From 6a31814900321e9278511ceb1fb5cfecd1bdb2b6 Mon Sep 17 00:00:00 2001
From: "alexei.dolgolyov" <dolgolyov.alexei@gmail.com>
Date: Wed, 18 Mar 2026 11:39:53 +0300
Subject: [PATCH] Fix scroll position reset when closing modals

- Use { behavior: 'instant' } in unlockBody scrollTo to override
  CSS scroll-behavior: smooth on html element
- Use { preventScroll: true } on focus() restore in Modal.forceClose
- Add overflow-y: scroll to body.modal-open to prevent scrollbar shift

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 server/src/wled_controller/static/css/base.css     | 1 +
 server/src/wled_controller/static/js/core/modal.js | 2 +-
 server/src/wled_controller/static/js/core/ui.js    | 2 +-
 3 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/server/src/wled_controller/static/css/base.css b/server/src/wled_controller/static/css/base.css
index 4e9996b..799f48d 100644
--- a/server/src/wled_controller/static/css/base.css
+++ b/server/src/wled_controller/static/css/base.css
@@ -93,6 +93,7 @@ body {
 body.modal-open {
     position: fixed;
     width: 100%;
+    overflow-y: scroll; /* keep scrollbar gutter to prevent layout shift */
 }
 
 /* ── Ambient animated background ── */
diff --git a/server/src/wled_controller/static/js/core/modal.js b/server/src/wled_controller/static/js/core/modal.js
index 47bd1eb..6b5c7a6 100644
--- a/server/src/wled_controller/static/js/core/modal.js
+++ b/server/src/wled_controller/static/js/core/modal.js
@@ -43,7 +43,7 @@ export class Modal {
         this.onForceClose();
         Modal._stack = Modal._stack.filter(m => m !== this);
         if (this._previousFocus && typeof this._previousFocus.focus === 'function') {
-            this._previousFocus.focus();
+            this._previousFocus.focus({ preventScroll: true });
             this._previousFocus = null;
         }
     }
diff --git a/server/src/wled_controller/static/js/core/ui.js b/server/src/wled_controller/static/js/core/ui.js
index 4243f19..719cc5f 100644
--- a/server/src/wled_controller/static/js/core/ui.js
+++ b/server/src/wled_controller/static/js/core/ui.js
@@ -84,7 +84,7 @@ export function unlockBody() {
     if (_lockCount === 0) {
         document.body.classList.remove('modal-open');
         document.body.style.top = '';
-        window.scrollTo(0, _savedScrollY);
+        window.scrollTo({ top: _savedScrollY, behavior: 'instant' });
     }
 }