HTML → PDF Slide Workflow#

‼️ STOP — Read Before Doing Anything#

Before writing a single line of code or HTML, you MUST complete these two confirmation steps in order. Do not proceed until you receive explicit user approval for each.

Confirmation 1 of 2: Design Style#

Analyze the user's input (image / URL / keyword / .pptx), then show a design spec summary and ask:

Here's the design style I extracted from [source]:

• Background: #000 dark / Accent: #2997FF blue
• Font: SF Pro Display, oversized heading, minimal whitespace
• Style: dark Keynote, glow effects

Does this match what you want? Any changes before I start?

If the user provided a website URL and fetching fails (Fake IP, login wall, etc.):

• Say exactly why it failed
• Ask: "Could you send a few screenshots of the site? I'll analyze the design from those."
• Do NOT assume or default to any style

Wait for explicit approval → then move to Confirmation 2.

Confirmation 2 of 2: Slide Content#

Ask the user if they have existing materials:

Do you have reference materials for the content? (existing PPT, doc, data, bullet points — anything works) If yes, send them over. If not, I'll draft an outline for you to review.

Once you receive a reply, prepare a numbered list: slide title + one-line summary per slide. Show it and ask:

Here's the planned structure — does this look right? Anything to add, remove, or change?

Wait for explicit approval → only then begin generating HTML.

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If either confirmation is skipped, the workflow is broken. Start over from Confirmation 1.

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export_pdf.js auto-detects Chrome in this order:

1. Puppeteer bundled Chromium ( npm install puppeteer)
2. System Chrome/Chromium (macOS: /Applications/Google Chrome.app, Linux: /usr/bin/chromium)
3. If neither found → prints a clear error with install instructions, exits

If npm install puppeteer fails (sandbox/network restriction):

bash

# Option A: skip Chromium download, install separately
npm install puppeteer --ignore-scripts
npx puppeteer browsers install chrome

# Option B: use puppeteer-core (no bundled Chrome download)
npm install puppeteer-core
# script will auto-find system Chrome

# Option C: install system Chrome first, then run script
# macOS: brew install --cask google-chrome
# Linux: sudo apt install chromium-browser
npm install puppeteer-core

Do NOT fall back to wkhtmltopdf, pdfkit, weasyprint, or any other tool.

For full installation instructions across OpenClaw, Claude Code, Codex, and Linux/macOS setup, see references/install.md.

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Workflow Overview#

text

User input (image / website URL / style keyword / .pptx file)
    ↓ Step 1: Extract design spec → ⚠️ Confirm with user
    ↓ Step 2: Outline slide content → ⚠️ Confirm with user
    ↓ Step 3: Generate HTML → 💾 Save slides.html to disk
    ↓ Step 4: Run export_pdf.js → 💾 Output slides.pdf

Both slides.html and slides.pdf must exist as final outputs.

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⚠️ Two Mandatory Confirmation Gates (never skip)#

Gate 1: Design Style#

After analyzing the input, show the extracted design spec summary and ask for confirmation:

Here's what I extracted from [source]:

• Background: #000000 black · Accent: #2997FF apple blue
• Font: SF Pro Display, oversized centered headline
• Style: dark Keynote, glow effects

Does this match the style you want? Any adjustments?

⚠️ If website fetch fails (e.g. Fake IP / login required):

• Tell the user clearly why it failed
• Ask for screenshots: "Could you send a few screenshots of the site? I'll analyze the design from those."
• Never assume or default to any style — wait for user confirmation before proceeding

Website analysis priority:

1. Puppeteer screenshot → visual analysis (most accurate)
2. web_fetch page content → CSS/font extraction
3. Ask user to send screenshots

Gate 2: Slide Content#

First ask if the user has existing materials:

Do you have any reference materials for the content? e.g. existing PPT, doc, report, or a list of key points? Send them over and I'll structure the slides — otherwise I'll draft an outline for you to review.

After receiving a reply, prepare a one-line summary per slide and confirm before generating HTML.

