` — Pagefind UI mounts into it | Empty when `search: false` in config (Pagefind skipped). Populated otherwise. |
| `{{ themeToggle }}` | Dark/light toggle button | Always rendered. |
| `{{ pageActions }}` | "View / Copy as Markdown" buttons | Empty when `llmsButtons: false`. |
## Per-page text
HTML-escaped — safe to interpolate into attributes.
| Token | Source |
| --- | --- |
| `{{ title }}` | Page title (frontmatter `title` → first H1 → file ID) |
| `{{ description }}` | Effective description (frontmatter `description` → `config.description` → empty). Safe to drop into a `` in your layout — Markbook detects it and skips its own so the tag isn't duplicated. |
| `{{ siteTitle }}` | `config.title` (empty if unset) |
| `{{ browserTitle }}` | Effective `` value — `${pageTitle} — ${siteTitle}`, collapsed to just one when the page title already equals the site title |
## Arbitrary frontmatter
| Token | Substitutes |
| --- | --- |
| `{{ frontmatter.<dot.path> }}` | Any frontmatter field via dot-path (HTML-escaped). Missing paths render as empty string. |
```yaml
---
author:
name: Tudor
url: https://example.com
---
```
```html
{{ frontmatter.author.name }} ← "Tudor"
{{ frontmatter.author.url }} ← "https://example.com"
{{ frontmatter.author }} ← JSON-stringified object
{{ frontmatter.missing }} ← ""
```
## Validation rules
All throw at build time:
- **Missing `{{ content }}`** — `HTML layout 'X' is missing a {{ content }} placeholder.`
- **Duplicate `{{ content }}`** — `HTML layout 'X' has N {{ content }} placeholders. Exactly one is allowed.`
- **Unknown placeholder name** — `HTML layout 'X' uses unknown placeholder {{ tilte }}.` (typo guard)
- **Named layout not found** — `HTML layout 'landing' not found in: <searched dirs>.` (no silent fallback to built-in shell)
## HTML comments are preserved verbatim
Placeholders inside `<!-- ... -->` are NOT substituted, and the comments make it to the output unchanged. Useful for documenting the layout's vocabulary inline:
```html
<!--
Layout placeholders used here:
{{ content }} — rendered page body (REQUIRED)
{{ head }} — Markbook-required <head> bits (keep)
{{ bodyEnd }} — Markbook-required body-end scripts (keep)
{{ search }} — Pagefind search input slot
{{ themeToggle }} — dark/light toggle button
-->
```
## Minimal valid layout
```html
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>{{ browserTitle }}
{{ head }}
{{ pageActions }}
{{ content }}
{{ bodyEnd }}