diff --git a/skill/scripts/live-browser.js b/skill/scripts/live-browser.js
index 3cbdaceb1..bc71d8e5a 100644
--- a/skill/scripts/live-browser.js
+++ b/skill/scripts/live-browser.js
@@ -152,6 +152,7 @@
   let scrollLockTargetY = null;
   let scrollLockRaf = null;
   let scrollLockAbort = null;
+  const SCROLL_ANCHOR_LOCK_ID = 'impeccable-scroll-anchor-lock';
 
   // Dedicated key for scroll position - SEPARATE from LS_KEY so that
   // saveSession's state updates don't clobber a carefully-captured scrollY.
@@ -5815,10 +5816,22 @@
 
     try { history.scrollRestoration = 'manual'; } catch {}
 
-    const prevHtmlAnchor = document.documentElement.style.overflowAnchor;
-    const prevBodyAnchor = document.body.style.overflowAnchor;
-    document.documentElement.style.overflowAnchor = 'none';
-    document.body.style.overflowAnchor = 'none';
+    // Suppress the browser's scroll-anchoring on the scroll root so it can't
+    // fight our manual scroll correction. Apply this as a stylesheet rule, not
+    // as inline `style` on <html>/<body>: those elements are server-rendered by
+    // frameworks like Next.js App Router, and mutating their inline style makes
+    // React 19 report a hydration mismatch on the next Fast-Refresh re-render.
+    // A <style> rule has the same computed effect without touching any hydrated
+    // element's attributes. Like the inline version, it is recreated on every
+    // startScrollLock call, so reload survival (driven by the persisted scroll
+    // key) is unaffected.
+    let anchorLockStyle = document.getElementById(SCROLL_ANCHOR_LOCK_ID);
+    if (!anchorLockStyle) {
+      anchorLockStyle = document.createElement('style');
+      anchorLockStyle.id = SCROLL_ANCHOR_LOCK_ID;
+      anchorLockStyle.textContent = 'html,body{overflow-anchor:none !important;}';
+      (document.head || document.documentElement).appendChild(anchorLockStyle);
+    }
 
     const correct = (why) => {
       scrollLockRaf = null;
@@ -5853,8 +5866,7 @@
 
     scrollLockAbort = new AbortController();
     scrollLockAbort.signal.addEventListener('abort', () => {
-      document.documentElement.style.overflowAnchor = prevHtmlAnchor;
-      document.body.style.overflowAnchor = prevBodyAnchor;
+      document.getElementById(SCROLL_ANCHOR_LOCK_ID)?.remove();
     }, { once: true });
     const sig = { signal: scrollLockAbort.signal };
     // Track whether the most recent scroll came from a user gesture. We
diff --git a/tests/live-browser-regression.test.mjs b/tests/live-browser-regression.test.mjs
index 6d15346d3..9a91ccddf 100644
--- a/tests/live-browser-regression.test.mjs
+++ b/tests/live-browser-regression.test.mjs
@@ -280,6 +280,44 @@ describe('live-browser.js regression guards', () => {
     );
   });
 
+  it('suppresses scroll anchoring via a stylesheet rule, not inline html/body style', () => {
+    // The scroll lock disables the browser's scroll-anchoring on the scroll
+    // root so it can't fight our manual scroll correction. Doing that by
+    // mutating `document.documentElement.style` / `document.body.style`
+    // inline makes React 19 report a hydration mismatch on the next
+    // Fast-Refresh re-render: <html>/<body> are server-rendered by frameworks
+    // like Next.js App Router, so a client-only inline `style` the server HTML
+    // never emitted trips "a tree hydrated but some attributes ... didn't
+    // match." That surfaced as a console.error and failed the
+    // nextjs-app-router live-e2e fixture's expectConsoleClean probe. The fix
+    // injects a <style> rule with the same computed effect instead.
+    assert.doesNotMatch(
+      SOURCE,
+      /document\.documentElement\.style\.overflowAnchor\s*=/,
+      'event=live_browser.scroll_anchor_hydration actor=browser operation=start_scroll_lock risk=react19_hydration_mismatch_on_next_app_router expected=stylesheet_rule actual=inline_style_on_html',
+    );
+    assert.doesNotMatch(
+      SOURCE,
+      /document\.body\.style\.overflowAnchor\s*=/,
+      'scroll lock must not mutate <body> inline overflowAnchor — it desyncs server/client hydration on SSR frameworks',
+    );
+    assert.match(
+      SOURCE,
+      /const SCROLL_ANCHOR_LOCK_ID = 'impeccable-scroll-anchor-lock';/,
+      'the anchor-suppression style needs a stable id constant so it can be created and removed by id',
+    );
+    assert.match(
+      SOURCE,
+      /document\.getElementById\(SCROLL_ANCHOR_LOCK_ID\);[\s\S]{0,400}?createElement\('style'\)[\s\S]{0,400}?overflow-anchor:none[\s\S]{0,400}?\(document\.head \|\| document\.documentElement\)\.appendChild/,
+      'the scroll lock must suppress scroll anchoring with an injected <style> rule keyed by SCROLL_ANCHOR_LOCK_ID',
+    );
+    assert.match(
+      SOURCE,
+      /scrollLockAbort\.signal\.addEventListener\('abort', \(\) => \{\s*document\.getElementById\(SCROLL_ANCHOR_LOCK_ID\)\?\.remove\(\);/,
+      'stopping the scroll lock must remove the injected anchor-suppression <style> so it never outlives the session',
+    );
+  });
+
   it('global bar includes expandable page chat affordance', () => {
     assert.match(
       SOURCE,