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Step 1: Extract Design Spec → DESIGN.md#

Supported inputs:

InputApproach📂 .pptx templateParse with python-pptx: extract colors, fonts, backgrounds, placeholder layouts (most accurate)📎 Image / screenshotVisual analysis: colors, font style, spacing, component patterns🌐 Website URLPuppeteer screenshot + getComputedStyle font/color extraction💬 Style keywordUse brand knowledge: Apple → SF Pro, Notion → Inter, Linear → Inter, Google → Google Sans

Extracting from .pptx:

python

from pptx import Presentation
prs = Presentation("template.pptx")
slide = prs.slides[0]
for shape in slide.shapes:
    if shape.has_text_frame:
        for para in shape.text_frame.paragraphs:
            for run in para.runs:
                print(run.font.name, run.font.size, run.font.color.rgb, run.font.bold)

Fill extracted values into DESIGN.md (see references/DESIGN_TEMPLATE.md):

• Colors: primary bg, secondary bg, text colors, accent, border → CSS variables
• Fonts: heading / body / decorative number — name, weight, size range per level
• Layout: padding, max-width, grid columns, gap, border-radius
• Components: card, badge/label, button, divider, background decoration
• Section list: CSS class + content theme + dark/light tone per slide

Font extraction by input type:

InputMethod.pptx``run.font.name per text runWebsitegetComputedStyle(el).fontFamily via PuppeteerImage / screenshotVisual analysis — describe closest match (e.g. "geometric sans, similar to Helvetica")Style keywordBrand knowledge mapping

Fonts go into DESIGN.md as CSS variables. Append Chinese fallbacks at the end (never hardcode them as primary):

css

--font-heading: 'SF Pro Display', 'PingFang SC', 'Helvetica Neue', sans-serif;
--font-body:    'SF Pro Text',    'PingFang SC', 'Helvetica Neue', sans-serif;

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Step 3: Generate HTML#

⚠️ Save the HTML to a .html file first. Do not merge HTML generation and PDF export into one step. The HTML file is a required intermediate artifact — it must exist on disk before running export_pdf.js.

Generate a single .html file and write it to disk (e.g. slides.html):

• Single file, all CSS inlined, zero external dependencies
• Each slide = one <section class="...">, fixed width 1440px, height fits content
• Fonts from DESIGN.md — Chinese fallback appended, never hardcoded as primary
• @media print: page-break-after: always on every section

Font consistency check after saving:

bash

grep -n "font-family" slides.html

Only proceed to Step 3 once the .html file is saved and verified.

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Step 4: Export PDF via Puppeteer#

⚠️ Only use export_pdf.js (Puppeteer screenshot-and-compose). Do NOT use any of these alternatives — they all produce broken output:

• page.pdf() directly → A4 portrait, white space below every slide
• wkhtmltopdf → outdated WebKit engine, broken flexbox/grid/modern CSS
• Any other HTML-to-PDF CLI (Prince, WeasyPrint, pdfkit, etc.) → layout incorrect

The screenshot-and-compose approach is the only method that faithfully preserves the rendered layout.

Environment matters#

Claude Code / Codex / OpenClaw / local agent (can run shell commands):

• Read scripts/export_pdf.js, copy it to the project directory, run it:

bash

node export_pdf.js              # reads slides.html → slides.pdf (auto-detects <section> elements)
node export_pdf.js my-deck.html # specify a different file

Claude.ai chat / any chat-only interface (cannot run shell commands):

• Your role ends at Step 3: generate the HTML and provide it to the user
• Tell the user: "Here's your slides.html. To export the PDF, copy scripts/export_pdf.js from the skill folder to the same directory and run node export_pdf.js."
• Do NOT attempt to run Puppeteer, install npm packages, or use any PDF tool in chat

Auto-detection: The script automatically finds all <section> elements in DOM order — no need to manually set SELECTORS. Only configure SELECTORS manually if you need a custom slide order or to merge multiple elements into one slide:

js

// Optional manual override — leave as [] for auto-detect
const SELECTORS = [
  '.cover',
  '.section-2',
  ['.chart', '.stats'],  // array = merge into one slide
];

See references/export_pdf_guide.md for details.

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Troubleshooting#

IssueFixPDF has white space / broken layoutDo not use page.pdf(), wkhtmltopdf, or any CLI PDF tool. Run export_pdf.js only — it uses Puppeteer screenshot-and-compose to preserve layout exactlyChinese text renders as Song/MingAdd 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC' to font stack for cross-platform Chinese supportInconsistent fonts across slidesRun grep -n "font-family" slides.html and normalizeWrong page count in PDFCheck that SELECTORS covers all sectionsDetached Frame errorUse the reusable overlayPage pattern — never use newPage()/close() in a loopWebsite URL fails to fetchLikely Fake IP proxy — use Puppeteer screenshot instead, or ask user for screenshots