diff --git a/wiki/_master-index.md b/wiki/_master-index.md
index c924781..460d0e5 100644
--- a/wiki/_master-index.md
+++ b/wiki/_master-index.md
@@ -23,7 +23,7 @@ This 3-hop pattern works for hundreds of articles without vector search.
| [[wiki/tech-patterns/_index\|tech-patterns/]] | Recurring tech stacks: FastAPI, React/Vite, Next.js, Azure AD, AI, Box, One2Edit, Redis/Celery, cost-tracker, OMG API | 29 |
| [[wiki/architecture/_index\|architecture/]] | Cross-cutting architectural patterns: Docker Compose, multi-agent AI, GCP timeout, RAG, hotfolder, optical-dev deploy, cost-tracker, new-project checklist, troubleshooting playbooks, ADR log, Cloud Run Jobs | 11 |
| [[wiki/client-knowledge/_index\|client-knowledge/]] | Per-client notes for Ford, H&M, L'Oréal, Barclays, Ferrero, 3M, BAIC | 7 |
-| [[wiki/concepts/_index\|concepts/]] | Atomic knowledge extracted from Claude Code sessions | 191 |
+| [[wiki/concepts/_index\|concepts/]] | Atomic knowledge extracted from Claude Code sessions | 192 |
| [[wiki/connections/_index\|connections/]] | Cross-cutting insights linking 2+ concepts: FastAPI+Azure AD+Docker trinity, AI→cost-tracker, Apache+Vite basePath, GCP→REST polling, Box+hotfolder, Docker DNS+AdGuard, Celery prefork×faster_whisper memory stacking | 10 |
| [[wiki/qa/_index\|qa/]] | Filed answers to queries (saved with `--file-back`) | 0 |
| [[wiki/homelab/_index\|homelab/]] | Self-hosted infra: Proxmox install, IOMMU/PCI passthrough, hypervisor setup, budget builds, HP Elitedesk G3, Homarr API + Apps + Boards + Certificates + Integrations + Settings + Tasks + AdGuard + Clock + Docker Stats + Docker Integration + Download Client + Firewall + Proxmox Integration + Radarr + Readarr + Sonarr + Bookmarks + Calendar + Icons + App Widget + Weather + GitHub + Nextcloud + qBittorrent + RSS Feed + Speedtest Tracker + System Health Monitoring + System Resources + Services Map + Media Stack | 43 |
diff --git a/wiki/concepts/_index.md b/wiki/concepts/_index.md
index 1534299..bc8c8db 100644
--- a/wiki/concepts/_index.md
+++ b/wiki/concepts/_index.md
@@ -212,5 +212,6 @@
| [[wiki/concepts/nextjs16-lint-command-removed\|Next.js 16 — next lint Command Removed]] | `next lint` is removed in Next.js 16. Running it produces: | daily/2026-05-10.md | 2026-05-10 |
| [[wiki/concepts/overflow-hidden-clips-positioned-children\|CSS overflow-hidden Clips Absolutely-Positioned Children]] | `overflow: hidden` clips all descendants including absolute/fixed children regardless of z-index — move interactive elements outside the container | daily/2026-05-10.md | 2026-05-10 |
| [[wiki/concepts/react-state-playwright-css-hover\|React useState Dropdown — CSS group-hover vs useState for Playwright]] | Playwright `hover()` on a trigger element does not reliably open a React dropdown that uses `useStat | daily/2026-05-10.md | 2026-05-10 |
+| [[wiki/concepts/overflow-hidden-clips-absolute-children\|overflow:hidden Clips Absolute/Fixed Children Regardless of z-index]] | `overflow: hidden` on a parent element **clips all descendant content at its boundary** — including | daily/2026-05-10.md | 2026-05-10 |
diff --git a/wiki/concepts/overflow-hidden-clips-absolute-children.md b/wiki/concepts/overflow-hidden-clips-absolute-children.md
new file mode 100644
index 0000000..4ddab2a
--- /dev/null
+++ b/wiki/concepts/overflow-hidden-clips-absolute-children.md
@@ -0,0 +1,65 @@
+---
+title: "overflow:hidden Clips Absolute/Fixed Children Regardless of z-index"
+source: daily/2026-05-10.md
+updated: 2026-05-10
+tags: [css, overflow, z-index, positioning, dropdown]
+---
+
+# `overflow: hidden` Clips Absolute/Fixed Children Regardless of z-index
+
+## Rule
+
+`overflow: hidden` on a parent element **clips all descendant content at its boundary** — including absolutely-positioned children — regardless of their `z-index` value.
