# File format
A built deck is one HTML5 file. Everything it needs to render is inside it: the JavaScript, the CSS, the fonts, and the slide assets. Nothing loads from disk or over the network when the page opens. This page describes how that file is laid out so you can inspect it, diff it, or read its embedded data from your own tooling.
For how to produce the file and where to put it, see [Building & deploying](https://docs.liebstoeckel.app/guides/building/). This page is the format itself.
## Document structure
The file is a complete HTML document. Open it and you'll find roughly this shape:
```html
Your deck title
```
A few things are worth calling out:
- **One module script holds the whole app.** The engine, your slides, and any plugins' client code are bundled and minified into a single `
```
The pack respects your `package.json` `files` allowlist (or `.npmignore` / `.gitignore`), and never includes `node_modules`, `dist`, or `.git`. A build-time secret gate refuses to embed a `.env` or any file matching a credential signature, so this block should not leak secrets. For a smaller, opaque file with no recoverable source, build with `--no-inline-package`.
Turn the file back into a project with [`liebstoeckel eject`](https://docs.liebstoeckel.app/reference/cli/#eject):
```bash
liebstoeckel eject my-talk.html ./my-talk
```
**Caution:** Ejecting writes files from whatever HTML you hand it. `eject` validates archive paths and caps the decompressed size, but it never runs install or build scripts for you. Treat an untrusted deck like any other untrusted archive.
### Thumbnail manifest
If a headless Chromium was available at build time, the file carries one small WebP image per slide as a data URI, used to draw the overview grid without rendering every slide live:
```json
{
"v": 1,
"w": 640,
"h": 360,
"thumbs": { "0": "data:image/webp;base64,...", "1": "data:image/webp;base64,..." }
}
```
Thumbnails are optional. The build skips them, with a note rather than an error, when no Chromium is found or when you set `LIEBSTOECKEL_NO_THUMBS=1`. Without the manifest the overview falls back to rendering slides directly. See [Thumbnails](https://docs.liebstoeckel.app/guides/thumbnails/).
## Standalone and live from the same file
The file does not contain a relay URL or a session token, and it makes no network requests on its own. Opened from disk or a static host, it runs entirely offline: plugins show their `fallback`, and the presenter view works through the browser's `BroadcastChannel`.
The same file goes live without rebuilding. When you serve it with [`liebstoeckel live`](https://docs.liebstoeckel.app/guides/live/), the server injects a small bootstrap script ahead of the bundle. That script connects to a relay over a Yjs document, and from then on plugins instantiate their server bundles and sync state across the room. Because the live wiring is injected at serve time and not baked into the file, the exact same `.html` you email still opens standalone.
[Building & deploying](https://docs.liebstoeckel.app/guides/building/)
[CLI reference](https://docs.liebstoeckel.app/reference/cli/)