From e23e17a9021e1916a03a13d57e1f44e612edec96 Mon Sep 17 00:00:00 2001
From: Vadim Makeev <vmakeev@mozilla.com>
Date: Tue, 9 Apr 2024 19:29:24 +0200
Subject: [PATCH 1/7] Add experimental h1 UA styles removal

---
 .../firefox/experimental_features/index.md    | 46 ++++++++++++++++++-
 .../mozilla/firefox/releases/125/index.md     |  4 ++
 2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/files/en-us/mozilla/firefox/experimental_features/index.md b/files/en-us/mozilla/firefox/experimental_features/index.md
index 7da591397c8e52a..d844d53c4ca40a6 100644
--- a/files/en-us/mozilla/firefox/experimental_features/index.md
+++ b/files/en-us/mozilla/firefox/experimental_features/index.md
@@ -819,7 +819,7 @@ The [`text-wrap`](/en-US/docs/Web/CSS/text-wrap) CSS property values `balance` a
   </tbody>
 </table>
 
-#### Vendor-prefixed transform properties
+### Vendor-prefixed transform properties
 
 The `-moz-` prefixed [CSS transform](/en-US/docs/Web/CSS/CSS_transforms) properties have been disabled in the Nightly release via the `layout.css.prefixes.transforms` preference being set to `false` ([Firefox bug 1855763](https://bugzil.la/1855763)).
 Specifically, the disabled properties are:
@@ -869,7 +869,7 @@ Specifically, the disabled properties are:
   </tbody>
 </table>
 
-#### Vendor-prefixed transition properties
+### Vendor-prefixed transition properties
 
 The `-moz-` prefixed [CSS transitions](/en-US/docs/Web/CSS/CSS_transitions) properties have been disabled in the Nightly release via the `layout.css.prefixes.transitions` preference being set to `false` ([Firefox bug 1855763](https://bugzil.la/1855763)).
 Specifically, the disabled properties are:
@@ -918,6 +918,48 @@ Specifically, the disabled properties are:
   </tbody>
 </table>
 
+### UA styles for `<h1>` nested into sectioning elements
+
+`<h1>` headings are no longer decreasing font size when nested into sectioning `<article>`, `<aside>`, `<nav>`, `<section>` elements. These UA styles are no longer relevant due to the changes in the HTML specification [removing the outline algorithm](https://github.com/whatwg/html/pull/7829). This is an experiment to see how this change affects existing web pages and whether it's feasible to remove them by default. ([Firefox bug 1883896](https://bugzil.la/1883896)).
+
+<table>
+  <thead>
+    <tr>
+      <th>Release channel</th>
+      <th>Version added</th>
+      <th>Enabled by default?</th>
+    </tr>
+  </thead>
+  <tbody>
+    <tr>
+      <th>Nightly</th>
+      <td>126</td>
+      <td>Yes</td>
+    </tr>
+    <tr>
+      <th>Developer Edition</th>
+      <td>126</td>
+      <td>No</td>
+    </tr>
+    <tr>
+      <th>Beta</th>
+      <td>126</td>
+      <td>No</td>
+    </tr>
+    <tr>
+      <th>Release</th>
+      <td>126</td>
+      <td>No</td>
+    </tr>
+    <tr>
+      <th>Preference name</th>
+      <td colspan="2">
+        <code>layout.css.h1-in-section-ua-styles.enabled</code>
+      </td>
+    </tr>
+  </tbody>
+</table>
+
 ## SVG
 
 ### SVGPathSeg APIs
diff --git a/files/en-us/mozilla/firefox/releases/125/index.md b/files/en-us/mozilla/firefox/releases/125/index.md
index 079c5153a3122d0..b78090706408cc7 100644
--- a/files/en-us/mozilla/firefox/releases/125/index.md
+++ b/files/en-us/mozilla/firefox/releases/125/index.md
@@ -70,6 +70,10 @@ This article provides information about the changes in Firefox 125 that affect d
 
 These features are newly shipped in Firefox 125 but are disabled by default. To experiment with them, search for the appropriate preference on the `about:config` page and set it to `true`. You can find more such features on the [Experimental features](/en-US/docs/Mozilla/Firefox/Experimental_features) page.
 
