# Fix mobile divination tutorial overlay

## Goal

Fix the mobile web tutorial overlay on manual and auto divination pages so spotlight targets, tooltip placement, arrow direction, and overlay shadow match the intended mobile UX.

## What I already know

* User reports mobile tutorial has an overly large dark/shadowed area.
* Step 3 should highlight the six yao area, not only the coin area. If the full coin + yao area is too large, highlight only the six yao rows and exclude the coins.
* Step 4 tooltip arrow should point down toward the spotlighted "start divination" button.
* Step 4 tooltip currently overlaps the spotlight region.
* Affected files are `web/src/components/ManualDivinationPage.tsx` and `web/src/components/AutoDivinationPage.tsx`.

## Assumptions

* Keep desktop behavior visually equivalent unless the existing code already uses a different desktop target.
* Mobile behavior is the priority for this task.
* No backend or protocol changes are needed.

## Requirements

* Mobile step 3 highlights the six yao rows/panel area and excludes the coin selector.
* Mobile step 4 places the tooltip above the submit/start button with enough gap to avoid overlap.
* Mobile step 4 arrow points downward toward the spotlighted button.
* Remove the excessive/double-shadow appearance caused by overlapping dimming strategies.
* Apply the same behavior to manual and auto divination tutorial overlays.

## Acceptance Criteria

* [x] In mobile viewport, manual step 3 spotlight excludes the coin selector.
* [x] In mobile viewport, auto step 3 spotlight excludes the coin selector.
* [x] In mobile viewport, manual step 4 tooltip does not overlap the highlighted submit button and arrow points down.
* [x] In mobile viewport, auto step 4 tooltip does not overlap the highlighted submit button and arrow points down.
* [x] Overlay dimming is visually consistent without large unintended dark blocks.

## Definition of Done

* Local browser verification at a phone-sized viewport.
* `git diff --check` passes.
* Build/typecheck status documented if blocked by existing project configuration.

## Out of Scope

* Redesigning the tutorial copy.
* Changing tutorial persistence/profile settings behavior.
* Backend auth/session changes.

## Technical Notes

* Web spec applies: `.trellis/spec/web/index.md`.
* Existing mobile threshold uses `window.innerWidth < 1280`.
* App shell scroll container is the main vertical scrolling region.