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+# Back-to-Top Button Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Add a fixed bottom-right back-to-top button that appears after 33% scroll depth on article/single pages, with slide-up animation, full accessibility, and hacker-theme styling.
+
+**Architecture:** A new `back-to-top.html` partial uses inline Alpine.js `x-data` with `@scroll.window` to track scroll depth; the button is conditionally included in `baseof.html` on `.Kind "page"` pages (same condition as reading progress bar). CSS lives in a new `.back-to-top` component class in `main.css`.
+
+**Tech Stack:** Hugo partials, Alpine.js 3.x (inline x-data), Tailwind CSS (@apply), Feather Icons (chevron-up inlined SVG)
+
+---
+
+## File Map
+
+| Action | File | Responsibility |
+|---|---|---|
+| Create | `themes/danix-xyz-hacker/layouts/partials/back-to-top.html` | Button markup + Alpine logic |
+| Modify | `themes/danix-xyz-hacker/assets/css/main.css` | `.back-to-top` component class |
+| Modify | `themes/danix-xyz-hacker/layouts/_default/baseof.html` | Include partial on `.Kind "page"` |
+| Modify | `themes/danix-xyz-hacker/i18n/en.yaml` | `back_to_top` key |
+| Modify | `themes/danix-xyz-hacker/i18n/it.yaml` | `back_to_top` key (Italian) |
+
+---
+
+### Task 1: Add `.back-to-top` CSS component class
+
+**Files:**
+- Modify: `themes/danix-xyz-hacker/assets/css/main.css` (append inside `@layer components`, after `.toast-container`)
+
+- [ ] **Step 1: Open `main.css` and locate the end of `@layer components`**
+
+Find the closing `}` of `@layer components`. It ends around line 1165 (after `.tooltip-text`). Add the new class block just before that closing brace.
+
+- [ ] **Step 2: Add the `.back-to-top` class**
+
+```css
+  /* Back to top button */
+  .back-to-top {
+    @apply fixed bottom-6 right-6 z-40 w-11 h-11 rounded-full flex items-center justify-content-center;
+    background: var(--accent);
+    box-shadow: 0 0 12px rgba(168, 85, 247, 0.4);
+    transition: background 200ms ease, box-shadow 200ms ease;
+    color: #fff;
+  }
+  .back-to-top:hover {
+    background: #9333ea;
+    box-shadow: 0 0 20px var(--accent);
+  }
+  .back-to-top:focus-visible {
+    outline: 2px solid var(--accent);
+    outline-offset: 2px;
+  }
+```
+
+- [ ] **Step 3: Rebuild CSS**
+
+```bash
+cd /home/danix/Programming/GIT/danix.xyz-hacker-theme && npm run build
+```
+
+Expected: exits 0, `themes/danix-xyz-hacker/static/css/main.min.css` updated.
+
+- [ ] **Step 4: Commit**
+
+```bash
+git add themes/danix-xyz-hacker/assets/css/main.css themes/danix-xyz-hacker/static/css/main.min.css
+git commit -m "style: add .back-to-top component class"
+```
+
+---
+
+### Task 2: Create `back-to-top.html` partial
+
+**Files:**
+- Create: `themes/danix-xyz-hacker/layouts/partials/back-to-top.html`
+
+- [ ] **Step 1: Create the partial file**
+
+```html
+<div
+  x-data="{ visible: false }"
+  @scroll.window="visible = (window.scrollY / (document.documentElement.scrollHeight - window.innerHeight)) >= 0.33"
+>
+  <button
+    x-show="visible"
+    x-cloak
+    x-transition:enter="transition ease-out duration-300"
+    x-transition:enter-start="opacity-0 translate-y-4"
+    x-transition:enter-end="opacity-100 translate-y-0"
+    x-transition:leave="transition ease-in duration-200"
+    x-transition:leave-start="opacity-100 translate-y-0"
+    x-transition:leave-end="opacity-0 translate-y-4"
+    class="back-to-top"
+    aria-label="{{ i18n "back_to_top" | default "Back to top" }}"
+    type="button"
+    @click="window.scrollTo({ top: 0, behavior: window.matchMedia('(prefers-reduced-motion: reduce)').matches ? 'auto' : 'smooth' })"
+  >
+    <svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true" focusable="false">
+      <polyline points="18 15 12 9 6 15"></polyline>
+    </svg>
+  </button>
+</div>
+```
+
+Note: SVG is Feather `chevron-up` inlined to avoid race condition with `feather.replace()` running before Alpine shows the button. `aria-hidden="true"` on the SVG because the button has `aria-label`.
