# One design for three language editions

> One booklet in English, Spanish and Arabic from a single set of general settings, with an override for what belongs to each language: faces, sizes, tracking.

- HTML version: https://postext.dev/en/cookbook/shared-design-per-language
- Recipe Nº 178 · Output & integration · Level 3 (Advanced) · Outputs: Canvas, PDF
- Genres: Catalogues
- Requires postext ≥ 1.65.0, postext-pdf ≥ 1.65.0 · tested with 1.65.0, postext-pdf 1.65.0 on 2026-10-31
- Pages: [1](https://postext.dev/cookbook/shared-design-per-language/en/p01.webp?v=215986b8), [2](https://postext.dev/cookbook/shared-design-per-language/en/p02.webp?v=215986b8), [3](https://postext.dev/cookbook/shared-design-per-language/en/p03.webp?v=215986b8), [4](https://postext.dev/cookbook/shared-design-per-language/en/p04.webp?v=215986b8)
- PDF: https://postext.dev/cookbook/shared-design-per-language/en/shared-design-per-language.pdf?v=215986b8
- Open in Sandbox: https://postext.dev/en/sandbox#recipe=shared-design-per-language&lang=en (.postext: https://postext.dev/cookbook/shared-design-per-language/en/shared-design-per-language.postext)
- Last updated: 2026-10-31
- Other languages: [es](https://postext.dev/es/cookbook/shared-design-per-language.md), [ca](https://postext.dev/ca/cookbook/shared-design-per-language.md), [de](https://postext.dev/de/cookbook/shared-design-per-language.md), [fr](https://postext.dev/fr/cookbook/shared-design-per-language.md), [it](https://postext.dev/it/cookbook/shared-design-per-language.md), [pt](https://postext.dev/pt/cookbook/shared-design-per-language.md), [zh](https://postext.dev/zh/cookbook/shared-design-per-language.md), [ja](https://postext.dev/ja/cookbook/shared-design-per-language.md), [ar](https://postext.dev/ar/cookbook/shared-design-per-language.md)

## In short

A small booklet about three old astrolabes, printed in English, Spanish and Arabic. All three share one design; only the Arabic edition changes its fonts and sizes.

## What you'll build

A booklet of four A5 pages on three astrolabes in the Metropolitan Museum of Art: one made in Yemen in 1291, one in Iran in 1654 and one in Europe in 1462. The publisher prints it in English, Spanish and Arabic, and the three editions are one design. The cover photograph, the brass headings, the box with its stripe, the figures with the text beside them and the dark table header come from a single set of settings. The Arabic edition changes what belongs to its script: Amiri and IBM Plex Sans Arabic for Source Serif and Source Sans, a larger size, and labels without capitals or tracking. It reads from the right and binds on the right without one coordinate of its own.

**This recipe answers:**

- How do I share one design between the editions of a book and change only each language's fonts and labels?
- How do I publish the same book in two languages from one project?

## The short answer

What each language sets otherwise; the rest comes from the general settings.

```js
// script.js, lines 114–141
const ARABIC_LABEL = { fontFamily: 'IBM Plex Sans Arabic', letterSpacing: pt(0),
  textTransform: 'none' }; // Arabic letters join: never tracked, and they have no capitals
// English and Spanish need nothing more than their locale: it picks the hyphenation patterns
// and the words of the figure and table labels. Arabic sets the faces of its script.
const overrides = {
  ar: {
    bodyText: { fontFamily: 'Amiri', fontSize: pt(12), lineHeight: pt(19),
      firstLineIndent: em(1.5) },
    headings: { fontFamily: 'Amiri', fontWeight: 700,
      levels: [{ level: 2, fontSize: pt(15), lineHeight: pt(24) }] },
    // Lists keyed by id merge entry by entry: only these fields of these elements change.
    headingStyles: [{ id: 'cover', advancedDesign: { slot: { elements: [
      { id: 'kicker', ...ARABIC_LABEL, fontSize: pt(10) },
      { id: 'title', fontFamily: 'Amiri', fontWeight: 700, fontSize: pt(50), lineHeight: 1.25 },
      { id: 'facts', ...ARABIC_LABEL, fontSize: pt(9.5) },
    ] } } }],
    header: { elements: ['verso-folio', 'verso-title', 'recto-title', 'recto-folio']
      .map((id) => ({ id, ...ARABIC_LABEL, fontSize: pt(9) })) },
    calloutStyles: [{ id: 'note', titleStyle: { ...ARABIC_LABEL, fontSize: pt(10) },
      body: { fontSize: pt(11.5), lineHeight: pt(19) } }],
    tableStyle: { headerFontFamily: 'IBM Plex Sans Arabic', headerFontSize: pt(9),
      bodyFontFamily: 'IBM Plex Sans Arabic', bodyFontSize: pt(9.4) },
    captionStyle: { fontFamily: 'IBM Plex Sans Arabic', fontSize: pt(9) },
    paragraphStyles: [{ id: 'colophon', fontFamily: 'IBM Plex Sans Arabic', fontSize: pt(8.4),
      lineHeight: pt(13) }],
  },
};
const edition = mergeConfigLayers(config, overrides[LANG]); // config itself for en and es
```

## Ingredients

**Teaches**

- [Per-language overrides](https://postext.dev/en/docs/configuration-bundles.md#general-settings-and-per-language-overrides): The editions of a book share one set of general settings, and each language overrides only what belongs to it, such as the typefaces of its script, its hyphenation, quotes or labels; the override merges field by field.

