From 31d939e9caeb93de5f8a1275bf618acedb2410bb Mon Sep 17 00:00:00 2001
From: Sebastien Ahkrin <30870051+Sebastien-Ahkrin@users.noreply.github.com>
Date: Tue, 11 Aug 2026 21:09:44 +0200
Subject: [PATCH 1/3] fix(prevent-link-loss): mount banner outside the fieldset

Closes: https://github.com/refined-github/refined-github/issues/9955
---
 source/features/prevent-link-loss.tsx | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/source/features/prevent-link-loss.tsx b/source/features/prevent-link-loss.tsx
index d186dce9329e..15b2fc7574a7 100644
--- a/source/features/prevent-link-loss.tsx
+++ b/source/features/prevent-link-loss.tsx
@@ -14,12 +14,11 @@ function attach(field: HTMLTextAreaElement): void {
 		// Editing PR body
 		'.CommentBox',
 	], field);
-	mount(Banner, {
-		target,
-		props: {
-			field,
-		},
-	});
+
+	const wrapper = document.createElement('div');
+	target.after(wrapper);
+
+	mount(Banner, { target: wrapper, props: { field } });
 }
 
 function init(signal: AbortSignal): void {

From f4585bbf4abf1c03eb7bad883dc1d1218b282aa9 Mon Sep 17 00:00:00 2001
From: Sebastien Ahkrin <30870051+Sebastien-Ahkrin@users.noreply.github.com>
Date: Tue, 11 Aug 2026 21:41:51 +0200
Subject: [PATCH 2/3] refactor: do not create a new div

---
 source/features/prevent-link-loss.tsx | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/source/features/prevent-link-loss.tsx b/source/features/prevent-link-loss.tsx
index 15b2fc7574a7..b99f860ad8d5 100644
--- a/source/features/prevent-link-loss.tsx
+++ b/source/features/prevent-link-loss.tsx
@@ -15,10 +15,10 @@ function attach(field: HTMLTextAreaElement): void {
 		'.CommentBox',
 	], field);
 
-	const wrapper = document.createElement('div');
-	target.after(wrapper);
-
-	mount(Banner, { target: wrapper, props: { field } });
+	mount(Banner, {
+		target: target.parentElement!,
+		anchor: target.nextSibling ?? undefined, props: {field},
+	});
 }
 
 function init(signal: AbortSignal): void {

From de823dac37f46d605b520a7648cf6b76d992a08c Mon Sep 17 00:00:00 2001
From: Sebastien Ahkrin <30870051+Sebastien-Ahkrin@users.noreply.github.com>
Date: Wed, 12 Aug 2026 00:16:46 +0200
Subject: [PATCH 3/3] fix: mount banner outside fieldset only on new markdown
 editor

---
 source/features/prevent-link-loss.tsx | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/source/features/prevent-link-loss.tsx b/source/features/prevent-link-loss.tsx
index b99f860ad8d5..80ea544ccaee 100644
--- a/source/features/prevent-link-loss.tsx
+++ b/source/features/prevent-link-loss.tsx
@@ -15,9 +15,23 @@ function attach(field: HTMLTextAreaElement): void {
 		'.CommentBox',
 	], field);
 
+	if (target instanceof HTMLFieldSetElement) {
+		// On the new Markdown editor mounting a child directly inside the `fieldset` collapses
+		// its height to 0, hiding the textarea entirely. Mounting as a sibling instead avoids the issues.
+		// https://github.com/refined-github/refined-github/issues/9955
+		mount(Banner, {
+			target: target.parentElement!,
+			anchor: target.nextSibling ?? undefined, props: {field},
+		});
+
+		return;
+	}
+
+	// Old Markdown editor doesn't have this bug, so we can keep mounting inside it.
+	// This also preserve the extra margin for old views (PR)
 	mount(Banner, {
-		target: target.parentElement!,
-		anchor: target.nextSibling ?? undefined, props: {field},
+		target,
+		props: {field},
 	});
 }