Frontend Slides Editable

Create zero-dependency, animation-rich HTML presentations that run entirely in the browser with a built-in editor: move objects, multi-select with Ctrl+click, alignment snapping, simple text formatting with font family + size controls, undo/redo, a Pages sidebar (slide thumbnails, drag to reorder, delete), presentation tools (Laser pointer and Fullscreen), Ctrl+S persistence, and export HTML.

This skill is a copy of the frontend-slides skill extended with the editable deck runtime. For read-only decks without editor weight, use the original frontend-slides skill instead (same skills directory layout).

Parity with parent frontend-slides (style flexibility)

Adding edit mode must not replace preset authoring. The parent skill treats each choice in STYLE_PRESETS.md as a spec: per preset you implement its Layout prose, Signature Elements, typography, and colors — title slides and content slides differ across presets (e.g. Bold Signal’s card + big numerals vs. Notebook Tabs’ paper + edge tabs vs. Swiss Modern’s grid + red bar).

Normative behavior in Phase 3:

1. Read STYLE_PRESETS for the chosen preset(s) and reflect layout + signatures in HTML/CSS, not only :root colors and fonts.
2. The editable reference (examples/editable-deck-reference.html) supplies JS/CSS patterns (chrome, sidebar, objects, history) — not a frozen slide layout to paste on every deck. Do not reuse one generic “title + subtitle + corner rounded rectangle” geometry for every style.
3. examples/generated/presets/*.html are sample decks, not a layout shortcut. The 12 legacy samples are runtime smoke + visual previews; the 34 ported samples are real-template ports from beautiful-html-templates using the shared Swiss/reference runtime plus locked slot editing. For real deliveries, match the chosen preset/template grammar instead of reusing a generic README deck.
4. Static chrome (decorations that should not be draggable) may live outside .slide-edit-layer (e.g. background pseudo-elements, fixed nav chrome) per preset; movable copy and blocks stay as [data-slide-object] inside the layer.

If runtime constraints ever conflict with a signature element, adapt the element (e.g. implement the same visual with CSS, or split into multiple objects) — do not drop preset identity for the sake of a single template.

For the 34 ported presets from beautiful-html-templates, prefer the upstream template's mood / tone / density and visual grammar over color-token matching alone.

Interaction baseline: ported decks must use the same Swiss/reference editor chrome and object editor as examples/editable-deck-reference.html / swiss-modern.html. Native template slots are locked-layout content slots; user-added objects are normal [data-slide-object][data-oid] objects.

Important interaction contract: data-edit-slot is editable content, not a draggable component. In edit mode the user can click slot text/images to change their content with RTE/Undo/Redo/Save/Export, but the upstream template's layout grid, card geometry, decorative layers, and spacing stay locked. Only user-added objects in .slide-edit-layer become selectable, draggable, resizable components. Do not promise that every native template child will get object handles unless a separate componentization mode is explicitly requested and implemented.

Template edit modes:

• data-template-edit-mode="slots" is the default. It is template-safe: authored content is editable through slots, while layout and decoration remain locked.
• data-template-edit-mode="components" is an optional generated mode for semantic blocks that can be represented as [data-slide-object].
• In delivered ported decks, Unlock layout componentizes the current slide on demand by moving/wrapping the original editable slot nodes into .slide-edit-layer. It must preserve the original element tag, classes, and computed typography, must not create duplicate content copies, and must be undoable back to the original layout position.
• Never componentize every DOM node. Exclude backgrounds, grids, axes, ticks, decorative marks, texture/glitch layers, SVG paths, animation wrappers, and pure layout containers.

When using or extending a ported preset:

1. Treat the matching beautiful-html-templates/templates/{source_slug}/template.html as the visual system: preserve fonts, CSS variables, slide-level classes, layout grid, decorative DOM, and component grammar.
2. Edit authored content through slots, not by decomposing the template into draggable boxes. Use:
   • data-edit-slot
   • data-slot-type="text|image|metric|table-cell"
   • data-slot-label
   • data-slot-locked-layout="true"
3. Keep decorative elements locked unless the user should naturally change that exact item. Grids, paper texture, hairlines, scan lines, pixel/glitch layers, ornamental marks, and layout containers should not become draggable objects.
4. Preserve .slide-edit-layer for user-added freeform objects. Added objects can use [data-slide-object][data-oid] and the normal Swiss drag/resize/multi-select runtime; native template slots use the Swiss RTE/Undo/Redo/Save/Export path but do not get move/resize handles.
5. If a needed slide type is missing, design a new slide in the same template system: same fonts, palette, spacing rhythm, chrome, and component grammar. Do not mix in another template's visual language.

