How to Make On-Brand PowerPoint Decks with Copilot Cowork and a DESIGN.md File

To get an on-brand PowerPoint deck from Copilot Cowork, attach a DESIGN.md file that describes your brand, attach the content you want in the deck, and ask Cowork to build the presentation following the design file. In my demo it came back a minute or two later with my colours, fonts and logos in place, and no design touch-ups needed.

“How do we get Copilot to follow our brand in PowerPoint?” keeps coming up with organisations, and this is the approach I’ve been teaching them. The brand lives in the design file and the content comes from your transcripts or notes, so the same file carries over to other decks and documents. If Cowork is new to you, start with my Copilot Cowork tutorial.

What is a DESIGN.md file?

DESIGN.md is an open format from Google Labs, released under the Apache 2.0 licence and still in alpha, for describing a design system to AI agents in one file. Design tokens sit in YAML at the top (hex colours, typography, spacing, corner rounding), and the markdown body explains how to use them in sections such as Colors, Typography, Layout, Components and Do’s and Don’ts. The spec is on GitHub.

It was written with Google’s Stitch design tool and coding agents in mind, but it’s plain markdown, so Cowork reads it fine. For decks I add the slide patterns I want, such as how title slides, highlight boxes and callouts should look, alongside the colours and fonts.

What do you need before you start?

• A Microsoft 365 Copilot licence with Cowork turned on. Cowork has been generally available since 16 June 2026 and was in the Frontier preview when I recorded this. Every run spends Copilot Credits.
• A DESIGN.md file for your brand. If you don’t have one, the interview steps further down will get you one.
• The content for the deck. Mine was transcripts from a course I’m building: the introduction, then expectations and outcomes.

How do you build the deck in Cowork?

1. Attach the design file. Drag your DESIGN.md file into the Cowork chat box, or choose Add attachments.
2. Attach the content. Drag in the source files. Cowork lists everything you’ve given it in the input folder on the right of the screen.
3. Write the prompt. I dictated mine: create a PowerPoint presentation from the outline of the new course I’ve given you, follow the design MD file when creating the deck, and use all the content from the transcripts.
4. Send it and leave it. Treat Cowork like a colleague you’ve delegated to: hand the job over and get on with something else. In my demo it brought in its built-in PowerPoint skill on its own because the job was a deck.
5. Open the deck. The file appears in the Output folder, where you can download it, open it in PowerPoint or open the folder it was saved in.

Type / in the chat box to see the skills Cowork can use, built-in and custom.

The deck followed the design file closely: my colours and fonts throughout, the logos at the top, and the boxes and highlights I’d described for content slides. Because the brand lives in the file, every deck I build from it should come out in the same colours, fonts and style. Swapping design files works the same way for HTML reports, which I showed in building a dashboard with Copilot Cowork.

How do you write a DESIGN.md file if you don’t have one?

Get the AI to interview you. You can run this prompt in Cowork or any capable AI chat. Mine, lightly tidied:

I want you to interview me, please, because I want to create a custom DESIGN.md file. Ask me the required questions one by one, and get enough information from me so that you can generate a DESIGN.md file based on my responses.

In my demo it started by asking what the brand was for (personal brand and consulting) and kept asking, one question at a time, until it had enough to write the file. Have your hex codes, font names and logo files handy before you start, because those are the answers it needs exactly.

How do you turn the workflow into a Cowork skill?

1. Stay in the task where you built the deck, so Cowork has the design file and what it learned in context.
2. Ask for the skill. My prompt: create a skill so I don’t have to upload this DESIGN.md file over and over again. Incorporate the design file, perhaps in a references folder the skill can call on, and always use it when creating a PowerPoint presentation.
3. Let the Skill management skill do the build. It’s the built-in Cowork skill for creating and managing skills, and it writes the SKILL.md, validates it and saves it.

Custom skills are saved to your OneDrive under Documents/Cowork/skills, one folder per skill, and you’ll find yours under Customize, then the Skills tab. A packaged skill can carry companion files like the design file, as long as SKILL.md sits at the root of the package.

Keep one design file, and put it where your team can find it

The design file is now part of your brand, so I’d treat it that way. Mine came out of my Downloads folder for the demo, which is fine for one person testing an idea. For a team, store it in a SharePoint library with a named owner, version history on, and edit rights limited to whoever looks after the brand. Everyone else reads it.

Then decide how people get it. A personal skill is the quickest route for you, and you can share a Cowork skill with specific people from its detail page, choosing Re-share each time the brand changes. If your organisation builds agents in Agent Builder too, I’d keep the design rules as a separate skill that other skills load, which is how my executive dashboard skill picks up a shared editorial design skill in adding skills to Copilot agents.

Keep the design file about design. Content guidance, such as tone or what goes on a title slide for a client proposal, belongs in the prompt or a separate skill, so the design file can be reused for reports, one-pagers and HTML pages without dragging deck-specific rules along.

What to watch for

• Check every slide before it goes out. Cowork writes the slide content from your sources as well as styling it, so read each slide against the transcripts or notes it came from.
• Two copies of the brand. Once the design file is packaged in a skill, the skill holds its own copy, so update both when the colours or fonts change.
• Credits. Every run spends Copilot Credits, so type /cost when a deck finishes to see what it used.

Frequently asked questions

Is DESIGN.md a Microsoft feature? No. It’s an open format from Google Labs, and Cowork reads it because it’s markdown. Nothing in Cowork requires that format.

How big can a Cowork skill with a design file be? A single skill file can be up to 1 MB. A zipped skill package, with SKILL.md at its root and companion files such as the design file, can be up to 10 MB compressed, 50 MB uncompressed and 100 files.

Can I use my existing PowerPoint template instead? In my demo I gave Cowork no PowerPoint template, only the design file, and it built the brand from that. Copilot in PowerPoint works the other way: it applies your branded .potx or .pptx templates, which admins can publish to an organisation assets library in SharePoint.