act-rules · giacomo-petri · Apr 16, 2026 · Apr 16, 2026 · Apr 16, 2026 · Apr 16, 2026
diff --git a/_rules/html-page-lang-b5c3f8.md b/_rules/html-page-lang-b5c3f8.md
@@ -20,6 +20,7 @@ input_aspects:
   - DOM Tree
 acknowledgments:
   authors:
+    - Giacomo Petri
     - Jey Nandakumar
   previous_authors:
     - Annika Nietzio
@@ -32,7 +33,11 @@ acknowledgments:
 This rule applies to any [document element](https://dom.spec.whatwg.org/#document-element) if it is an `html` element for which all the following are true:
 
 - is in a [top-level browsing context](https://html.spec.whatwg.org/#top-level-browsing-context); and
-- has a [node document](https://dom.spec.whatwg.org/#concept-node-document) with a [content type](https://dom.spec.whatwg.org/#concept-document-content-type) of `text/html`.
+- has a [node document](https://dom.spec.whatwg.org/#concept-node-document) with a [content type](https://dom.spec.whatwg.org/#concept-document-content-type) of `text/html`; and
+- has at least one of the following [descendant](https://dom.spec.whatwg.org/#concept-tree-descendant) that is not empty or only [whitespace][]:
+	- [text node][] that is included in the accessibility tree; or
+ 	- an element's [accessible name][] or [accessible description](https://www.w3.org/TR/accname-1.1/#dfn-accessible-description) that is exposed in the accessibility tree; or
+  	- the document's title.
 
 **Note:** `html` elements within `iframe` and `object` elements are not applicable as `iframe` and `object` elements create [nested browsing contexts](https://html.spec.whatwg.org/#nested-browsing-context). However, as these elements are meant to provide a layer of isolation, the declared language of their [parent browsing context](https://html.spec.whatwg.org/#parent-browsing-context) will likely not be inherited, making it possible for empty `lang` attributes in [nested browsing contexts](https://html.spec.whatwg.org/#nested-browsing-context) to also cause accessibility issues.
 
@@ -152,4 +157,14 @@ This rule does not apply to a `math` element.
 </math>
 ```
 
+#### Inapplicable Example 3
+
+This rule does not apply to content that is empty or contains only [whitespace][].
+
+```html
+<html>
+	<body></body>
+</html>
+```
+
 [attribute value]: #attribute-value
diff --git a/_rules/html-page-lang-matches-default-ucwvc8.md b/_rules/html-page-lang-matches-default-ucwvc8.md
@@ -23,6 +23,7 @@ input_aspects:
   - Language
 acknowledgments:
   authors:
+    - Giacomo Petri
     - Wilco Fiers
   funding:
     - WAI-Tools
@@ -39,7 +40,11 @@ This rule applies to any [document element][] if it is an `html` element for whi
 - The [document element][] has a `lang` attribute with a value that has a [known primary language tag][]; and
 - The [document element][] is in a [top-level browsing context][]; and
 - The [document element][] has a [content type][] of `text/html`; and
-- The [document element][] has a defined [default page language][].
+- The [document element][] has a defined [default page language][]; and
+- The [document element][] has at least one of the following [descendant](https://dom.spec.whatwg.org/#concept-tree-descendant) that is not empty or only [whitespace][]:
+	- [text node][] that is included in the accessibility tree; or
+ 	- an element's [accessible name][] or [accessible description](https://www.w3.org/TR/accname-1.1/#dfn-accessible-description) that is exposed in the accessibility tree; or
+  	- the document's title.
 
 ## Expectation
 
@@ -322,6 +327,16 @@ The `lang` [attribute value][] of this page is a [grandfathered tag][grandfather
 </html>
 ```
 