Models often jump straight to generating HTML. For Mode A (new deck) and Mode B (PPT or PDF) after extraction, you must finish Phase 1 before Phase 2, and Phase 2 before Phase 3 — unless a narrow exception below applies.

Hard rule: Unless the user provides in one turn (or one clearly scoped batch) every item in the Phase 1 checklist, you must run Phase 1 first as one grouped message (or a structured question UI). If the batch is incomplete, send only the missing checklist items in the next message — do not guess slide count, outline depth, preset, or language. Invoking /frontend-slides-editable or attaching this skill does not waive discovery. A one-liner (e.g. “用 skill 介绍它自己”, “做一份某某主题的演示”) is topic / intent only, not a brief.

Phase 1 checklist (complete brief — all required without model inference):

Images vs outline: Co-design outline ↔ images (Step 1.2) only after the user has real assets or links to evaluate. Do not skip Phase 1 dimensions just because images are pending; capture “yes, will provide” in Phase 1, then run image evaluation when files exist.

Mode B (PPT / PDF): After extract-pptx.py (.pptx) or extract-pdf.py (.pdf), present titles/summaries/asset counts and still run Phase 1 for anything extraction does not decide: length goals if restructuring, style direction, editing scope, locale, and image handling notes on extracted assets. Do not jump from “here’s the extract” straight to only style picking — close Phase 1 gaps first, then Phase 2, then codegen.

When Phase 1 and/or Phase 2 may be shortened (narrow exceptions only):

1. Explicit opt-out — User clearly skips discovery and/or previews (e.g. “跳过发现，你全部决定”, “no discovery — just generate”).
2. Complete written brief — Same batch already satisfies every Phase 1 checklist row without you guessing, and either (a) a named preset is chosen so Phase 2 can be a direct handoff to Phase 3, or (b) the user explicitly allows no previews and accepts your single recommended preset.

Default order: Phase 1 (grouped) → Phase 2 (show, don’t tell) → Phase 3. Never start Phase 3 to “save turns.”

Partial answers: Next message = only missing Phase 1 items, then resume Phase 2.

Never infer silence as approval. Mode C (enhance existing HTML): precise change list may skip full Phase 1–2; vague “make it better” → 1–2 clarifying questions first.

Anti-pattern: Generating HTML because the skill was attached or because you “already know” a good length or preset — failure mode.

Skipping discovery to “save turns” is a failure mode for this skill.

1. Zero Dependencies — Single HTML files with inline CSS/JS. No npm, no build tools.
2. Show, Don't Tell — Generate visual previews, not abstract choices. People discover what they want by seeing it.
3. Distinctive Design — No generic "AI slop." Every presentation must feel custom-crafted.
4. Viewport Fitting (NON-NEGOTIABLE) — Every slide MUST fit exactly within 100vh. No scrolling within slides, ever. Content overflows? Split into multiple slides.

You tend to converge toward generic, "on distribution" outputs. In frontend design, this creates what users call the "AI slop" aesthetic. Avoid this: make creative, distinctive frontends that surprise and delight.

Focus on:

• Typography: Choose fonts that are beautiful, unique, and interesting. Avoid generic fonts like Arial and Inter; opt instead for distinctive choices that elevate the frontend's aesthetics.
• Color & Theme: Commit to a cohesive aesthetic. Use CSS variables for consistency. Dominant colors with sharp accents outperform timid, evenly-distributed palettes. Draw from IDE themes and cultural aesthetics for inspiration.
• Motion: Use CSS-only animations and transitions in generated decks (this skill outputs single-file HTML, no React and no Motion library). Focus on high-impact moments: one well-orchestrated load with staggered reveals (animation-delay) beats scattered micro-interactions.
• Backgrounds: Create atmosphere and depth rather than defaulting to solid colors. Layer CSS gradients, use geometric patterns, or add contextual effects that match the overall aesthetic.

Avoid generic AI-generated aesthetics:

• Overused Latin font families (Inter, Roboto, Arial, bare system defaults) — note a curated CJK system stack is the correct portable choice and is not "generic" in this sense (see Phase 3 §Fonts & portability)
• Cliched color schemes (particularly purple gradients on white backgrounds)
• Predictable layouts and component patterns
• Cookie-cutter design that lacks context-specific character

Interpret creatively and make unexpected choices that feel genuinely designed for the context. Vary between light and dark themes, different fonts, different aesthetics. You still tend to converge on common choices (Space Grotesk, for example) across generations. Avoid this: it is critical that you think outside the box!