**Also uses**

- [Right-to-left text](https://postext.dev/en/docs/arabic-layout.md#direction-and-the-bidirectional-algorithm)
- [Arabic fonts](https://postext.dev/en/docs/arabic-layout.md#fonts)
- [Books bound on the right](https://postext.dev/en/docs/configuration-page-layout.md#binding)
- [Digits of the generated numbers](https://postext.dev/en/docs/configuration-language.md#document-language)
- [Hyphenation and document language](https://postext.dev/en/docs/justification.md#supported-locales)
- [Figure and Table in your language](https://postext.dev/en/docs/configuration-resources.md#resource-types)
- [Covers, title pages and colophons](https://postext.dev/en/docs/configuration-styles.md#heading-styles)
- [Heading styles](https://postext.dev/en/docs/configuration-styles.md#heading-styles)
- [Heading attributes](https://postext.dev/en/docs/document-format.md#heading-attributes)
- [Pictures in page designs](https://postext.dev/en/docs/configuration-headers-footers.md#image-elements)
- [Running heads and folios](https://postext.dev/en/docs/configuration-headers-footers.md#headers--footers)
- [Text wrap round pictures and boxes](https://postext.dev/en/docs/document-format-resources.md#text-wrap)
- [Callout boxes](https://postext.dev/en/docs/configuration-callouts.md#callout-styles)
- [Table style](https://postext.dev/en/docs/configuration-resources.md#table-style)
- [Caption style](https://postext.dev/en/docs/configuration-resources.md#caption-style)
- [Semantic colour palette](https://postext.dev/en/docs/configuration-fonts-colors-viewers.md#color-palette)
- [PDF export](https://postext.dev/en/docs/configuration-pdf-output.md#generating-pdfs)
- [Figures exactly here](https://postext.dev/en/docs/document-format-resources.md#block-embed-optional-explicit-inline-placement)
- [Full-width chapter band](https://postext.dev/en/docs/configuration-headings.md#span-and-advanced-design)
- [Designed openers](https://postext.dev/en/docs/configuration-headings.md#span-and-advanced-design)
- [Heads by page role](https://postext.dev/en/docs/configuration-headers-footers.md#text-elements)
- [Paragraph styles](https://postext.dev/en/docs/configuration-styles.md#paragraph-styles)
- [Fonts embedded in the PDF](https://postext.dev/en/docs/configuration-pdf-output.md#why-a-font-provider)
- [Figures and tables as resources](https://postext.dev/en/docs/document-format-resources.md#resources)
- [Line breaks in titles](https://postext.dev/en/docs/document-format-directives.md#line-breaks-in-titles)

**Config at a glance**

- [`bodyText`](https://postext.dev/en/docs/configuration-text.md#body-text), [`calloutStyles`](https://postext.dev/en/docs/configuration-callouts.md#callout-styles), [`captionStyle`](https://postext.dev/en/docs/configuration-resources.md#caption-style), [`colorPalette`](https://postext.dev/en/docs/configuration-fonts-colors-viewers.md#color-palette), [`footer`](https://postext.dev/en/docs/configuration-headers-footers.md#headers--footers), [`header`](https://postext.dev/en/docs/configuration-headers-footers.md#headers--footers), [`headingStyles`](https://postext.dev/en/docs/configuration-styles.md#heading-styles), [`headings`](https://postext.dev/en/docs/configuration-headings.md#headings), [`layout`](https://postext.dev/en/docs/configuration-page-layout.md#layout), [`locale`](https://postext.dev/en/docs/configuration-language.md#hyphenation), [`page`](https://postext.dev/en/docs/configuration-page-layout.md#page), [`paragraphStyles`](https://postext.dev/en/docs/configuration-styles.md#paragraph-styles), [`tableStyle`](https://postext.dev/en/docs/configuration-resources.md#table-style)

**APIs**

- [`buildDocument`](https://postext.dev/en/docs/configuration-programmatic-usage.md#building-a-document), [`decompressWoff2`](https://postext.dev/en/docs/configuration-pdf-output.md#browser-font-provider-fontsource--woff2), `mergeConfigLayers`, [`registerResourceImage`](https://postext.dev/en/docs/architecture.md#api-surface), [`renderPageToCanvas`](https://postext.dev/en/docs/configuration-programmatic-usage.md#rendering-a-page-to-a-bitmap), [`renderToPdf`](https://postext.dev/en/docs/configuration-pdf-output.md#generating-pdfs), [`withLoadedFonts`](https://postext.dev/en/docs/configuration-programmatic-usage.md#loading-fonts-before-layout)

**Typefaces**

- Source Serif 4 (OFL-1.1), Source Sans 3 (OFL-1.1), Amiri (OFL-1.1), IBM Plex Sans Arabic (OFL-1.1)

## Method

### 1 · General settings and three small overrides

The code is [the short answer](https://postext.dev/en/cookbook/shared-design-per-language.md#the-short-answer) above. `config` holds the general settings; `mergeConfigLayers` lays an edition's override over them field by field. English and Spanish have no override: their `locale` picks the hyphenation patterns and the words *Figure* and *Table*, *Figura* and *Tabla*. The Arabic override names only fields: `bodyText.fontFamily` changes the face and keeps the colour, the alignment and the hyphenation setting, and the cover's `kicker` element changes its face and tracking and keeps its anchor, colour and size of box. A change to the palette or the margins in `config` reaches all three editions.

### 2 · Sides named by the direction of the text

```js
// script.js, lines 59–72
// An even page's outer edge is its start side in either direction (the left of an English
// verso, the right of an Arabic one), an odd page's its end side.
const head = (id, content, parity, edge, x, extra = {}) => ({ kind: 'text', id, content,
  parity, pages: 'body', fontFamily: LABEL, fontSize: pt(7.5), fontWeight: 600,
  letterSpacing: pt(1.1), textTransform: 'uppercase', color: col('muted'),
  align: edge.endsWith('start') ? 'start' : 'end',
  placement: { anchor: { to: 'page', edge }, offset: { x: mm(x), y: mm(12) } }, ...extra });
const folio = { fontWeight: 700, color: col('brass') };
const header = { elements: [
  head('verso-folio', '{pageNumber}', 'even', 'top-start', 16, folio),
  head('verso-title', '{title}', 'even', 'top-start', 24),
  head('recto-title', '{subtitle}', 'odd', 'top-end', -24),
  head('recto-folio', '{pageNumber}', 'odd', 'top-end', -16, folio),
] };
```

An even page's outer edge is the start of its lines in both directions, and an odd page's is the end, so `top-start` and `top-end` put the folios outside on an English verso and on an Arabic one. The box stripe is `side: 'start'` and the cover's text is anchored to `top-start`: none of them needs an override.

