WIP PWA for Grain
docs: add alt overlay scroll fix plan
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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docs/plans/2026-01-04-alt-overlay-scroll-fix.md
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docs/plans/2026-01-04-alt-overlay-scroll-fix.md
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# Alt Text Overlay Scroll Fix
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> **For Claude:** REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task.
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**Goal:** Fix alt text overlay position drifting when page scrolls by moving overlay rendering from the badge to the carousel.
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**Architecture:** Move overlay from `grain-alt-badge` (which uses `position: fixed` with JS positioning) to `grain-image-carousel` (which renders it inside the slide with `position: absolute; inset: 0`). The badge becomes a simple button that emits an event.
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**Tech Stack:** Lit, Web Components, CSS
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---
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### Task 1: Simplify grain-alt-badge to emit event
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**Files:**
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- Modify: `src/components/atoms/grain-alt-badge.js`
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**Step 1: Remove overlay state and scroll listener logic**
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Replace the entire file with:
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```js
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import { LitElement, html, css } from 'lit';
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export class GrainAltBadge extends LitElement {
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static properties = {
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alt: { type: String }
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};
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static styles = css`
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:host {
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position: absolute;
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bottom: 8px;
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right: 8px;
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z-index: 2;
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}
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.badge {
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background: rgba(0, 0, 0, 0.7);
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color: white;
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font-size: 10px;
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font-weight: 600;
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padding: 2px 4px;
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border-radius: 4px;
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cursor: pointer;
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user-select: none;
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border: none;
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font-family: inherit;
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}
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.badge:hover {
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background: rgba(0, 0, 0, 0.85);
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}
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.badge:focus {
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outline: 2px solid white;
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outline-offset: 1px;
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}
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`;
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constructor() {
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super();
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this.alt = '';
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}
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#handleClick(e) {
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e.stopPropagation();
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this.dispatchEvent(new CustomEvent('alt-click', {
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bubbles: true,
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composed: true,
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detail: { alt: this.alt }
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}));
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}
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render() {
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if (!this.alt) return null;
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return html`
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<button class="badge" @click=${this.#handleClick} aria-label="View image description">ALT</button>
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`;
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}
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}
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customElements.define('grain-alt-badge', GrainAltBadge);
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```
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**Step 2: Verify badge still renders**
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Run the app, navigate to a gallery with alt text, confirm "ALT" button appears.
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---
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### Task 2: Add overlay state and styles to grain-image-carousel
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**Files:**
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- Modify: `src/components/organisms/grain-image-carousel.js`
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**Step 1: Add `_activeAltIndex` state property**
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In `static properties`, add:
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```js
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static properties = {
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photos: { type: Array },
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rkey: { type: String },
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_currentIndex: { state: true },
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_activeAltIndex: { state: true }
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};
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```
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**Step 2: Initialize state in constructor**
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Add to constructor:
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```js
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this._activeAltIndex = null;
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```
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**Step 3: Add overlay styles**
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Add to `static styles` (after `.nav-arrow-right`):
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```css
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.alt-overlay {
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position: absolute;
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inset: 0;
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background: rgba(0, 0, 0, 0.75);
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color: white;
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padding: 16px;
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font-size: 14px;
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line-height: 1.5;
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overflow-y: auto;
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display: flex;
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align-items: center;
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justify-content: center;
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text-align: center;
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box-sizing: border-box;
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z-index: 3;
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cursor: pointer;
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}
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```
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---
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### Task 3: Add overlay event handlers to carousel
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**Files:**
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- Modify: `src/components/organisms/grain-image-carousel.js`
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**Step 1: Add handler for alt-click event**
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Add method:
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```js
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#handleAltClick(e, index) {
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e.stopPropagation();
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this._activeAltIndex = index;
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}
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```
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**Step 2: Add handler for overlay click (dismiss)**
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Add method:
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```js
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#handleOverlayClick(e) {
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e.stopPropagation();
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this._activeAltIndex = null;
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}
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```
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**Step 3: Dismiss overlay on slide change**
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Modify `#handleScroll` to clear overlay when swiping:
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```js
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#handleScroll(e) {
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const carousel = e.target;
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const index = Math.round(carousel.scrollLeft / carousel.offsetWidth);
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if (index !== this._currentIndex) {
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this._currentIndex = index;
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this._activeAltIndex = null;
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}
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}
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```
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---
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### Task 4: Render overlay in slide template
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**Files:**
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- Modify: `src/components/organisms/grain-image-carousel.js`
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**Step 1: Update slide template in render()**
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Replace the slide mapping (lines 153-162) with:
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```js
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${this.photos.map((photo, index) => html`
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<div class="slide ${hasPortrait ? 'centered' : ''}">
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<grain-image
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src=${this.#shouldLoad(index) ? photo.url : ''}
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alt=${photo.alt || ''}
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aspectRatio=${photo.aspectRatio || 1}
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style=${index === 0 && this.rkey ? `view-transition-name: gallery-hero-${this.rkey};` : ''}
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></grain-image>
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${photo.alt ? html`
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<grain-alt-badge
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.alt=${photo.alt}
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@alt-click=${(e) => this.#handleAltClick(e, index)}
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></grain-alt-badge>
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` : ''}
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${this._activeAltIndex === index ? html`
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<div class="alt-overlay" @click=${this.#handleOverlayClick}>
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${photo.alt}
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</div>
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` : ''}
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</div>
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`)}
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```
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---
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### Task 5: Manual testing
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**Step 1: Test overlay appears correctly**
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1. Navigate to a gallery with alt text
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2. Click "ALT" button
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3. Confirm overlay appears covering the image
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**Step 2: Test overlay dismisses on click**
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1. With overlay open, click the overlay
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2. Confirm overlay closes
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**Step 3: Test overlay dismisses on swipe**
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1. Open alt overlay on first image
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2. Swipe to second image
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3. Confirm overlay closes
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**Step 4: Test scroll behavior (the bug fix)**
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1. Open alt overlay
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2. Scroll the page up/down
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3. Confirm overlay stays attached to the image (doesn't drift)
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---
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### Task 6: Commit
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```bash
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git add src/components/atoms/grain-alt-badge.js src/components/organisms/grain-image-carousel.js
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git commit -m "fix: alt text overlay stays attached on page scroll
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Move overlay rendering from grain-alt-badge to grain-image-carousel.
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The overlay now uses position:absolute within the slide instead of
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position:fixed with JS positioning, so it naturally scrolls with content."
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```