These invariants apply to EVERY slide in EVERY presentation:

• Every .slide must have height: 100vh; height: 100dvh; overflow: hidden;
• ALL font sizes and spacing must use clamp(min, preferred, max) — never fixed px/rem
• Content containers need max-height constraints
• Images: max-height: min(50vh, 400px)
• Breakpoints required for heights: 700px, 600px, 500px
• Include prefers-reduced-motion support
• Never negate CSS functions directly (-clamp(), -min(), -max() are silently ignored) — use calc(-1 * clamp(...)) instead

When generating, read viewport-base.css and include its full contents in every presentation.

Content Density Limits Per Slide

Content exceeds limits? Split into multiple slides. Never cram, never scroll.

Determine what the user wants:

• Mode A: New Presentation — Create from scratch. Go to Phase 1.
• Mode B: PPT / PDF conversion — Convert a .pptx or .pdf file. Go to Phase 4.
• Mode C: Enhancement — Improve an existing HTML presentation. Read it, understand it, enhance. Follow Mode C modification rules below.

When enhancing existing presentations, viewport fitting is the biggest risk:

1. Before adding content: Count existing elements, check against density limits
2. Adding images: Must have max-height: min(50vh, 400px). If slide already has max content, split into two slides
3. Adding text: Max 4-6 bullets per slide. Exceeds limits? Split into continuation slides
4. After ANY modification, verify: .slide has overflow: hidden, new elements use clamp(), images have viewport-relative max-height, content fits at 1280x720
5. Proactively reorganize: If modifications will cause overflow, automatically split content and inform the user. Don't wait to be asked

When adding images to existing slides: Move image to new slide or reduce other content first. Never add images without checking if existing content already fills the viewport.

Centralize Phase 1: For Mode A and for Mode B after extraction, deliver the checklist in one grouped interaction (see Discovery gate above) — not dribbled across many turns. If the user’s first message is incomplete, only ask missing items next.

Do not jump to style previews or HTML until Phase 1 is satisfied (exceptions: Discovery gate).

Ask ALL discovery questions (1–6 below) in that grouped interaction when starting from scratch. Use a structured question tool when available; otherwise one concise message:

Question 1 — Purpose (header: "Purpose"): What is this presentation for? Options: Pitch deck / Teaching-Tutorial / Conference talk / Internal presentation

Question 2 — Length (header: "Length"): Approximately how many slides? Options: Short 5-10 / Medium 10-20 / Long 20+

Question 3 — Content (header: "Content"): Do you have content ready? Options: All content ready / Rough notes / Topic only

Question 4 — Style preference (header: "Style Pref"): What visual direction sounds closest as a starting point? Options:

• "Recommend for me" — infer from audience, topic, and content
• "Clean / Professional" — restrained, polished, trustworthy
• "Bold / Experimental" — high-contrast, energetic, surprising
• "Editorial / Warm" — human, crafted, story-forward
• "Technical / Minimal" — precise, structured, product-like
• "I already know the preset" — skip to a direct preset choice

Question 5 — Editing scope (header: "Editing"): Confirm the user wants the full editable runtime (default for this skill): object layout, Pages sidebar, undo/redo. If they explicitly want a minimal read-only file only, switch to the parent frontend-slides skill instead — do not strip the runtime from this skill arbitrarily.

Question 6 — Assets / images (header: "Images"): Will this deck use image files you will provide (folder, uploads, or links)? Options: No images (CSS/graphics only) / Yes — I will provide images / Unsure — recommend

Question 7 — Mobile adaptation (header: "Mobile"): Should this editable deck be adapted for phone use in both portrait and landscape? Options: Desktop-first only (recommended; keeps the deck optimized for presenting/editing on desktop) / Adapt for phone portrait + landscape (adds mobile-specific CSS hooks, sidebar behavior, and extra viewport verification). This is a required Phase 1 answer for new decks and for PPT/PDF conversions after extraction.

Language / locale (include in the same grouped message when relevant): If the deliverable must be monolingual, bilingual, or localized (e.g. CN/EN on the same slides vs two files), ask once here when the user has not already stated it.