### 3 · Figures wrapped at the end of the line

```js
// script.js, lines 195–219
const photo = (id, file, w, h, extra = {}) => ({ id, typeId: 'figure', kind: 'bitmap',
  createdAt: 0, updatedAt: 0, ...extra,
  bitmap: { fileId: file, format: 'jpeg', width: w, height: h } });
// 'end' is the right of an English column and the left of an Arabic one.
const wrapped = { position: 'here', wrap: 'end', width: 0.38 };
const note = (n) => `The Met, ${n}, CC0`;
const resources = [
  photo('rasulid', 'rasulid-cover-1400.jpg', 1400, 1985),
  photo('mashhad', 'mashhad-800.jpg', 800, 1187, { placement: wrapped, note: note('63.166a–j'),
    caption: t({ en: 'Planispheric astrolabe, Iran, 1654–55. Brass and steel.',
      es: 'Astrolabio planisférico, Irán, 1654-1655. Latón y acero.',
      ar: 'أسطرلاب مسطّح، إيران، ١٠٦٥\u00a0هـ / ١٦٥٤–١٦٥٥\u00a0م. نحاس أصفر وفولاذ.' }),
    altText: t({ en: 'A brass astrolabe whose rete is a lattice of leaves and scrolls',
      es: 'Un astrolabio de latón cuya red es un enrejado de hojas y volutas',
      ar: 'أسطرلاب من النحاس الأصفر عنكبوته شبكة من الأوراق والأغصان الملتفّة' }) }),
  photo('regiomontanus', 'regiomontanus-800.jpg', 800, 1083,
    { placement: wrapped,
    note: note('2025.347a–j'),
    caption: t({ en: 'Astrolabe attributed to Regiomontanus, 1462. Copper alloy.',
      es: 'Astrolabio atribuido a Regiomontano, 1462. Aleación de cobre.',
      ar: 'أسطرلاب يُنسب إلى ريجيومونتانوس، ١٤٦٢\u00a0م. سبيكة نحاسية.' }),
    altText: t({ en: 'A round brass astrolabe with Latin star names on its rete',
      es: 'Un astrolabio redondo de latón con nombres latinos de estrellas en la red',
      ar: 'أسطرلاب مستدير من النحاس عليه أسماء نجوم لاتينية' }) }),
];
```

`wrap: 'end'` puts each photograph on the right of an English column and on the left of an Arabic one, and the text runs beside it. The captions and alt texts come in each edition's language; the Arabic captions give the Hijri date first.

### 4 · The table in each edition's words and digits

```js
// script.js, lines 223–241
const row = (...cells) => cells.map((content) => ({ content }));
const head2 = (...cells) => cells.map((content) => ({ content, isHeader: true }));
resources.push({ id: 'three', typeId: 'table', kind: 'table', createdAt: 0, updatedAt: 0,
  placement: { position: 'here' },
  caption: t({ en: 'The three instruments.', es: 'Los tres instrumentos.',
    ar: 'الأدوات الثلاث.' }),
  table: { model: { headerRowCount: 1, columnWidths: [1.15, 1.1, 1.2, 1.1], rows: t({
    en: [head2('Made', 'Where', 'Maker', 'Size'),
      row('1291', 'Yemen', 'ʿUmar ibn Yūsuf', '15.6 cm wide'),
      row('1654–55', 'Iran, Mashhad?', 'Muhammad Zaman', '21.6 cm high'),
      row('1462', 'Germany or Italy', 'Regiomontanus', '13.5 cm high')],
    es: [head2('Fecha', 'Lugar', 'Autor', 'Tamaño'),
      row('1291', 'Yemen', 'ʿUmar ibn Yūsuf', '15,6 cm de ancho'),
      row('1654-1655', 'Irán, ¿Mashhad?', 'Muhammad Zaman', '21,6 cm de alto'),
      row('1462', 'Alemania o Italia', 'Regiomontano', '13,5 cm de alto')],
    ar: [head2('التاريخ', 'المكان', 'الصانع', 'المقاس'),
      row('٦٩٠\u00a0هـ / ١٢٩١\u00a0م', 'اليمن', 'عمر بن يوسف', 'عرضه ١٥٫٦\u00a0سم'),
      row('١٠٦٥\u00a0هـ / ١٦٥٤\u00a0م', 'إيران، مشهد؟', 'محمد زمان', 'ارتفاعه ٢١٫٦\u00a0سم'),
      row('١٤٦٢\u00a0م', 'ألمانيا أو إيطاليا', 'ريجيومونتانوس', 'ارتفاعه ١٣٫٥\u00a0سم')] }) } } });
```

The table's data is content, so it changes with the edition: Arabic-Indic digits and the Arabic decimal separator in the Arabic edition, a decimal comma in the Spanish one. Its style is general: the override only sets the Arabic face and size.

## The whole recipe

One file, composed from the recipe's folder with the sample text and the Cookbook's shared kit inlined; it builds its own page. To run it, put it in a `<script type="module">` on an empty page, or paste it into the JS panel of a new CodePen (as a module). It imports postext from esm.sh, so there is nothing to install or build.

- Source folder: https://github.com/drnachio/postext/tree/main/cookbook/shared-design-per-language