+
+## Symptom
+
+A dropdown or tooltip is visible in DevTools (correct dimensions, correct position) but **not visible in the viewport**. The element is rendered but clipped by an ancestor's overflow boundary.
+
+Confusion arises because developers reach for `z-index` to fix "element hidden behind something" problems, but overflow clipping is a separate mechanism from stacking order.
+
+## Diagnosis
+
+1. Open DevTools → Elements
+2. Inspect the dropdown — it shows correct geometry
+3. Walk up the DOM ancestors: find the element with `overflow: hidden` or `overflow-x: hidden`
+
+Common culprits: frosted-glass header containers, card components, scroll areas.
+
+## Fix
+
+**Option A — Remove `overflow-hidden` from the container:**
+
+```html
+
+
+
+
+
+```
+
+**Option B — Move the dropdown outside the overflow container:**
+
+```html
+
+
+...
+```
+
+## DOM Ordering and z-index
+
+An element **earlier in the DOM** within the same stacking context can render under a later sibling even with higher z-index. When debugging z-index problems:
+
+- Confirm `position` is set (z-index only applies to positioned elements)
+- Check for stacking context on ancestors (`transform`, `opacity < 1`, `filter`, `will-change`)
+
+## Common Pattern — Glass Header
+
+Frosted-glass headers use `overflow: hidden` to clip the blur effect to the header box. If the navigation has a dropdown, the dropdown **must** be placed outside the header ``, not inside it.
diff --git a/wiki/log.md b/wiki/log.md
index 491a908..2f989ea 100644
--- a/wiki/log.md
+++ b/wiki/log.md
@@ -335,3 +335,9 @@
- Articles created: [[wiki/concepts/apache-proxypass-include-files-ignored]], [[wiki/concepts/cookie-domain-migration-auth-loop]]
- Articles updated: [[wiki/client-knowledge/ford]] (service path, GPAS naming, SSH alias), [[wiki/architecture/cloud-run-jobs-celery]] (USE_CELERY_FALLBACK, optical-dev override), [[wiki/architecture/optical-dev-server-deploy]] (ProxyPass include limitation)
- Index updates: [[wiki/concepts/_index]] (73→75); [[wiki/_master-index]] (concepts 73→75)
+
+## [2026-05-10T21:00:00+03:00] compile | 2026-05-10.md
+- Source: daily/2026-05-10.md
+- Sessions: kvytky/shumiland Next.js+Payload CMS, banner-tool
+- Articles created: [[wiki/concepts/payload-cms-root-layout-requirement]], [[wiki/concepts/payload-cms-node26-esm-workaround]], [[wiki/concepts/overflow-hidden-clips-absolute-children]], [[wiki/concepts/pydantic-exclude-none-null-clearing-conflict]], [[wiki/concepts/css-marquee-animation-gpu-pattern]], [[wiki/concepts/css-animation-js-scroll-conflict]], [[wiki/concepts/nextjs16-lint-command-removed]], [[wiki/concepts/figma-mcp-oauth-reconnect-restart]], [[wiki/concepts/react-state-playwright-css-hover]]
+- Index updates: [[wiki/concepts/_index]] (187→196); [[wiki/_master-index]] (concepts 187→196)