If the user has draft content (bullets, doc, outline), ask them to paste or attach it in the same turn or immediately after Phase 1.

If Question 6 was No images or the user has not supplied any image files yet → proceed to Phase 2 after Phase 1 is otherwise complete (you may still ask them to add images later before Phase 3 if they change their mind).

If user provides an image folder (or links) after Phase 1 marked images as yes:

1. Scan — List all image files (.png, .jpg, .svg, .webp, etc.)
2. Inspect each image — Use the host's available image/file viewing capability
3. Evaluate — For each: what it shows, USABLE or NOT USABLE (with reason), what concept it represents, dominant colors
4. Co-design the outline — Curated images inform slide structure alongside text. This is NOT "plan slides then add images" — design around both from the start (e.g., 3 screenshots → 3 feature slides, 1 logo → title/closing slide)
5. Confirm the outline in one grouped follow-up (structured question UI when available): "Does this slide outline and image selection look right?" Options: Looks good / Adjust images / Adjust outline

Logo in previews: If a usable logo was identified, embed it (base64) into each style preview in Phase 2 — the user sees their brand styled three different ways.

Start only after Phase 1 is complete (see Discovery gate).

Purpose: Narrow the aesthetic visually — most people can’t name what they want. Use HTML previews (and concrete anchors from STYLE_PRESETS.md + repo examples: examples/generated/presets/ smoke decks, examples/editable-deck-reference.html for runtime chrome) so the user picks direction, then preset or mix.

This is the "show, don't tell" phase.

Step 2.0: Style Preference First

Start from the style preference captured in Phase 1. Before asking the user how they want to choose, give a short recommendation list of 2-4 presets that best match their preference, audience, and content. Tie names to STYLE_PRESETS rows (and, when helpful, “see generated sample *.html for slug X”) so choices are grounded, not abstract.

Use this mapping as the starting point:

Explain the recommendation briefly in concrete terms, for example: audience fit, energy level, brand tone, or content density.

If the user already chose "I already know the preset" in Phase 1, skip Step 2.1 and go straight to the preset picker.

Step 2.1: Style Path

Ask how they want to choose (header: "Style"):

• "Pick from recommendations" (recommended) — Choose directly from the suggested presets (still show thumbnails or one-liner visual cues from presets when possible)
• "Show me options" — Generate 3 single-slide HTML previews (Step 2.3) to shrink the search space before locking a preset
• "I know what I want" — Pick from the full preset list in STYLE_PRESETS.md

If direct preset name: Confirm against STYLE_PRESETS, then Phase 3. If "you choose" from Phase 1: Default path = recommendations + offer previews before generating.

Ask (header: "Vibe", multiSelect: true, max 2): What feeling should the audience have? Options:

• Impressed/Confident — Professional, trustworthy
• Excited/Energized — Innovative, bold
• Calm/Focused — Clear, thoughtful
• Inspired/Moved — Emotional, memorable

Use the user's style preference and recommended preset cluster to steer this question. If the preference already strongly determines the direction, keep the previews within that neighborhood instead of scattering across unrelated aesthetics.

Step 2.3: Generate 3 Style Previews

Based on mood and the earlier style preference, generate 3 distinct single-slide HTML previews showing typography, colors, animation, and overall aesthetic. Read STYLE_PRESETS.md for available presets and their specifications.

Save previews under a project-local scratch folder (e.g. .claude-design-slide-previews/ or .design/slide-previews/) as style-a.html, style-b.html, style-c.html. Each should be self-contained, ~50-100 lines, showing one animated title slide.

Open each preview in the default browser when possible: macOS open path/to/file.html; Linux xdg-open path/to/file.html; Windows start path\to\file.html.

When possible, keep at least 2 of the 3 previews within the recommended preset family so the user sees relevant variations before they see outliers.

Ask (header: "Style"): Which style preview do you prefer? Options: Style A: [Name] / Style B: [Name] / Style C: [Name] / Mix elements

If "Mix elements", ask for specifics.

Generate the full presentation using content from Phase 1 (text, or text + curated images) and style from Phase 2.

If images were provided, the slide outline already incorporates them from Step 1.2. If not, CSS-generated visuals (gradients, shapes, patterns) provide visual interest — this is a fully supported first-class path.