+- **UA styles for `<h1>` nested into sectioning elements:** `layout.css.h1-in-section-ua-styles.enabled`.
+
+  `<h1>` headings are no longer decreasing font size when nested into sectioning `<article>`, `<aside>`, `<nav>`, `<section>` elements. These UA styles are no longer relevant due to the changes in the HTML specification [removing the outline algorithm](https://github.com/whatwg/html/pull/7829). This is an experiment to see how this change affects existing web pages and whether it's feasible to remove them by default. ([Firefox bug 1883896](https://bugzil.la/1883896)).
+
 ## Older versions
 
 {{Firefox_for_developers}}

From 3155944397b93a3e129e349a6bf8efedec8c0bc5 Mon Sep 17 00:00:00 2001
From: Vadim Makeev <vmakeev@mozilla.com>
Date: Wed, 10 Apr 2024 12:51:29 +0200
Subject: [PATCH 2/7] Update table and add a note

---
 .../mozilla/firefox/experimental_features/index.md | 14 ++++++++------
 files/en-us/mozilla/firefox/releases/125/index.md  |  4 +++-
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/files/en-us/mozilla/firefox/experimental_features/index.md b/files/en-us/mozilla/firefox/experimental_features/index.md
index d844d53c4ca40a6..bc869c939ab0761 100644
--- a/files/en-us/mozilla/firefox/experimental_features/index.md
+++ b/files/en-us/mozilla/firefox/experimental_features/index.md
@@ -920,35 +920,37 @@ Specifically, the disabled properties are:
 
 ### UA styles for `<h1>` nested into sectioning elements
 
-`<h1>` headings are no longer decreasing font size when nested into sectioning `<article>`, `<aside>`, `<nav>`, `<section>` elements. These UA styles are no longer relevant due to the changes in the HTML specification [removing the outline algorithm](https://github.com/whatwg/html/pull/7829). This is an experiment to see how this change affects existing web pages and whether it's feasible to remove them by default. ([Firefox bug 1883896](https://bugzil.la/1883896)).
+Now `<h1>` headings don't decrease font size when nested into sectioning `<article>`, `<aside>`, `<nav>`, `<section>` elements. These UA styles are no longer relevant due to the changes in the HTML specification [removing the outline algorithm](https://github.com/whatwg/html/pull/7829). This is an experiment to see how this change affects existing web pages and whether it's feasible to remove them by default. ([Firefox bug 1883896](https://bugzil.la/1883896)).
+
+> **Note:** It's a reverse flag: it's set to `false` only in Nightly builds, which removes the UA styles, and to `true` in all other versions, which keeps them.
 
 <table>
   <thead>
     <tr>
       <th>Release channel</th>
       <th>Version added</th>
-      <th>Enabled by default?</th>
+      <th>UA styles removed?</th>
     </tr>
   </thead>
   <tbody>
     <tr>
       <th>Nightly</th>
-      <td>126</td>
+      <td>125</td>
       <td>Yes</td>
     </tr>
     <tr>
       <th>Developer Edition</th>
-      <td>126</td>
+      <td>125</td>
       <td>No</td>
     </tr>
     <tr>
       <th>Beta</th>
-      <td>126</td>
+      <td>125</td>
       <td>No</td>
     </tr>
     <tr>
       <th>Release</th>
-      <td>126</td>
+      <td>125</td>
       <td>No</td>
     </tr>
     <tr>
diff --git a/files/en-us/mozilla/firefox/releases/125/index.md b/files/en-us/mozilla/firefox/releases/125/index.md
index b78090706408cc7..265ebad2a5ff635 100644
--- a/files/en-us/mozilla/firefox/releases/125/index.md
+++ b/files/en-us/mozilla/firefox/releases/125/index.md
@@ -72,7 +72,9 @@ These features are newly shipped in Firefox 125 but are disabled by default. To
 
 - **UA styles for `<h1>` nested into sectioning elements:** `layout.css.h1-in-section-ua-styles.enabled`.
 
-  `<h1>` headings are no longer decreasing font size when nested into sectioning `<article>`, `<aside>`, `<nav>`, `<section>` elements. These UA styles are no longer relevant due to the changes in the HTML specification [removing the outline algorithm](https://github.com/whatwg/html/pull/7829). This is an experiment to see how this change affects existing web pages and whether it's feasible to remove them by default. ([Firefox bug 1883896](https://bugzil.la/1883896)).
+  Now `<h1>` headings don't decrease font size when nested into sectioning `<article>`, `<aside>`, `<nav>`, `<section>` elements. These UA styles are no longer relevant due to the changes in the HTML specification [removing the outline algorithm](https://github.com/whatwg/html/pull/7829). This is an experiment to see how this change affects existing web pages and whether it's feasible to remove them by default. ([Firefox bug 1883896](https://bugzil.la/1883896)).
+
+  > **Note:** It's a reverse flag: it's set to `false` only in Nightly builds, which removes the UA styles, and to `true` in all other versions, which keeps them.
 
