marp_slide_decks v1.0.0

name: "marp_slide_decks" description: "Author Marp slide decks from Markdown and run automated design checks: authoring flow (frontmatter, directives, layouts, themes), design-balance rules (density, typography, balance), dark/light theme validation, and export to HTML, PDF, or PPTX via marp-cli. Triggers on 'make slides', 'create a deck', 'build a presentation from markdown', 'marp deck', 'export slides to PDF or PPTX', or 'check my slide design'."

Marp Slide Decks

Purpose

Take a topic or an existing document and produce a finished Marp slide deck: authored Markdown, verified against design-balance and contrast rules, exported to the requested format. This skill covers the full loop, authoring plus automated design checks, not just pointers.

Workflow

1. Author: Start from assets/starter-deck.md. Put deck-wide settings in YAML frontmatter, split slides on ---, keep one idea per slide. Directives cheat sheet in references/authoring.md; design rules in references/design-rules.md.

1. Preview while iterating: Run the CLI in watch mode and open the served URL: npx @marp-team/marp-cli@latest -w deck.md (add --html if the deck uses raw HTML layouts).

1. Design check: Run the bundled checker against every draft, with the theme: python3 bin/design-check.py deck.md --theme theme.css Fix every FAIL before shipping. WARNs get a human judgment call. --strict tightens density caps for keynotes and investor decks.

1. Export: Pick the target and render:

• HTML (present from browser, presenter view, transitions): marp deck.md --html -o deck.html
• PDF (handouts, sharing): marp deck.md --pdf -o deck.pdf
• PPTX (handoff to a PowerPoint user; note: marp PPTX exports are flat images, not editable text) PDF/PPTX/image exports need a local browser (Chrome, Edge, or Firefox); pass --browser-path if the CLI cannot find one. Decks referencing local images need --allow-local-files.

1. Verify the export: Open the rendered output and confirm slides count, theme, backgrounds, and code blocks look right. Never hand off an export you have not opened.

Output Contract

• The deck source: one self-contained Markdown file with marp: true frontmatter.
• A clean design-check.py run (zero FAILs) at handoff; note any accepted WARNs.
• The exported artifact in the requested format(s), verified opened.
• The theme CSS file alongside the deck when a custom theme is used.

Operating Rules

• Never invent marp-cli flags. Verified set: --html, --pdf, --pptx, --png, --jpeg, --theme, --theme-set, --input-dir, --allow-local-files, --browser-path, -w, -s, -o, -c. Check marp --help before claiming anything else.
• Facts about Marp behavior come from the sources in scratch/marp-slide-decks-sources.md or a fresh web search, never from memory alone.
• One main idea per slide, max 6 bullets, code blocks under 12 lines, every image gets alt text. If a slide needs more, split the slide.
• Contrast is a hard gate: body text 4.5:1 minimum, large text 3:1 minimum (WCAG AA). Check both the light and dark palettes whenever a deck supports both.
• Prefer built-in themes (default, gaia, uncover) unless the deck needs brand styling. Custom themes go in plain CSS with a / @theme name / comment.