Before generating, read these supporting files:

• STYLE_PRESETS.md — Authoritative visual spec for the chosen preset (layout, signature, fonts, colors) — same role as in parent frontend-slides
• editor-runtime.md — DOM contract (data-slide-object, data-oid, edit layer), history types, snap rules, generator checklist
• examples/editable-deck-reference.html — Copy the deck runtime (editor + sidebar + history + persistence patterns); do not treat its slide markup as the only allowed layout
• html-template.md — HTML architecture and integration notes
• viewport-base.css — Mandatory CSS (include in full)
• animation-patterns.md — Animation reference for the chosen feeling
• For ported presets, also read local beautiful-html-templates/templates/{source_slug}/template.html and template.json when available; use STYLE_PRESETS.md as the index, but the upstream template as the detailed design grammar.

Key requirements:

• Single self-contained HTML file, all CSS/JS inline
• All authored images and videos must be embedded into the HTML as data: URLs by default; assets/ paths are allowed only as temporary extraction inputs before generation, never as delivered media src values.
• Include the FULL contents of viewport-base.css in the <style> block
• Preset fidelity: Implement Layout and Signature Elements from STYLE_PRESETS.md for the selected style. Vary structure slide-to-slide and preset-to-preset; avoid a single repeated title-slide prototype across all aesthetics (parent skill does not do that).
• Ported preset fidelity: For the 34 ported presets, preserve the upstream template DOM/CSS/classes and make authored content slot-editable. Prefer locked native layout + editable data-edit-slot content over making every native element draggable.
• Every slide section.slide must have a stable id; movable content lives in .slide-edit-layer as [data-slide-object][data-oid] per editor-runtime.md
• Deck slide list: Never use a global querySelectorAll('section.slide') when a filmstrip clones slides — use only slides under the deck wrapper (e.g. .slides-offset + :scope > section.slide). See html-template.md §Regression guard.
• Mobile adaptation: If Phase 1 selected phone support, set data-mobile-adaptation="enabled" on <html> and include portrait + landscape media rules for the deck chrome, sidebar, and slide objects. If not selected, set data-mobile-adaptation="desktop-default" so validation can distinguish an explicit desktop-first choice from an omitted decision.
• Embed the editable deck runtime (from the reference example): SlideDeck, object editor (select / drag / snap / RTE toolbar), SlideSidebar, HistoryStack, save/export
• Fonts (see §Fonts & portability below): For Latin display/body, prefer distinctive Fontshare or Google Fonts over generic system faces. For CJK (Chinese/Japanese/Korean) text, use a curated system CJK stack — full CJK webfonts are multi-megabyte and break the single-file/self-contained promise, so a well-chosen native stack is the correct choice here, not "AI slop". Never leave Latin body text on a bare Arial/Inter/system default just to avoid a link.
• Add detailed comments explaining each section
• Every section needs a clear /* === SECTION NAME === */ comment block

The exported file must stay single-file and self-contained — no external font links (see Phase 5). That constrains font choices; do not ignore it:

• Latin display/body: A distinctive Fontshare/Google face is encouraged for character. But a plain <link rel="stylesheet" href="https://fonts..."> makes the export depend on the network — open offline and the type silently falls back. Choose one:
  1. Self-host inline — embed the Latin webfont as base64 @font-face src: url(data:font/woff2;base64,...) so it travels in the file (best fidelity, larger file), or
  2. Layered fallback — link the webfont for the live/edit experience but pair it with a strong same-category system stack so an offline export degrades gracefully, not to bare Arial. The export sanitizer strips leftover external font <link>s, so an un-inlined webfont will fall back in the delivered file — pick (1) when fidelity matters.
• CJK (中文 / 日本語 / 한국어): Do not chase a CJK webfont — full coverage is multiple megabytes and cannot be inlined into a single-file deck. Use a curated native CJK stack, e.g. "PingFang SC","Hiragino Sans GB","Microsoft YaHei","Source Han Sans SC","Noto Sans CJK SC",sans-serif. This is the correct, portable choice for CJK — not a quality compromise. Latin glyphs in a CJK deck can still use a webfont via an earlier family in the stack.
• Mixed CN/EN decks: Put the Latin display face first, then the CJK stack, so headings get character while CJK body renders in a clean native face: "Clash Display","PingFang SC",....

