user activation
-needed by the parent fallback. If the iframe itself grants fullscreen but the
-parent does not listen for the message, the child-document fullscreen fallback
-can still enter fullscreen. Standalone runtime pages use the browser Fullscreen
-API for the presentation document. Exit attempts post
-`tour-builder:exit-fullscreen`.
+`window.parent` and, for nested iframe wrappers, `window.top` before attempting
+child-document fullscreen, because a permissions-policy rejection inside the
+iframe can consume the user activation needed by the parent fallback. If the
+iframe itself grants fullscreen but the parent does not listen for the message,
+the child-document fullscreen fallback can still enter fullscreen. Standalone
+runtime pages use the browser Fullscreen API for the presentation document.
+Exit attempts post `tour-builder:exit-fullscreen` to the same parent/top
+targets.
 
 Browser fullscreen is not equivalent for top-level pages and iframes. A
 top-level runtime page can request document fullscreen from a user click, while
 a cross-origin iframe normally needs `allow="fullscreen"` / `allowfullscreen`
-or a parent page that handles `tour-builder:request-fullscreen` and fullscreens
-the iframe element.
+or a parent/top page that handles `tour-builder:request-fullscreen` and
+fullscreens the iframe element.
 
 The runtime keeps a local fullscreen-active state after an embedded parent
 fullscreen request because the child document may not expose a local
diff --git a/frontend/docs/runtime-presentation.md b/frontend/docs/runtime-presentation.md
index e342131..19ca0ff 100644
--- a/frontend/docs/runtime-presentation.md
+++ b/frontend/docs/runtime-presentation.md
@@ -167,16 +167,17 @@ Custom icons use each control's `defaultIconUrl` and `activeIconUrl`; empty
 values fall back to the built-in MDI icons.
 Embedded runtime fullscreen requests the embedding iframe first when same-origin
 access is available. For cross-origin wrappers it posts
-`tour-builder:request-fullscreen` to the parent before attempting
-child-document fullscreen, so a permissions-policy rejection inside the iframe
-does not consume the user activation needed by the parent fallback. If the
-iframe itself grants fullscreen but the parent does not listen for the message,
-the child-document fullscreen fallback can still enter fullscreen. Standalone
-runtime pages use native document fullscreen. Exit from cross-origin wrapper
-fullscreen posts `tour-builder:exit-fullscreen`.
+`tour-builder:request-fullscreen` to the parent and, for nested iframe wrappers,
+the top window before attempting child-document fullscreen, so a
+permissions-policy rejection inside the iframe does not consume the user
+activation needed by the parent fallback. If the iframe itself grants fullscreen
+but the parent does not listen for the message, the child-document fullscreen
+fallback can still enter fullscreen. Standalone runtime pages use native
+document fullscreen. Exit from cross-origin wrapper fullscreen posts
+`tour-builder:exit-fullscreen` to the same parent/top targets.
 Top-level runtime pages can request document fullscreen from a user click, but
 cross-origin iframe embeds normally require `allow="fullscreen"` /
-`allowfullscreen` or a parent listener that fullscreens the iframe element.
+`allowfullscreen` or a parent/top listener that fullscreens the iframe element.
 After a parent iframe fullscreen request, `useRuntimeFullscreen` keeps the
 fullscreen button in its active state even when the child document does not
 expose `document.fullscreenElement`; native enter/exit events still clear or set
@@ -1231,11 +1232,11 @@ actual browser operations to `runtimeFullscreen.actions.ts` and
 `lib/fullscreen.ts`:
 
 - enter standalone: request document fullscreen
-- enter embedded: request same-origin embedding iframe fullscreen or post parent
-  `tour-builder:request-fullscreen`, then fall back to child-document fullscreen
-  when iframe permissions allow it
+- enter embedded: request same-origin embedding iframe fullscreen or post
+  `tour-builder:request-fullscreen` to parent/top wrappers, then fall back to
+  child-document fullscreen when iframe permissions allow it
 - exit: exit native fullscreen when the child document owns it; otherwise post
-  `tour-builder:exit-fullscreen` to the parent wrapper
+  `tour-builder:exit-fullscreen` to parent/top wrappers
 - state: preserve active fullscreen state for parent iframe fullscreen requests
   that do not create a child `document.fullscreenElement`
 - events: listen to both `fullscreenchange` and `webkitfullscreenchange`
diff --git a/frontend/src/lib/fullscreen.test.ts b/frontend/src/lib/fullscreen.test.ts
index de33882..40a7d84 100644
--- a/frontend/src/lib/fullscreen.test.ts
+++ b/frontend/src/lib/fullscreen.test.ts
@@ -73,6 +73,44 @@ test('requestDocumentFullscreen asks the parent before child fullscreen when emb
   ]);
 });
 
+test('requestDocumentFullscreen also asks the top window when embedded in nested frames', async () => {
+  const calls: string[] = [];
+  const parent = {
+    postMessage: (message: unknown, targetOrigin: string) => {
+      calls.push(`parent:${targetOrigin}:${JSON.stringify(message)}`);
+    },
+  };
+  const top = {
+    postMessage: (message: unknown, targetOrigin: string) => {
+      calls.push(`top:${targetOrigin}:${JSON.stringify(message)}`);
+    },
+  };
+
+  setBrowserGlobals({
+    windowValue: {
+      parent,
+      top,
+      frameElement: null,
+    },
+    documentValue: {
+      documentElement: {
+        requestFullscreen: async () => {
+          calls.push('document-fullscreen');
+        },
+      },
+    },
+  });
+
+  const entered = await requestDocumentFullscreen('runtime-global-control');
+
+  assert.equal(entered, true);
+  assert.deepEqual(calls, [
+    'parent:*:{"type":"tour-builder:request-fullscreen","source":"runtime-global-control"}',
+    'top:*:{"type":"tour-builder:request-fullscreen","source":"runtime-global-control"}',
+    'document-fullscreen',
+  ]);
+});
+
 test('requestDocumentFullscreen returns parent request when embedded child fullscreen is blocked', async () => {
   const calls: string[] = [];
   const parent = {
diff --git a/frontend/src/lib/fullscreen.ts b/frontend/src/lib/fullscreen.ts
index dab39b6..c71966d 100644
--- a/frontend/src/lib/fullscreen.ts
+++ b/frontend/src/lib/fullscreen.ts
@@ -74,13 +74,16 @@ const requestSameOriginEmbeddingFrameFullscreen =
 const requestParentFullscreen = (source: string): boolean => {
   if (!isEmbeddedWindow()) return false;
 
-  window.parent.postMessage(
-    {
-      type: 'tour-builder:request-fullscreen',
-      source,
-    },
-    '*',
-  );
+  const message = {
+    type: 'tour-builder:request-fullscreen',
+    source,
+  };
+
+  window.parent.postMessage(message, '*');
+
+  if (window.top && window.top !== window.parent) {
+    window.top.postMessage(message, '*');
+  }
 
   return true;
 };
@@ -127,13 +130,16 @@ export const requestDocumentFullscreen = async (
 export const requestParentFullscreenExit = (source = 'runtime'): boolean => {
   if (!isEmbeddedWindow()) return false;
 
-  window.parent.postMessage(
-    {
-      type: 'tour-builder:exit-fullscreen',
-      source,
-    },
-    '*',
-  );
+  const message = {
+    type: 'tour-builder:exit-fullscreen',
+    source,
+  };
+
+  window.parent.postMessage(message, '*');
+
+  if (window.top && window.top !== window.parent) {
+    window.top.postMessage(message, '*');
+  }
 
   return true;
 };