### script.js

```js
// ═══ Postext Cookbook · Nº 178 · One design for three language editions ═══════════
// https://postext.dev/en/cookbook/shared-design-per-language
// Code: MIT · Text: original (CC BY 4.0) · Photographs: The Met, Open Access (CC0)
// Fonts: Source Serif 4, Source Sans 3, Amiri, IBM Plex Sans Arabic (OFL) · Needs postext ≥ 1.65.0
import {
  buildDocument, withLoadedFonts, renderPageToCanvas, registerResourceImage, mergeConfigLayers,
} from 'https://esm.sh/postext';
import { renderToPdf, decompressWoff2 } from 'https://esm.sh/postext-pdf';

const LANG = 'en'; // @lang: the edition: 'en' | 'es' | 'ar'
const RECIPE = 'shared-design-per-language';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
// #region palette: night ink, the brass of the instruments, a parchment tint
const palette = {
  ink: '#1f2230', // text: a blue near-black
  brass: '#80561c', // the one accent: kickers, rules, the box stripe (6.2:1 on paper)
  tint: '#f4eee2', // the box ground
  rule: '#cfc5b2', // hairlines
  muted: '#6a655c', // running heads, credits
  paper: '#ffffff',
};
const col = (id) => ({ hex: palette[id], model: 'hex', paletteId: id });
const colorPalette = [
  ...Object.entries(palette).map(([id, hex]) => ({ id, name: id, value: { hex, model: 'hex' } })),
  { id: 'main-color', name: 'brass (defaults)', value: { hex: palette.brass, model: 'hex' } },
];
// #endregion
const [TEXT, LABEL] = ['Source Serif 4', 'Source Sans 3'];
const PAGE = { w: 148, h: 210 }; // mm: an A5 booklet
const LEAD = 14; // pt

// #region cover: the photograph to the trim, the title on its dark head
const at = (edge, x, y, width) => ({ anchor: { to: 'page', edge },
  offset: { x: mm(x), y: mm(y) }, ...(width ? { size: { width: mm(width) } } : {}) });
const caps = { fontFamily: LABEL, fontWeight: 700, textTransform: 'uppercase',
  letterSpacing: pt(1.6) };
// Every side is named by the direction of the text: 'top-start' is the left of an English
// page and the right of an Arabic one, so the cover needs no override to turn round.
const cover = { id: 'cover',
  advancedDesign: { enabled: true, slot: { elements: [
    { kind: 'image', id: 'photo', resourceId: 'rasulid', decorative: true, fit: 'cover',
      placement: { anchor: { to: 'page', edge: 'top-left' },
        size: { width: mm(PAGE.w), height: mm(PAGE.h) } } },
    { kind: 'text', id: 'kicker', content: '{attr.kicker}', fontSize: pt(8.5), align: 'start',
      color: col('paper'), ...caps, placement: at('top-start', 17, 18) },
    { kind: 'rule', id: 'rule', direction: 'horizontal', thickness: pt(1.5), color: col('tint'),
      placement: { anchor: { to: '#kicker', edge: 'below' }, offset: { x: mm(0), y: mm(3) },
        size: { width: mm(16) } } },
    { kind: 'text', id: 'title', content: '{titleText}', fontFamily: TEXT, fontWeight: 600,
      fontSize: pt(46), lineHeight: 1.02, color: col('paper'), align: 'start',
      placement: at('top-start', 16, 29, PAGE.w - 32) },
    { kind: 'text', id: 'facts', content: '{attr.facts}', fontSize: pt(8), align: 'start',
      color: col('ink'), ...caps, placement: at('bottom-start', 17, -14) },
  ] } } };
// #endregion

// #region heads: title on the verso, subtitle on the recto, folios on the outer edge
// An even page's outer edge is its start side in either direction (the left of an English
// verso, the right of an Arabic one), an odd page's its end side.
const head = (id, content, parity, edge, x, extra = {}) => ({ kind: 'text', id, content,
  parity, pages: 'body', fontFamily: LABEL, fontSize: pt(7.5), fontWeight: 600,
  letterSpacing: pt(1.1), textTransform: 'uppercase', color: col('muted'),
  align: edge.endsWith('start') ? 'start' : 'end',
  placement: { anchor: { to: 'page', edge }, offset: { x: mm(x), y: mm(12) } }, ...extra });
const folio = { fontWeight: 700, color: col('brass') };
const header = { elements: [
  head('verso-folio', '{pageNumber}', 'even', 'top-start', 16, folio),
  head('verso-title', '{title}', 'even', 'top-start', 24),
  head('recto-title', '{subtitle}', 'odd', 'top-end', -24),
  head('recto-folio', '{pageNumber}', 'odd', 'top-end', -16, folio),
] };
// #endregion

// The general settings: every edition reads them. Only the language is each edition's own.
const config = {
  locale: t({ en: 'en-gb', es: 'es', ar: 'ar' }), // ar: right to left, bound on the right
  colorPalette,
  page: { sizePreset: 'custom', width: mm(PAGE.w), height: mm(PAGE.h), dpi: 150,
    margins: { top: mm(21), bottom: mm(20), left: mm(18), right: mm(16), mirror: true } },
  bodyText: { fontFamily: TEXT, fontSize: pt(10), lineHeight: pt(LEAD), color: col('ink'),
    boldColor: col('ink'), italicColor: col('ink'), referenceColor: col('ink'),
    textAlign: 'justify', firstLineIndent: mm(4.5), indentAfterHeading: false,
    hyphenation: { enabled: true }, optimalLineBreaking: true,
    avoidWidows: true, avoidOrphans: true, avoidRunts: true },
  headings: { fontFamily: TEXT, color: col('ink'), fontWeight: 600, levels: [
    { level: 1, span: 'page', breakBefore: { parity: 'any' } }, // the cover, to the trim
    { level: 2, fontSize: pt(13), lineHeight: pt(LEAD * 1.25), color: col('brass'),
      marginTop: pt(LEAD), marginBottom: pt(LEAD * 0.25) },
  ] },
  headingStyles: [cover],
  layout: { layoutType: 'single', wrap: { gap: mm(5) } },
  paragraphStyles: [{ id: 'colophon', fontFamily: LABEL, fontSize: pt(7.4), lineHeight: pt(10),
    color: col('muted'), textAlign: 'start', firstLineIndent: pt(0), marginTop: pt(LEAD) }],
  // 'start': the stripe stands where the lines start, left in English, right in Arabic.
  calloutStyles: [{ id: 'note', background: col('tint'),
    stripe: { enabled: true, side: 'start', width: pt(3), color: col('brass') },
    padding: { top: mm(3), right: mm(4), bottom: mm(3.2), left: mm(4) },