+#### Inapplicable Example 7
+
+This rule does not apply to content that is empty or contains only [whitespace][].
+
+```html
+<html lang="em-US">
+	<body></body>
+</html>
+```
+
 [attribute value]: #attribute-value
 [content type]: https://dom.spec.whatwg.org/#concept-document-content-type 'DOM content type, as of 2020/06/05'
 [default page language]: #default-page-language

diff --git a/_rules/html-page-lang-valid-bf051a.md b/_rules/html-page-lang-valid-bf051a.md
@@ -20,6 +20,7 @@ input_aspects:
   - DOM Tree
 acknowledgments:
   authors:
+    - Giacomo Petri
     - Jey Nandakumar
   previous_authors:
     - Annika Nietzio
@@ -33,7 +34,11 @@ This rule applies to any [document element](https://dom.spec.whatwg.org/#documen
 
 - has a `lang` attribute that is neither empty ("") nor only [ASCII whitespace](https://infra.spec.whatwg.org/#ascii-whitespace); and
 - is in a [top-level browsing context](https://html.spec.whatwg.org/#top-level-browsing-context); and
-- has a [node document](https://dom.spec.whatwg.org/#concept-node-document) with a [content type](https://dom.spec.whatwg.org/#concept-document-content-type) of `text/html`.
+- has a [node document](https://dom.spec.whatwg.org/#concept-node-document) with a [content type](https://dom.spec.whatwg.org/#concept-document-content-type) of `text/html`; and
+- has at least one of the following [descendant](https://dom.spec.whatwg.org/#concept-tree-descendant) that is not empty or only [whitespace][]:
+	- [text node][] that is included in the accessibility tree; or
+ 	- an element's [accessible name][] or [accessible description](https://www.w3.org/TR/accname-1.1/#dfn-accessible-description) that is exposed in the accessibility tree; or
+  	- the document's title.
 
 ## Expectation
 
@@ -73,18 +78,39 @@ This rule is only applicable to non-embedded HTML pages. HTML pages embedded int
 
 #### Passed Example 1
 
-This `html` element has a `lang` attribute with a [known primary language tag][].
+This `html` element has a `lang` attribute with a [known primary language tag][] and non-empty `body` content.
 
 ```html
-<html lang="FR"></html>
+<html lang="it">
+	<body>
+		<p>Amo le regole ACT!</p>
+	</body>
+</html>
 ```
 
 #### Passed Example 2
 
+This `html` element has a `lang` attribute with a [known primary language tag][] and non-empty `title`.
+
+```html
+<html lang="it">
+	<head>
+		<title>Amo le regole ACT!</title>
+	</head>
+	<body></body>
+</html>
+```
+
+#### Passed Example 3
+
 This `html` element has a `lang` attribute with a [known primary language tag][] even though the [region subtag][] is not.
 
 ```html
-<html lang="en-US-GB"></html>
+<html lang="en-US-GB">
+	<body>
+		<p lang="en">I love ACT rules!</p>
+	</body>
+</html>
 ```
 
 ### Failed
@@ -94,15 +120,23 @@ This `html` element has a `lang` attribute with a [known primary language tag][]
 This `html` element has a `lang` attribute, with no [known primary language tag][].
 
 ```html
-<html lang="em-US"></html>
+<html lang="em-US">
+	<body>
+		<p lang="en">I love ACT rules!</p>
+	</body>
+</html>
 ```
 
 #### Failed Example 2
 
 This `html` element has a `lang` attribute, with no [known primary language tag][].
 
 ```html
-<html lang="#1"></html>
+<html lang="#1">
+	<body>
+		<p lang="en">I love ACT rules!</p>
+	</body>
+</html>
 ```
 
 #### Failed Example 3
@@ -139,6 +173,16 @@ This rule does not apply to `svg` elements.
 <svg xmlns="http://www.w3.org/2000/svg" lang="fr"></svg>
 ```
 
+#### Inapplicable Example 2
+
+This rule does not apply to content that is empty or contains only [whitespace][].
+
+```html
+<html lang="em-US">
+	<body></body>
+</html>
+```
+
 [grandfathered tags]: https://www.rfc-editor.org/rfc/rfc5646.html#section-2.2.8
 [iso 639.2]: https://www.loc.gov/standards/iso639-2/php/code_list.php 'ISO 639.2: Codes for the Representation of Names of Languages'
 [region subtag]: https://www.rfc-editor.org/rfc/rfc5646.html#section-2.2.4 'Definition of region subtag'