 ## Older versions
 

From efda835ba9f8f70ed31ace295a23ff4d03c0fef8 Mon Sep 17 00:00:00 2001
From: Vadim Makeev <hi@pepelsbey.dev>
Date: Thu, 11 Apr 2024 00:44:23 +0200
Subject: [PATCH 3/7] Apply suggestions from code review

Co-authored-by: Dipika Bhattacharya <dipika@foss-community.org>
---
 files/en-us/mozilla/firefox/experimental_features/index.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/files/en-us/mozilla/firefox/experimental_features/index.md b/files/en-us/mozilla/firefox/experimental_features/index.md
index bc869c939ab0761..e420ff444433f78 100644
--- a/files/en-us/mozilla/firefox/experimental_features/index.md
+++ b/files/en-us/mozilla/firefox/experimental_features/index.md
@@ -821,7 +821,7 @@ The [`text-wrap`](/en-US/docs/Web/CSS/text-wrap) CSS property values `balance` a
 
 ### Vendor-prefixed transform properties
 
-The `-moz-` prefixed [CSS transform](/en-US/docs/Web/CSS/CSS_transforms) properties have been disabled in the Nightly release via the `layout.css.prefixes.transforms` preference being set to `false` ([Firefox bug 1855763](https://bugzil.la/1855763)).
+The `-moz-` prefixed [CSS transform](/en-US/docs/Web/CSS/CSS_transforms) properties have been disabled in the Nightly release via the `layout.css.prefixes.transforms` preference being set to `false`. ([Firefox bug 1855763](https://bugzil.la/1855763)).
 Specifically, the disabled properties are:
 
 - `-moz-backface-visibility`
@@ -871,7 +871,7 @@ Specifically, the disabled properties are:
 
 ### Vendor-prefixed transition properties
 
-The `-moz-` prefixed [CSS transitions](/en-US/docs/Web/CSS/CSS_transitions) properties have been disabled in the Nightly release via the `layout.css.prefixes.transitions` preference being set to `false` ([Firefox bug 1855763](https://bugzil.la/1855763)).
+The `-moz-` prefixed [CSS transitions](/en-US/docs/Web/CSS/CSS_transitions) properties have been disabled in the Nightly release via the `layout.css.prefixes.transitions` preference being set to `false`. ([Firefox bug 1855763](https://bugzil.la/1855763)).
 Specifically, the disabled properties are:
 
 - `-moz-transition`
@@ -920,7 +920,7 @@ Specifically, the disabled properties are:
 
 ### UA styles for `<h1>` nested into sectioning elements
 
-Now `<h1>` headings don't decrease font size when nested into sectioning `<article>`, `<aside>`, `<nav>`, `<section>` elements. These UA styles are no longer relevant due to the changes in the HTML specification [removing the outline algorithm](https://github.com/whatwg/html/pull/7829). This is an experiment to see how this change affects existing web pages and whether it's feasible to remove them by default. ([Firefox bug 1883896](https://bugzil.la/1883896)).
+The `<h1>` heading doesn't decrease in font size now when nested within [sectioning elements](/en-US/docs/Web/HTML/Content_categories#sectioning_content), including `<article>`, `<aside>`, `<nav>`, and `<section>`. These UA styles are no longer relevant due to the changes in the HTML specification to [remove the outline algorithm](https://github.com/whatwg/html/pull/7829). ([Firefox bug 1883896](https://bugzil.la/1883896)).
 
 > **Note:** It's a reverse flag: it's set to `false` only in Nightly builds, which removes the UA styles, and to `true` in all other versions, which keeps them.
 