    titleStyle: { fontFamily: LABEL, fontSize: pt(8), fontWeight: 700, letterSpacing: pt(1.1),
      textTransform: 'uppercase', color: col('brass') },
    body: { fontSize: pt(9.4), lineHeight: pt(13), firstLineIndent: pt(0) },
    marginTop: pt(LEAD * 0.5), marginBottom: pt(LEAD * 0.5) }],
  tableStyle: { rules: 'horizontal', borderColor: col('rule'), borderWidth: pt(0.5),
    headerBackground: col('ink'), headerColor: col('paper'), headerFontFamily: LABEL,
    headerFontSize: pt(7.8), bodyFontFamily: LABEL, bodyFontSize: pt(8.4), bodyColor: col('ink'),
    cellPadding: mm(1.4) },
  captionStyle: { fontFamily: LABEL, fontSize: pt(7.8), color: col('ink'), labelBold: true,
    labelColor: col('brass'), gap: mm(1.8), note: { color: col('muted'), fontSize: pt(6.8) } },
  header,
  footer: { elements: [] },
};

// #region answer: what each language sets otherwise; the rest comes from the general settings
const ARABIC_LABEL = { fontFamily: 'IBM Plex Sans Arabic', letterSpacing: pt(0),
  textTransform: 'none' }; // Arabic letters join: never tracked, and they have no capitals
// English and Spanish need nothing more than their locale: it picks the hyphenation patterns
// and the words of the figure and table labels. Arabic sets the faces of its script.
const overrides = {
  ar: {
    bodyText: { fontFamily: 'Amiri', fontSize: pt(12), lineHeight: pt(19),
      firstLineIndent: em(1.5) },
    headings: { fontFamily: 'Amiri', fontWeight: 700,
      levels: [{ level: 2, fontSize: pt(15), lineHeight: pt(24) }] },
    // Lists keyed by id merge entry by entry: only these fields of these elements change.
    headingStyles: [{ id: 'cover', advancedDesign: { slot: { elements: [
      { id: 'kicker', ...ARABIC_LABEL, fontSize: pt(10) },
      { id: 'title', fontFamily: 'Amiri', fontWeight: 700, fontSize: pt(50), lineHeight: 1.25 },
      { id: 'facts', ...ARABIC_LABEL, fontSize: pt(9.5) },
    ] } } }],
    header: { elements: ['verso-folio', 'verso-title', 'recto-title', 'recto-folio']
      .map((id) => ({ id, ...ARABIC_LABEL, fontSize: pt(9) })) },
    calloutStyles: [{ id: 'note', titleStyle: { ...ARABIC_LABEL, fontSize: pt(10) },
      body: { fontSize: pt(11.5), lineHeight: pt(19) } }],
    tableStyle: { headerFontFamily: 'IBM Plex Sans Arabic', headerFontSize: pt(9),
      bodyFontFamily: 'IBM Plex Sans Arabic', bodyFontSize: pt(9.4) },
    captionStyle: { fontFamily: 'IBM Plex Sans Arabic', fontSize: pt(9) },
    paragraphStyles: [{ id: 'colophon', fontFamily: 'IBM Plex Sans Arabic', fontSize: pt(8.4),
      lineHeight: pt(13) }],
  },
};
const edition = mergeConfigLayers(config, overrides[LANG]); // config itself for en and es
// #endregion

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
title: "Three Astrolabes"
subtitle: "Instruments of the sky in brass"
author: "Cabinet of Instruments"
---

# Three\\Astrolabes {style="cover" kicker="Cabinet of Instruments · No. 3" facts="Yemen 1291 · Iran 1654 · Europe 1462"}

## A map of the sky you can turn

An astrolabe is the night sky pressed flat. Its maker projects the celestial sphere onto the plane of the equator, so that every circle of the sky stays a circle on the brass, and a reader can turn the stars by hand to match the hour. With it an astronomer could find the time by day or by night, the height of a tower, the direction of Mecca or the moment a star would rise.

The instrument is a stack of parts held on one pin. The body, the *mater*, has a raised rim engraved with the hours or the degrees. Inside it lie the plates, one for each latitude where the instrument would be used, engraved with the circles of altitude and the lines of direction for that place. Over them turns the rete, a pierced frame whose pointers mark the bright stars and whose ring carries the Sun’s path through the year. On the back an alidade, a sighting rule, measures how high a star stands.

The words came to Europe with the instrument. Arabic astronomers called the rete *al-ʿankabūt*, the spider, and Latin writers kept the name as *aranea*; the alidade is *al-ʿiḍāda*, the rule, in a Latin spelling.

The three instruments in this booklet were made almost four centuries and thousands of kilometres apart. They share the same parts and the same geometry, and each one carries the language and the taste of the workshop that made it.

## The sultan’s instrument

The oldest of the three was made in Yemen in 1291 by ʿUmar ibn Yūsuf, a prince of the Rasulid house who ruled the country as sultan from 1295 to 1296. He was also an author on astronomy and wrote on how astrolabes should be built, and his own instrument shows that he knew the craft: the brass is cast and hammered, pierced and chased, and inlaid with silver. Four plates, each 12.7 cm across, fit inside a case 15.6 cm wide.

:::callout{type="note" title="Telling the time by a star"}
Hold the astrolabe by its ring and sight a bright star through the alidade; read its altitude on the scale of the back. On the front, turn the rete until that star’s pointer lies on the circle of the same altitude. A rule laid from the centre across the Sun’s place on the ring then points to the hour on the rim.
:::

## A garden of stars

::resource{id="mashhad"}

The second instrument comes from Safavid Iran. Muhammad Zaman, who was active from 1643 to 1689 and whose name al-Asturlabi means the astrolabe maker, finished it in 1654–55, probably in Mashhad. Its rete is a lattice of leaves and scrolls, so that the star pointers seem to grow from a climbing plant. The throne, the piece that carries the ring, rises above the rim in a pointed arch. An instrument like this served its owner every day, for the hours of prayer and the direction of Mecca, and it also showed a patron’s taste on the shelf of a library.

