Marp Deck

marp-deck

A deck here is a keynote: black or white, one idea per slide, type you can read from the back of the room, and a picture whenever a picture says it better. This skill is the whole craft. Read it once, then write.

1. The shape of a keynote

Every talk, whatever the subject, follows this arc. Use it as the outline; drop what the talk does not need, never reorder what it keeps.

Ten slides for a ten-minute talk. A longer talk repeats 2–8 per act. A shorter one keeps 1, 4, 5, 7, 11. Section openers (section) mark each act.

2. Copy: write like the person on stage

• The headline is the sentence you would say out loud. Eight words or fewer. If it needs a comma, it is two slides.
• Say what it does for someone, not what it is. Benefit, then feature — if the feature is needed at all.
• One idea per slide. The check warns above 40 words; a keynote slide usually has fewer than
  15. Everything else goes in the speaker notes.
• Numbers made human. Convert to something a person can feel: time saved a day, songs in a pocket, cups of coffee. Round it. One number per slide.
• Threes. Three pillars, three reasons, three words. Not two, not five.
• Verbs, plain words, no jargon. No "leverage", "seamless", "robust", "solution". No adjectives that do not earn their place. No exclamation marks.
• Tension, then release. Problem, question, answer. The reveal slide is short; the audience finishes the sentence.
• Speaker notes carry the argument (<!-- notes --> under a slide). The slides carry the punch. Write the notes as spoken sentences, two to five per slide, so the presenter can read them cold — the pane's Presenter view shows them large beside the next slide, and that is where the user rehearses.
• Never a bulleted paragraph on a slide. If a list is unavoidable, it is three lines of three to five words each. The themes render lists as a clean stack with hairlines, no bullets.

3. Design: two themes, one accent, nothing else

Front matter — pick one theme for the whole deck:

---
marp: true
theme: keynote-dark      # or keynote-light. Never both in one deck.
paginate: true
---

• keynote-dark — black, white type. The keynote. Use it unless the talk is about paper, light, health, or the user asks for white.
• keynote-light — white, near-black type. Airy, daytime.

Rules the themes assume:

• Huge type, generous space. Headlines up to 132px. Do not shrink text to fit; cut words.
• One image per slide at most. Full bleed (![bg](…)) or centred (![w:1000](…)). No image next to a paragraph.
• Art is generated, not found. No clip art, no stock photos, no emoji, no icons. Wallpapers for hero/section/closing, charts for numbers, device frames for screens (section 4). A photo the user supplies goes full bleed or in a frame.
• One accent colour per deck, #2997ff by default (links, chart bars). Change it only with a reason, then keep it.
• Consistency is the design. Same overline style, same positions, same wallpaper palette through the deck. Pick a palette on slide 1 and stay with it.

The slide classes

Set one per slide with a scoped directive on the slide's first line, then the content:

<!-- _class: hero -->
![bg](assets/hero.svg)
# The best way to give a talk.
Now on every Mac.

Pillars block:

<!-- _class: pillars -->
#### What makes it work
## Three things.

<div class="columns">
<div>

### Fast
Opens before you sit down.

</div>
<div>

### Quiet
No fans. No noise. Ever.

</div>
<div>

### Yours
Every setting, on every device.

</div>
</div>

Blank lines inside the <div>s matter: they let Markdown render inside HTML. Keep them.

Other directives you may use: <!-- _paginate: false --> on a slide, ![bg right:40%](…) for a half-image slide, ![w:800](…)/![h:400](…) for a sized inline image, <!-- _color: … --> only on an image slide whose picture is light. Nothing else; no inline styles, no other HTML.

4. Art: art.mjs, offline, in seconds

Every deck gets art. All of it is generated into assets/ from the toolchain, deterministic from a seed, no network, no accounts:

# wallpapers: gradient light on black (or --light). Palettes: aurora sunset ocean graphite spectrum
"$MARP_TOOLCHAIN/art" wallpaper -o assets/hero.svg --palette aurora --seed 7
"$MARP_TOOLCHAIN/art" wallpaper -o assets/reveal.svg --palette aurora --seed 12

# a chart from the talk's real numbers: bar (default) or line, in the accent colour
"$MARP_TOOLCHAIN/art" chart -o assets/growth.svg --data "2023:12,2024:31,2025:64" --label "Teams on it" --type bar

# a screenshot or photo in a device, on a wallpaper: phone (default), laptop, window
"$MARP_TOOLCHAIN/art" frame -o assets/demo.svg --image assets/screen.png --kind laptop --palette ocean

• Same palette across the deck; vary --seed so slides differ. Seeds 1–99 all look good.
• Charts only from numbers in the talk; never decorate. Four to six points, label the axis in words (--label). Add --light for keynote-light.
• Frames want a real image in assets/ (PNG, JPG, WebP, SVG). Ask the user for the screenshot if the talk shows a product and none is there; use a wallpaper image slide until it arrives.
• Never reference an image that is not in the workspace. The check fails the deck.

5. The check

"$MARP_TOOLCHAIN/check"            # deck.md
"$MARP_TOOLCHAIN/check" other.md   # another file

Writes .harness/verdict.json (what the pane header shows) and prints every finding. Errors: the deck does not render, a slide is empty, an image is missing. Warnings: over 40 words on a slide, no image anywhere in the deck, no heading on the first slide, fewer than three slides, no marp: true. Ready = no errors and at least three slides. Polish = no warnings either. The viewer runs the same check on every save; run it yourself to read the list.

6. Export

"$MARP_TOOLCHAIN/marp" deck.md --theme-set "$MARP_THEMES" --allow-local-files --no-stdin -o dist/deck.pdf
"$MARP_TOOLCHAIN/marp" deck.md --theme-set "$MARP_THEMES" --allow-local-files --no-stdin -o dist/deck.pptx
"$MARP_TOOLCHAIN/marp" deck.md --theme-set "$MARP_THEMES" --allow-local-files --no-stdin -o dist/deck.html

--theme-set is what makes the keynote themes real outside the viewer; without it the export falls back to the default theme. PDF and PPTX render through a Chromium-family browser — the machine's, or the headless one setup fetched when it had none; toolchain/doctor.sh says which. HTML needs nothing. --no-stdin matters in a tool shell. Keynote (the app) opens the PPTX.