From a27b5400eefa6a41aa56065c6ba7baaf40bae30d Mon Sep 17 00:00:00 2001
From: Vadim Makeev <hi@pepelsbey.dev>
Date: Mon, 15 Apr 2024 11:52:55 +0200
Subject: [PATCH 4/7] Apply suggestions from code review

Co-authored-by: Dipika Bhattacharya <dipika@foss-community.org>
---
 files/en-us/mozilla/firefox/experimental_features/index.md | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/files/en-us/mozilla/firefox/experimental_features/index.md b/files/en-us/mozilla/firefox/experimental_features/index.md
index e420ff444433f78..478205160468578 100644
--- a/files/en-us/mozilla/firefox/experimental_features/index.md
+++ b/files/en-us/mozilla/firefox/experimental_features/index.md
@@ -918,11 +918,11 @@ Specifically, the disabled properties are:
   </tbody>
 </table>
 
-### UA styles for `<h1>` nested into sectioning elements
+### UA style for `<h1>` elements nested in sectioning elements
 
-The `<h1>` heading doesn't decrease in font size now when nested within [sectioning elements](/en-US/docs/Web/HTML/Content_categories#sectioning_content), including `<article>`, `<aside>`, `<nav>`, and `<section>`. These UA styles are no longer relevant due to the changes in the HTML specification to [remove the outline algorithm](https://github.com/whatwg/html/pull/7829). ([Firefox bug 1883896](https://bugzil.la/1883896)).
+The `<h1>` heading doesn't decrease in font size now when nested within [sectioning elements](/en-US/docs/Web/HTML/Content_categories#sectioning_content), including `<article>`, `<aside>`, `<nav>`, and `<section>`. The UA style for `<h1>` nested within sectioning elements is no longer relevant due to the changes in the HTML specification to [remove the outline algorithm](https://github.com/whatwg/html/pull/7829). ([Firefox bug 1883896](https://bugzil.la/1883896)).
 
-> **Note:** It's a reverse flag: it's set to `false` only in Nightly builds, which removes the UA styles, and to `true` in all other versions, which keeps them.
+> **Note:** The preference for this feature works in reverse: it's set to `false` in the Nightly build, which removes the UA styling for headings nested in sectioning elements. It's set to `true` in all other channels, which retains the existing UA styling for the nested headings.
 
 <table>
   <thead>

From 03cd68e6119d9098993e77ca7a7890d1a57679ce Mon Sep 17 00:00:00 2001
From: Vadim Makeev <vmakeev@mozilla.com>
Date: Mon, 15 Apr 2024 12:04:27 +0200
Subject: [PATCH 5/7] Fix heading links

---
 files/en-us/mozilla/firefox/experimental_features/index.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/files/en-us/mozilla/firefox/experimental_features/index.md b/files/en-us/mozilla/firefox/experimental_features/index.md
index 478205160468578..1fe5a939bf5d039 100644
--- a/files/en-us/mozilla/firefox/experimental_features/index.md
+++ b/files/en-us/mozilla/firefox/experimental_features/index.md
@@ -775,7 +775,7 @@ See ([Firefox bug 1855763](https://bugzil.la/1855763) and [Firefox bug 390936](h
   </tbody>
 </table>
 
-To ensure compatibility with these changes, the [Vendor-prefixed transform properties](#vendor-prefixed-transform-properties) and the [Vendor-prefixed transition properties](#vendor-prefixed-transition-properties) are disabled in the Nightly release.
+To ensure compatibility with these changes, the [Vendor-prefixed transform properties](#vendor-prefixed_transform_properties) and the [Vendor-prefixed transition properties](#vendor-prefixed_transition_properties) are disabled in the Nightly release.
 These changes are described in the following sections.
 
 ### text-wrap: balance & stable values

From 8cc6c3ad32a08fa6eedf791fdb254fa9d1dd3f80 Mon Sep 17 00:00:00 2001
From: Vadim Makeev <vmakeev@mozilla.com>
Date: Mon, 15 Apr 2024 12:05:07 +0200
Subject: [PATCH 6/7] Update heading and description

---
 files/en-us/mozilla/firefox/experimental_features/index.md | 6 +++---
 files/en-us/mozilla/firefox/releases/125/index.md          | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/files/en-us/mozilla/firefox/experimental_features/index.md b/files/en-us/mozilla/firefox/experimental_features/index.md
index 1fe5a939bf5d039..3abb7a9d9083012 100644
--- a/files/en-us/mozilla/firefox/experimental_features/index.md
+++ b/files/en-us/mozilla/firefox/experimental_features/index.md
@@ -918,9 +918,9 @@ Specifically, the disabled properties are:
   </tbody>
 </table>
 
-### UA style for `<h1>` elements nested in sectioning elements
+### UA styles for `<h1>` nested in sectioning elements
 
-The `<h1>` heading doesn't decrease in font size now when nested within [sectioning elements](/en-US/docs/Web/HTML/Content_categories#sectioning_content), including `<article>`, `<aside>`, `<nav>`, and `<section>`. The UA style for `<h1>` nested within sectioning elements is no longer relevant due to the changes in the HTML specification to [remove the outline algorithm](https://github.com/whatwg/html/pull/7829). ([Firefox bug 1883896](https://bugzil.la/1883896)).
+The `<h1>` heading doesn't decrease in font size now when nested within [sectioning elements](/en-US/docs/Web/HTML/Content_categories#sectioning_content) `<article>`, `<aside>`, `<nav>`, and `<section>`. The UA styles for `<h1>` nested within sectioning elements are no longer relevant since the outline algorithm [has been removed](https://github.com/whatwg/html/pull/7829) from the HTML specification. ([Firefox bug 1883896](https://bugzil.la/1883896)).
 
