The round trip

Count the conversions

Idea

—

.pptx

boxed into a rectangle

Their projector

fonts substitute

Export to PDF

animation flattens

Screenshot

links die

Someone’s phone

unreadable

Five conversions between the thought and the person. Each one is lossy, and none of them are steps you chose — they’re the tax on having picked a file format as your output. The embedded video never travels. It never has.

Ask for what it’s good at

Same slide title, two formats

.pptx — a zip of XML

<p:sp> <p:nvSpPr> <p:cNvPr id="2" name="Title 1"/> </p:nvSpPr> <p:spPr><a:xfrm> <a:off x="838200" y="365125"/> <a:ext cx="10515600" cy="1325563"/> </a:xfrm></p:spPr> <p:txBody><a:p><a:r> <a:t>Generate the medium</a:t> </a:r></a:p></p:txBody> </p:sp>

Coordinates in English Metric Units. Written blind — the model can’t open it and look.

HTML — the medium itself

<h1 class="slide-title"> Generate the medium </h1>

Renders instantly. You can see it, so the agent can be told it’s wrong.

You can generate .pptx — the libraries exist. But you’re asking a model to write a format it cannot open and judge, so the feedback loop is broken before it starts. HTML and CSS are the best‑represented things in its training data by a wide margin. And you don’t have to write this — only read enough of it to say “that’s wrong.”

The final medium

One arrow

IDEA

no conversion

THE SCREEN

The medium your audience actually receives is a rendered page. Generate that and there is nothing left in between to lose anything. Live data stays live. Links stay links. The whole deck is one HTTP request.

Honest ledger

What you gain, what you give up

Gained

No licence, no “created in a newer version”

No font substitution — the fonts ship with the page

Opens on anything with a browser

Deployable to a URL, diffable in git

The slide can run things

Given up

Corporate template compliance — no answer. Sometimes you lose this one.

A file a colleague can edit in PowerPoint — they edit the page instead

Animation by menu — you describe it instead

Needs a browser, and a network for the live parts — PDF export covers the room with no wifi

Most of the right‑hand column has an answer, and I’ll show you the PDF export later. But the first one doesn’t. If your organisation mandates the corporate template, this is a fight you may not win — take the design‑system idea from the next section and leave the HTML behind. It works on its own.