+
+- [ ] **Step 2: Add i18n keys**
+
+In `themes/danix-xyz-hacker/i18n/en.yaml`, add:
+```yaml
+back_to_top: "Back to top"
+```
+
+In `themes/danix-xyz-hacker/i18n/it.yaml`, add:
+```yaml
+back_to_top: "Torna in cima"
+```
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add themes/danix-xyz-hacker/layouts/partials/back-to-top.html themes/danix-xyz-hacker/i18n/en.yaml themes/danix-xyz-hacker/i18n/it.yaml
+git commit -m "feat: add back-to-top partial with Alpine.js and i18n"
+```
+
+---
+
+### Task 3: Include partial in `baseof.html`
+
+**Files:**
+- Modify: `themes/danix-xyz-hacker/layouts/_default/baseof.html`
+
+- [ ] **Step 1: Locate the `.Kind "page"` block for reading-progress (lines ~28–34)**
+
+```html
+{{ if eq .Kind "page" }}
+<div
+  id="reading-progress"
+  class="fixed top-0 left-0 h-1 transition-all duration-100"
+  style="width: 0%; background: linear-gradient(to right, var(--accent), var(--accent2)); z-index: 9999;"
+></div>
+{{ end }}
+```
+
+- [ ] **Step 2: Add the partial include inside the same condition block**
+
+```html
+{{ if eq .Kind "page" }}
+<div
+  id="reading-progress"
+  class="fixed top-0 left-0 h-1 transition-all duration-100"
+  style="width: 0%; background: linear-gradient(to right, var(--accent), var(--accent2)); z-index: 9999;"
+></div>
+{{ partial "back-to-top.html" . }}
+{{ end }}
+```
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add themes/danix-xyz-hacker/layouts/_default/baseof.html
+git commit -m "feat: include back-to-top button on single pages"
+```
+
+---
+
+### Task 4: Verify end-to-end
+
+- [ ] **Step 1: Start Hugo dev server**
+
+```bash
+cd /home/danix/Programming/GIT/danix.xyz-hacker-theme && hugo server -D
+```
+
+- [ ] **Step 2: Open an article page and scroll past 33%**
+
+Navigate to any article. Confirm the purple circle button slides up from bottom-right.
+
+- [ ] **Step 3: Scroll back above 33%**
+
+Confirm button fades/slides out.
+
+- [ ] **Step 4: Click button**
+
+Confirm smooth scroll to top.
+
+- [ ] **Step 5: Keyboard accessibility**
+
+Tab to the button when visible. Confirm focus ring (purple outline). Press Enter — confirm scroll to top.
+
+- [ ] **Step 6: Reduced motion**
+
+DevTools → Rendering → "Emulate prefers-reduced-motion: reduce". Scroll past 33% — button appears instantly (no animation). Click — page jumps instantly (no smooth scroll).
+
+- [ ] **Step 7: z-index layering**
+
+Confirm button sits below fixed header, search modal, and toast notifications.
+
+- [ ] **Step 8: Non-article pages**
+
+Navigate to home or list page. Confirm no button appears.
+
+- [ ] **Step 9: Final CSS rebuild and commit**
+
+```bash
+npm run build
+git add themes/danix-xyz-hacker/static/css/main.min.css
+git commit -m "build: rebuild CSS for back-to-top button"
+```
+
+- [ ] **Step 10: Update TODO.md**
+
+```markdown
+- [✅] add back-to-top button
+```
+
+```bash
+git add TODO.md
+git commit -m "chore: mark back-to-top as complete in TODO"
+```