 > **Note:** The preference for this feature works in reverse: it's set to `false` in the Nightly build, which removes the UA styling for headings nested in sectioning elements. It's set to `true` in all other channels, which retains the existing UA styling for the nested headings.
 
@@ -929,7 +929,7 @@ The `<h1>` heading doesn't decrease in font size now when nested within [section
     <tr>
       <th>Release channel</th>
       <th>Version added</th>
-      <th>UA styles removed?</th>
+      <th>Enabled by default?</th>
     </tr>
   </thead>
   <tbody>
diff --git a/files/en-us/mozilla/firefox/releases/125/index.md b/files/en-us/mozilla/firefox/releases/125/index.md
index 265ebad2a5ff635..9b378fcb63d0255 100644
--- a/files/en-us/mozilla/firefox/releases/125/index.md
+++ b/files/en-us/mozilla/firefox/releases/125/index.md
@@ -72,9 +72,9 @@ These features are newly shipped in Firefox 125 but are disabled by default. To
 
 - **UA styles for `<h1>` nested into sectioning elements:** `layout.css.h1-in-section-ua-styles.enabled`.
 
-  Now `<h1>` headings don't decrease font size when nested into sectioning `<article>`, `<aside>`, `<nav>`, `<section>` elements. These UA styles are no longer relevant due to the changes in the HTML specification [removing the outline algorithm](https://github.com/whatwg/html/pull/7829). This is an experiment to see how this change affects existing web pages and whether it's feasible to remove them by default. ([Firefox bug 1883896](https://bugzil.la/1883896)).
+  The `<h1>` heading doesn't decrease in font size now when nested within [sectioning elements](/en-US/docs/Web/HTML/Content_categories#sectioning_content) `<article>`, `<aside>`, `<nav>`, and `<section>`. The UA styles for `<h1>` nested within sectioning elements are no longer relevant since the outline algorithm [has been removed](https://github.com/whatwg/html/pull/7829) from the HTML specification. ([Firefox bug 1883896](https://bugzil.la/1883896)).
 
-  > **Note:** It's a reverse flag: it's set to `false` only in Nightly builds, which removes the UA styles, and to `true` in all other versions, which keeps them.
+  > **Note:** The preference for this feature works in reverse: it's set to `false` in the Nightly build, which removes the UA styling for headings nested in sectioning elements. It's set to `true` in all other channels, which retains the existing UA styling for the nested headings.
 
 ## Older versions
 

From e7f0a5a1c85a8dbeee98883d868c732b99124862 Mon Sep 17 00:00:00 2001
From: Vadim Makeev <vmakeev@mozilla.com>
Date: Tue, 16 Apr 2024 12:09:41 +0200
Subject: [PATCH 7/7] Reversing flags

---
 .../en-us/mozilla/firefox/experimental_features/index.md  | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/files/en-us/mozilla/firefox/experimental_features/index.md b/files/en-us/mozilla/firefox/experimental_features/index.md
index 88d3d41dcc9bcd5..e83e8e6d0d1d752 100644
--- a/files/en-us/mozilla/firefox/experimental_features/index.md
+++ b/files/en-us/mozilla/firefox/experimental_features/index.md
@@ -936,22 +936,22 @@ The `<h1>` heading doesn't decrease in font size now when nested within [section
     <tr>
       <th>Nightly</th>
       <td>125</td>
-      <td>Yes</td>
+      <td>No</td>
     </tr>
     <tr>
       <th>Developer Edition</th>
       <td>125</td>
-      <td>No</td>
+      <td>Yes</td>
     </tr>
     <tr>
       <th>Beta</th>
       <td>125</td>
-      <td>No</td>
+      <td>Yes</td>
     </tr>
     <tr>
       <th>Release</th>
       <td>125</td>
-      <td>No</td>
+      <td>Yes</td>
     </tr>
     <tr>
       <th>Preference name</th>