## Three instruments side by side

The third was made in Europe in 1462 and is attributed to the astronomer Regiomontanus, Johannes Müller (1436–1476). It is the smallest of the three, 13.5 cm high and 283 grams in weight, and the plainest, and its star names are in Latin, many of them Arabic names in a Latin spelling.

::resource{id="regiomontanus"}

Regiomontanus worked in Vienna, in Italy and in Nuremberg, and wrote on the tables and instruments of astronomy. An astrolabe of his time was read exactly as its Arabic models were, with the same rete, the same plates and the same alidade on the back.

Set side by side, the three instruments answer the same questions with the same moving parts. What changes is the script on the brass and the ornament around the stars. A reader who has learned one of them can read the other two.

::resource{id="three"}

:::paragraphs{style="colophon"}
Cabinet of Instruments, booklet 3. Also published in Spanish and in Arabic, from the same design · Set in Source Serif 4 and Source Sans 3 (SIL OFL) · Text: original, CC BY 4.0 · Photographs: The Metropolitan Museum of Art, New York, Open Access (CC0).
:::
`; // content.<lang>.md, inlined by the Cookbook

// #region pictures: three photographs, the figures wrapped at the end side of the text
const photo = (id, file, w, h, extra = {}) => ({ id, typeId: 'figure', kind: 'bitmap',
  createdAt: 0, updatedAt: 0, ...extra,
  bitmap: { fileId: file, format: 'jpeg', width: w, height: h } });
// 'end' is the right of an English column and the left of an Arabic one.
const wrapped = { position: 'here', wrap: 'end', width: 0.38 };
const note = (n) => `The Met, ${n}, CC0`;
const resources = [
  photo('rasulid', 'rasulid-cover-1400.jpg', 1400, 1985),
  photo('mashhad', 'mashhad-800.jpg', 800, 1187, { placement: wrapped, note: note('63.166a–j'),
    caption: t({ en: 'Planispheric astrolabe, Iran, 1654–55. Brass and steel.',
      es: 'Astrolabio planisférico, Irán, 1654-1655. Latón y acero.',
      ar: 'أسطرلاب مسطّح، إيران، ١٠٦٥\u00a0هـ / ١٦٥٤–١٦٥٥\u00a0م. نحاس أصفر وفولاذ.' }),
    altText: t({ en: 'A brass astrolabe whose rete is a lattice of leaves and scrolls',
      es: 'Un astrolabio de latón cuya red es un enrejado de hojas y volutas',
      ar: 'أسطرلاب من النحاس الأصفر عنكبوته شبكة من الأوراق والأغصان الملتفّة' }) }),
  photo('regiomontanus', 'regiomontanus-800.jpg', 800, 1083,
    { placement: wrapped,
    note: note('2025.347a–j'),
    caption: t({ en: 'Astrolabe attributed to Regiomontanus, 1462. Copper alloy.',
      es: 'Astrolabio atribuido a Regiomontano, 1462. Aleación de cobre.',
      ar: 'أسطرلاب يُنسب إلى ريجيومونتانوس، ١٤٦٢\u00a0م. سبيكة نحاسية.' }),
    altText: t({ en: 'A round brass astrolabe with Latin star names on its rete',
      es: 'Un astrolabio redondo de latón con nombres latinos de estrellas en la red',
      ar: 'أسطرلاب مستدير من النحاس عليه أسماء نجوم لاتينية' }) }),
];
// #endregion

// #region table: the three instruments, in the edition's words and digits
const row = (...cells) => cells.map((content) => ({ content }));
const head2 = (...cells) => cells.map((content) => ({ content, isHeader: true }));
resources.push({ id: 'three', typeId: 'table', kind: 'table', createdAt: 0, updatedAt: 0,
  placement: { position: 'here' },
  caption: t({ en: 'The three instruments.', es: 'Los tres instrumentos.',
    ar: 'الأدوات الثلاث.' }),
  table: { model: { headerRowCount: 1, columnWidths: [1.15, 1.1, 1.2, 1.1], rows: t({
    en: [head2('Made', 'Where', 'Maker', 'Size'),
      row('1291', 'Yemen', 'ʿUmar ibn Yūsuf', '15.6 cm wide'),
      row('1654–55', 'Iran, Mashhad?', 'Muhammad Zaman', '21.6 cm high'),
      row('1462', 'Germany or Italy', 'Regiomontanus', '13.5 cm high')],
    es: [head2('Fecha', 'Lugar', 'Autor', 'Tamaño'),
      row('1291', 'Yemen', 'ʿUmar ibn Yūsuf', '15,6 cm de ancho'),
      row('1654-1655', 'Irán, ¿Mashhad?', 'Muhammad Zaman', '21,6 cm de alto'),
      row('1462', 'Alemania o Italia', 'Regiomontano', '13,5 cm de alto')],
    ar: [head2('التاريخ', 'المكان', 'الصانع', 'المقاس'),
      row('٦٩٠\u00a0هـ / ١٢٩١\u00a0م', 'اليمن', 'عمر بن يوسف', 'عرضه ١٥٫٦\u00a0سم'),
      row('١٠٦٥\u00a0هـ / ١٦٥٤\u00a0م', 'إيران، مشهد؟', 'محمد زمان', 'ارتفاعه ٢١٫٦\u00a0سم'),
      row('١٤٦٢\u00a0م', 'ألمانيا أو إيطاليا', 'ريجيومونتانوس', 'ارتفاعه ١٣٫٥\u00a0سم')] }) } } });
// #endregion

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
// The faces of all three editions; the Arabic ones set only the Arabic edition.
const FONTS = {
  'Source Serif 4': ['400', '400i', '600'],
  'Source Sans 3': ['400', '600', '700'],
  Amiri: ['400', '700'],
  'IBM Plex Sans Arabic': ['400', '600', '700'],
};

// ─── 4 · Build & show ───────────────────────────────────────────────────────
await loadFonts(FONTS, markdown);
await loadArabicFonts(FONTS, markdown); // gotcha: arabic-fonts-subset
await loadImage('rasulid-cover-1400.jpg', asset('rasulid-cover-1400.jpg'));
await loadImage('mashhad-800.jpg', asset('mashhad-800.jpg'));
await loadImage('regiomontanus-800.jpg', asset('regiomontanus-800.jpg'));
const doc = await withLoadedFonts(() => buildDocument({ markdown, resources }, edition),
  { ...kitFonts(FONTS), text: markdown });
showBook(doc, { title: t({ en: 'Three Astrolabes, English edition',
  es: 'Tres astrolabios, edición en español', ar: 'ثلاثة أسطرلابات، الطبعة العربية' }) });
offerPdf(() => renderToPdf(doc, { fontProvider: arabicPdfProvider, resourceBytes: imageBytes }),
  `${RECIPE}.pdf`);

// ─── Kit ── helpers shared by every Cookbook recipe · postext.dev/cookbook ─────

// ─── Kit · core v1 ── the same in every recipe · postext.dev/cookbook
function mm(value) { return { value, unit: 'mm' }; }
function pt(value) { return { value, unit: 'pt' }; }
function em(value) { return { value, unit: 'em' }; }
/** The sample language's string: t({ en: 'Figure', es: 'Figura' }). */
function t(strings) { return strings[LANG] ?? Object.values(strings)[0]; }