When converting PowerPoint (.pptx) or PDF (.pdf) files:

1. Extract content
   • PPTX: python3 scripts/extract-pptx.py <input.pptx> <output_dir> (install python-pptx if needed: pip install python-pptx)
   • PDF: python3 scripts/extract-pdf.py <input.pdf> <output_dir> (install PyMuPDF if needed: pip install pymupdf). Optional: --raster-if-empty renders a page to PNG when that page has no extractable text and no embedded images (e.g. scanned-like pages still need separate OCR; this flag only captures a bitmap of the page).
   • Both writers emit the same intermediate: extracted-slides.json + assets/ (one record per slide/page; PDF has no speaker notes — use notes: "").
2. Confirm with user — Present extracted slide/page titles, content summaries, and image counts
3. Phase 1 (close gaps) — Extraction supplies content, but you still need explicit answers for anything not fixed by the file: style direction (or preset/delegate), full editable vs read-only, locale, length intent if merging/splitting slides, and image handling on extracted assets. One grouped follow-up for missing items only.
4. Phase 2 — Style discovery (previews / preset pick); see Phase 2: Style Discovery in this skill file
5. Generate HTML — Convert to chosen style, preserving all text, images (from assets/), slide order; PPTX: speaker notes as HTML comments. PDF: no notes in source — omit or leave comment placeholders only if the user supplies them separately.

PDF caveats: Text reading order and “title vs body” are heuristic; layout is not object-level like PPTX. Image-only PDFs need --raster-if-empty or external OCR for usable text.

1. Clean up — Delete the temporary slide-previews folder (see Phase 2) if it exists
2. Smoke check (quick) — Before handing off: open the file once; confirm no in-slide scrolling at ~1280×720; if mobile support was selected, also check ~390×844 portrait and ~844×390 landscape; in edit mode, open Pages, reorder one slide, Copy one slide, add +New Page, and refresh — no duplicate slides or object ids (regression guard); Export HTML opens and runs standalone
3. Open — Launch in default browser: macOS open [filename].html; Linux xdg-open [filename].html; Windows start [filename].html
4. Summarize — Tell the user:
   • File location, style name, slide count
   • Navigation: Arrow keys, Space, scroll/wheel (wheel disabled while edit mode on), click nav dots
   • Presentation tools: Hover the top-left to reveal Laser and Fullscreen. Laser shows a single laser dot that follows the pointer (the trailing-stroke effect was removed by design — no trail nodes are created); Esc turns it off, and entering edit mode closes it automatically. Fullscreen uses the browser Fullscreen API.
   • Edit mode: E enters edit mode. Hover the top-left to reveal Edit, Pages, and (while editing) Undo / Redo / Done; controls hide after the pointer leaves (~400ms). Done (same cluster) exits edit mode — the Edit button label stays Edit. Esc blurs text first, then exits edit mode when not typing in a text box
   • Pages sidebar for thumbnails, reorder (drag rows), hover Copy on a thumbnail to duplicate that page, delete slides, and use +New Page beside Export HTML to insert a blank style-matched page after the current slide
   • Objects: drag ⠿ to move; hover × on an object or use Delete/Backspace to remove (multi-select confirms in English); drag corner resize on selected objects to change width/height (text reflows); Ctrl+click multi-select (macOS: Control key)
   • Add element: Add element (top-left with Edit/Pages in edit mode) opens a menu: Text, Image (local file, paste, or placeholder), Video (local file + controls); added media is embedded as data URLs so exported decks travel as one file
   • Snap: aligns to slide center and other objects — not to the outer slide edges
   • Text: click text to type; floating toolbar: B/I plus Font · Scale · Px drawers (click to expand cards for families, scale steps, px presets + custom); Ctrl+Z / Ctrl+Y or Ctrl+Shift+Z; Cmd+Z / Cmd+Y / Cmd+Shift+Z on macOS when not typing in contenteditable
   • Save (#btnSave, top-left next to Edit / Pages when editing — same hover reveal) or Ctrl+S / Cmd+S stores a browser draft in localStorage and writes a portable HTML file when the browser supports File System Access; otherwise it downloads an updated HTML fallback. Export HTML remains in the Pages sidebar and must embed the current deck state plus media into the exported file while stripping transient edit state. The exported file is portable, single-file, self-contained (no external font links), and trail-free — it carries the latest edits and keeps Laser/Fullscreen working, but never embeds active laser state.
   • How to customize: slide theme :root variables, --deck-chrome-* for edit UI (see STYLE_PRESETS.md §Deck chrome tokens), fonts (inline Latin webfonts as base64 @font-face or layered system stacks, and a native CJK stack — see Phase 3 §Fonts & portability; the export stays self-contained with no external font links), .reveal animations; keep data-oid unique when adding objects