diff --git a/docs/26-incident-2026-05-09-page-unresponsive-and-playback.md b/docs/26-incident-2026-05-09-page-unresponsive-and-playback.md
index f9fde99..b8ff56a 100644
--- a/docs/26-incident-2026-05-09-page-unresponsive-and-playback.md
+++ b/docs/26-incident-2026-05-09-page-unresponsive-and-playback.md
@@ -1304,6 +1304,59 @@ that the device profile doesn't DirectPlay).
 **Repo commit:** `web-overrides/index.html` updated under git so the
 repo state matches the deployed file (no drift).
 
+### INC5 scrollbar grey strip (2026-05-09 ~02:05 UTC)
+
+**Symptom.** Owner reported thin grey horizontal strip at very bottom
+of page on https://arrflix.s8n.ru/web/#/home.html when scrolled. Strip
+about 15px tall, full-width. Should be black to match ARRFLIX dark
+theme.
+
+**Root cause.** Chrome native scrollbar default track color = grey
+(`#f5f5f5`-ish on light, mid-grey on dark sites). Visible as the
+bottom-row scrollbar gutter even when no horizontal overflow exists,
+because Chrome renders the gutter under the page's `overflow: scroll`
+container. BLACK-PASS rules covered every visible content surface but
+missed browser native UI chrome. `::-webkit-scrollbar` pseudo-elements
+are the only path to style it.
+
+**Fix.** Add `::-webkit-scrollbar*` rules to `branding.xml` CustomCss
+painting track `#000000`, thumb `#2a2a2a` (lighter grey for visibility
+on hover `#3a3a3a`), corner `#000000`, plus `scrollbar-color` for
+Firefox. Apply server-wide so all scrollbars (page, carousels, dialogs)
+match.
+
+**Patch (idempotent, marked INC5):**
+
+```css
+*::-webkit-scrollbar {
+  background: #000000 !important;
+  width: 10px;
+  height: 10px;
+}
+*::-webkit-scrollbar-track    { background: #000000 !important; }
+*::-webkit-scrollbar-thumb    {
+  background: #2a2a2a !important;
+  border-radius: 5px;
+}
+*::-webkit-scrollbar-thumb:hover { background: #3a3a3a !important; }
+*::-webkit-scrollbar-corner   { background: #000000 !important; }
+* { scrollbar-color: #2a2a2a #000000; }
+html, body { scrollbar-color: #2a2a2a #000000; }
+```
+
+**Verified.** Applied to `/home/docker/jellyfin/config/config/branding.xml`
+on prod, `docker restart jellyfin`. Owner-side hard-reload removes grey
+strip.
+
+**Lesson learned.** BLACK-PASS rules covered all visible content
+surfaces but missed browser native UI chrome. When designing a
+fully-black theme, audit scrollbars + form controls + native
+context menus + select dropdowns separately — they bypass site CSS
+and use UA defaults unless explicitly styled.
+
+**Repo:** patch added to `bin/apply-26-incident-fixes.sh` so re-applies
+include INC5 scrollbar.
+
 ### INC5 MNS playback verify (post-fix end-to-end test)
 
 Closes the loop on Iteration-3 INC5 fixes (AV1 source re-encode +