/** A file in this recipe's assets folder, served from the Postext repo by jsDelivr. */
function asset(file) { return `https://cdn.jsdelivr.net/gh/drnachio/postext@main/cookbook/${RECIPE}/assets/${file}`; }

// ─── Kit · fonts v3 ── the same in every recipe · postext.dev/cookbook
// Postext loads the faces a config asks for before layout and asks the kit
// for Fontsource's files, the ones the PDF embeds too.

/** buildDocumentWithFonts' options: the resolver, and FONTS' faces loaded
 *  with the config's. FONTS = { 'Family Name': ['400', '400i', '700'] }. */
function kitFonts(FONTS = {}) {
  const faces = Object.entries(FONTS).flatMap(([family, specs]) => specs.map((spec) =>
    ({ family, weight: parseInt(spec, 10), style: spec.endsWith('i') ? 'italic' : 'normal' })));
  return { resolve: fontsourceResolver, faces };
}

/** A face's files with their ranges: latin, then latin-ext and greek when
 *  `text` needs them (kitSubsetsFor). Null for a face Fontsource lacks. */
async function fontsourceResolver(family, weight, style, { text = '' } = {}) {
  const id = fontsourceId(family);
  const meta = await fontsourceMeta(family);
  if (meta && !(await fontsourceWeights(family, style)).includes(weight)) return null;
  kitStatus('Loading fonts…');
  const at = await fontsourceAt(id);
  return ['latin', ...kitSubsetsFor(text, meta)].map((subset) => ({
    source: `${at}files/${id}-${subset}-${weight}-${style}.woff2`,
    unicodeRange: kitRanges()[subset],
  }));
}

/** Each file's unicode-range (a function: the kit runs after the pen's code). */
function kitRanges() {
  return {
    latin: 'U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,'
      + 'U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD',
    'latin-ext': 'U+0100-02BA,U+02BD-02C5,U+02C7-02CC,U+02CE-02D7,U+02DD-02FF,U+0304,U+0308,U+0329,'
      + 'U+1D00-1DBF,U+1E00-1E9F,U+1EF2-1EFF,U+2020,U+20A0-20AB,U+20AD-20C0,U+2113,U+2C60-2C7F,U+A720-A7FF',
    greek: 'U+0370-03FF',
  };
}

/** For the cjk, arabic and comics blocks: loads `faces` (as FONTS) for the
 *  sample `text`; `optional` skips a face Fontsource lacks. Files are added in
 *  the order asked, the last winning a shared character. Resolves to the count. */
async function loadFonts(faces, text = '', { optional = false } = {}) {
  kitStatus('Loading fonts…');
  const ranges = kitRanges();
  const jobs = [];
  for (const [family, specs] of Object.entries(faces)) {
    const id = fontsourceId(family);
    const todo = [...new Set(specs)].map((spec) => [parseInt(spec, 10), spec.endsWith('i') ? 'italic' : 'normal'])
      .filter(([weight, style]) => !hasFace(family, weight, style)); // before any await
    const at = fontsourceAt(id);
    const meta = optional || /[^\0-ÿ]/u.test(text) ? await fontsourceMeta(family) : null;
    const subsets = ['latin', ...kitSubsetsFor(text, meta)];
    for (const [weight, style] of todo) {
      if (optional && !(meta && (await fontsourceWeights(family, style)).includes(weight))) continue;
      for (const subset of subsets) {
        const url = `${await at}files/${id}-${subset}-${weight}-${style}.woff2`;
        const face = new FontFace(family, `url(${url}) format('woff2')`,
          { weight: String(weight), style, unicodeRange: ranges[subset] });
        jobs.push(face.load().catch(() => {
          if (subset === 'latin' && !optional) throw new Error(`Fontsource has no ${family} ${weight} ${style}`);
        }));
      }
    }
  }
  const ready = await Promise.all(jobs).catch((error) => { kitFail(error); throw error; });
  return ready.filter((face) => face && document.fonts.add(face)).length;
}

/** A loaded FontFace covers this face (fonts.check() says yes to any family). */
function hasFace(family, weight, style) {
  for (const face of document.fonts) {
    if (face.status !== 'loaded' || face.style !== style) continue;
    if (face.family.replace(/^["']|["']$/g, '') !== family) continue;
    const [low, high = low] = face.weight.split(' ').map(Number);
    if (weight >= low && weight <= high) return true;
  }
  return false;
}

/** The files beyond latin `text` needs that `meta`'s family ships. */
function kitSubsetsFor(text, meta) {
  return [[/[Ā-˿ᴀ-ᶿḀ-ỿ†ℓⱠ-Ɀ꜠-ꟿ]/u, 'latin-ext'], [/[Ͱ-Ͽ]/u, 'greek']]
    .filter(([re, x]) => re.test(text) && meta?.subsets?.includes(x)).map(([, x]) => x);
}

/** Fontsource's id for a family: 'Source Serif 4' → 'source-serif-4'. */
function fontsourceId(family) { return family.toLowerCase().replace(/\s+/g, '-'); }

/** A package's folder at the one version @5 names now (#766). */
function fontsourceAt(id, u = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@`) {
  return (fontsourceAt.c ??= {})[id] ??= fetch(u + '5/package.json').then((r) => r.json())
    .then((p) => p.version || 5, () => 5).then((v) => `${u}${v}/`);
}

/** The family's Fontsource metadata (weights, styles, subsets), or null. */
function fontsourceMeta(family, id = fontsourceId(family)) {
  return (fontsourceMeta.c ??= {})[id] ??= fetch(`https://api.fontsource.org/v1/fonts/${id}`)
    .then((res) => (res.ok ? res.json() : null), () => null);
}

/** The weights the package ships in `style`: the API pairs none (no Libre
 *  Caslon 700 italic file), so italics are read from latin-italic.css. */
function fontsourceWeights(family, style, id = fontsourceId(family)) {
  return (fontsourceWeights.c ??= {})[id + style] ??= fontsourceMeta(family).then(async (m) => {
    if (!m?.styles.includes(style)) return m ? [] : [400, 700];
    const css = style === 'italic' ? await fetch(`${await fontsourceAt(id)}latin-italic.css`).then((r) => (r.ok ? r.text() : ''), () => '') : '';
    const w = [...css.matchAll(/weight: (\d+)/g)].map((x) => +x[1]);
    return w.length ? w : m.weights;
  });
}

// ─── Kit · viewer v2 ── the same in every recipe · postext.dev/cookbook
