Slide Deck Design skill for Codex

A deck works when a busy reader who reads only the slide titles, in order, gets the full argument, and every slide body proves its own title. Visual polish comes after that, and only serves legibility.

Workflow

- [ ] 1. Pin down audience, decision and setting
- [ ] 2. Write the one-sentence answer
- [ ] 3. Build the storyline as a title-only outline
- [ ] 4. Pick the evidence for each slide
- [ ] 5. Choose the build tool and apply the layout system
- [ ] 6. Run the review checks
- [ ] 7. Hand over with speaker notes and an appendix

1. Audience, decision, setting

Ask or infer before writing a single slide:

Question	Why it changes the deck
Who decides, and what do they already believe?	Sets how much context and which objections to pre-empt
What should they do or decide afterwards?	The deck exists for this; if there is no ask, it is an update, say so
Presented live or read alone (pre-read, emailed)?	Live: sparse slides plus notes. Read alone: full-sentence titles and denser bodies
Time slot?	Roughly one main slide per 1 to 2 minutes live; everything else goes to the appendix
Brand template or house style?	Check the repo or shared drive for a .potx/theme and AGENTS.md notes before inventing one

2. Write the answer first

One sentence the decision-maker could repeat to their boss, for example: “Moving EU traffic to the Frankfurt region cuts p95 latency by 40% for 18k a year, and we need approval by 1 December to hit Q1.”

If you cannot write it, the deck is not ready to design. Go back to the source material.

3. Storyline as a title-only outline

Default structure for a decision deck (situation, complication, resolution, then proof):

1. Title slide states the answer or the ask, not just the topic.
2. Situation: what the audience already accepts (1 slide).
3. Complication: what changed or what is at risk, with one number (1 to 2 slides).
4. Resolution: the recommendation and the ask (1 slide).
5. Supporting arguments, one per slide, each a claim with evidence (3 to 6 slides).
6. Risks, costs and alternatives considered (1 to 2 slides).
7. Next steps with owners and dates (1 slide).
8. Appendix: methodology, detail tables, backup charts.

Variants:

Deck type	Shape
Status update	Headline status, what changed since last time, risks and asks, then detail
Conference talk	Problem the audience has, the insight, 3 demonstrations, what to do Monday
Sales/pitch	Customer’s problem in their words, cost of the problem, approach, proof, offer
Training	Outcome, then concept-example-practice loops

Write every title as an action title: a full sentence with the takeaway, at most two lines. “Q3 revenue” is a label; “Q3 revenue grew 12%, driven by annual plans” is a title.

Produce the outline as a table before building anything:

| # | Action title | Evidence on slide | Notes |
|---|---|---|---|
| 1 | Move EU traffic to Frankfurt to cut latency 40% for 18k/yr | Ask + date | Title slide |
| 2 | EU users are now 46% of sessions, up from 20% | Line chart, share by region | Situation |
| 3 | Their p95 latency is 2.3x US users' and churn tracks it | Bar chart + churn callout | Complication |

Read the titles aloud in sequence. If the argument has a gap or repeats itself, fix the outline, not the visuals.

4. Evidence per slide

One message per slide, and the body must prove the title. Pick the element by message:

Message	Use	Avoid
Change over time	Line chart, highlight the relevant series	3D, more than 5 lines
Compare items	Horizontal bar, sorted	Pie with more than 3 slices
Part of whole	Stacked bar or a single big number	Donut grids
One striking number	Big number with a one-line comparison	Number without baseline
Process or sequence	3 to 5 step flow, left to right	Smart-art with 9 bubbles
Before/after or options	Two-column comparison, same rows on both sides	Asymmetric columns
Quote or customer voice	Short quote with attribution	Wall of testimonials

Chart rules: label lines directly instead of a legend, put the takeaway in the title and mark it on the chart (colour or annotation), start bar axes at zero, state units and source in a small footer, remove gridlines and borders that carry no data.

5. Layout system and build tool

Layout defaults for a 16:9 deck (13.333 x 7.5 in, 1920 x 1080 px):

• Margins at least 0.5 in (about 5% of width) on every side; content never touches edges.
• Type: titles 28 to 40 pt, body 18 to 24 pt, footnotes and sources no smaller than 12 pt. For a large room, body text at 24 pt or more.
• At most 2 typefaces; use weight and size for hierarchy, not new fonts.
• Colour: one neutral for text, one accent for “look here”, one muted for context. Body text contrast at least 4.5:1 against the background.
• Same element, same position on every slide (title, source line, page number), so the eye only tracks what changes.
• About 6 bullet lines maximum, each one line long. More than that becomes a document slide: split it or move it to the appendix.
• Alignment: everything snaps to a grid; left-align text blocks; do not centre paragraphs.

Pick the build tool:

Situation	Tool
Stakeholders edit in PowerPoint, brand .potx exists	python-pptx with the template’s layouts (see pptx-presentations)
Team lives in Google Workspace	Slides API with a template copy (see google-docs-automation)
Engineer audience, slides in git, code samples	Marp (Markdown) or Slidev (Markdown + Vue)
Interactive web talk, embedded demos	reveal.js
Must be emailed as a fixed file	Any of the above, exported to PDF

Marp example (one slide per ---; export needs @marp-team/marp-cli, which needs network to install):

---
marp: true
paginate: true
size: 16:9
---

# EU users now drive 46% of sessions

![w:900](charts/sessions-by-region.svg)

<!-- Speaker notes: mention that the growth came after the DE launch. -->

npx @marp-team/marp-cli deck.md --pdf --allow-local-files
npx @marp-team/marp-cli deck.md --pptx    # each slide becomes an image, not editable text

Generate charts as SVG or high-DPI PNG from code (matplotlib savefig(dpi=200)) at the size they will appear, so text inside charts matches slide typography.

6. Review checks

Run these before calling it done:

• Title read-through: titles alone tell the full story in order.
• So-what test: each slide’s body supports its title; delete anything that does not.
• Squint test: render to images and view small; the most important element per slide should still stand out.
• Number check: every figure matches the source; the same metric uses the same units and rounding on every slide.
• Legibility: no text below 12 pt, no text over busy photos without a scrim, colour is never the only cue (add labels or patterns).
• Overflow: no text box spilling past margins; check every slide image, not a sample.

To render slides as images for review (needs LibreOffice for pptx):

soffice --headless --convert-to pdf deck.pptx
pdftoppm -r 50 -png deck.pdf review/slide     # poppler; small thumbnails for the squint test

7. Hand over

Speaker notes on every main slide carry what the presenter says and the details cut from the slide. The appendix holds methodology and backup data, referenced from main slides as “see A3”.

Gotchas

• Topic titles (“Background”, “Findings”) hide the argument; replace every one.
• Decks written as documents fail live, and decks built for live delivery fail as pre-reads. Ask which one it is.
• Agenda slides for short decks waste a slot; use one only above roughly 15 slides.
• Logos, page numbers and confidentiality footers repeated at large size eat 15% of space.
• Animations: use builds only to reveal a sequence in order; never decorative transitions.
• Pasted screenshots of tables are unreadable; rebuild the 3 to 5 rows that matter.

Output

Deliver the outline table (step 3), the deck file, and a short note:

## Deck: eu-region-proposal.pptx (12 main slides + 5 appendix)
- One-sentence answer: <the answer>
- Audience/setting: infra steering group, presented live, 20 min
- Checks: title read-through ok, numbers reconciled to capacity-model.xlsx, all text >= 14 pt
- Open questions: cost estimate assumes 2026 list prices (slide 8)