/** The pages as spreads on a dark desk, page 1 alone, then verso | recto,
 *  each painted when it scrolls near. Other options go to renderPageToCanvas. */
function showPages(docs, { title, width = 460, ...render } = {}) {
  const root = viewer(title);
  const pages = [docs].flat().flatMap((doc) =>
    doc.pages.map((page) => ({ doc, page, n: (doc.pageIndexOffset ?? 0) + page.index })));
  const spreads = [];
  let verso = null;
  for (const p of pages) {
    if (p.n % 2 === 1) { if (verso) spreads.push([verso, null]); verso = p; }
    else { spreads.push([verso, p]); verso = null; }
  }
  if (verso) spreads.push([verso, null]);
  const density = Math.min(window.devicePixelRatio || 1, 2);
  showPages.painter?.disconnect();
  const painter = new IntersectionObserver((entries) => {
    for (const { isIntersecting, target } of entries) {
      if (!isIntersecting) continue;
      painter.unobserve(target);
      const { doc, page } = target.postext;
      renderPageToCanvas(page, doc, target, { ...render, scale: (width * density) / page.width });
    }
  }, { rootMargin: '800px' });
  showPages.painter = painter;
  root.replaceChildren(...spreads.map((pair) => {
    const spread = document.createElement('div');
    spread.className = 'pt-spread';
    for (const p of pair) {
      const figure = document.createElement('figure');
      if (p) {
        const label = p.page.pageLabel || String(p.n + 1);
        const canvas = document.createElement('canvas');
        canvas.postext = p;
        canvas.style.aspectRatio = `${p.page.width} / ${p.page.height}`;
        canvas.setAttribute('role', 'img');
        canvas.setAttribute('aria-label', `Page ${label}`);
        const folio = document.createElement('figcaption');
        folio.textContent = label;
        figure.append(canvas, folio);
        painter.observe(canvas);
      } else figure.className = 'pt-blank';
      spread.append(figure);
    }
    return spread;
  }));
  kitStatus(`${pages.length} ${pages.length === 1 ? 'page' : 'pages'}`);
  document.documentElement.dataset.postext = 'ready';
  return pages.length;
}

/** The desk, the bar and the error reporting, created once. */
function viewer(title) {
  if (!document.getElementById('pt-kit')) {
    document.head.insertAdjacentHTML('beforeend', `<style id="pt-kit">
      :root { color-scheme: dark; }
      body { margin: 0; background: #0e1014; color: #b9bcc4; font: 13px/1.45 system-ui, sans-serif; }
      #pt-bar { position: sticky; top: 0; z-index: 1; display: flex; flex-wrap: wrap; align-items: center;
        gap: 6px 16px; padding: 10px 16px; background: rgb(14 16 20 / .92); backdrop-filter: blur(6px);
        border-bottom: 1px solid #23262d; }
      #pt-bar strong { color: #f4f1ea; font-weight: 600; }
      #pt-actions { display: flex; gap: 12px; margin-left: auto; }
      #pt-actions a, #pt-actions button { color: #d8a21a; font: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
      #pages { display: grid; justify-items: center; gap: 48px; padding: 32px 16px 72px; }
      .pt-spread { display: flex; }
      .pt-spread figure { margin: 0; width: min(460px, 44vw); }
      .pt-spread canvas { display: block; width: 100%; background: #fff;
        box-shadow: 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figure:first-child canvas { box-shadow: inset -14px 0 14px -14px rgb(0 0 0 / .18), 0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
      .pt-spread figcaption { margin-top: 10px; text-align: center; font: 600 10px/1 system-ui, sans-serif;
        letter-spacing: .18em; text-transform: uppercase; color: #6c7079; }
      .pt-blank { visibility: hidden; }
      @media (max-width: 760px) {
        .pt-spread { flex-direction: column; gap: 32px; }
        .pt-spread figure { width: min(460px, 92vw); }
        .pt-blank { display: none; }
      }
    </style>`);
    document.body.insertAdjacentHTML('afterbegin',
      '<header id="pt-bar"><strong id="pt-title"></strong><span id="pt-status" role="status"></span><span id="pt-actions"></span></header>');
    document.getElementById('pt-title').textContent = document.title || 'Postext';
    addEventListener('error', (event) => kitFail(event.error ?? event.message));
    addEventListener('unhandledrejection', (event) => kitFail(event.reason));
  }
  if (title) document.getElementById('pt-title').textContent = title;
  return document.getElementById('pages')
    ?? document.body.appendChild(Object.assign(document.createElement('main'), { id: 'pages' }));
}

function kitStatus(text) {
  viewer();
  document.getElementById('pt-status').textContent = text;
}

function kitFail(error) {
  document.documentElement.dataset.postext = 'error';
  kitStatus(`Error: ${error?.message ?? error}`);
}

// ─── Kit · pdf v3 ── the same in every recipe that exports a PDF
/** The Fontsource files the screen used, as TrueType, with their range and
 *  place: the nearest weight the family ships in that style, upright with no italic;
 *  latin, then what its letters need (kitSubsetsFor). */
async function fontsourceProvider(family, weight, style, request) {
  const id = fontsourceId(family);
  const meta = await fontsourceMeta(family);
  const s = style === 'italic' && meta && !meta.styles.includes('italic') ? 'normal' : style;
  const shipped = meta ? await fontsourceWeights(family, s) : [];
  const weights = shipped.length ? shipped : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const text = String.fromCodePoint(...(request?.codePoints ?? []));
  const files = await Promise.all(['latin', ...kitSubsetsFor(text, meta)].map(async (subset, order) => {
    const res = await fetch(`${await fontsourceAt(id)}files/${id}-${subset}-${w}-${s}.woff2`);
    if (!res.ok) throw new Error(`Fontsource has no ${family} ${w} ${s} ${subset}`);
    return Object.assign(await decompressWoff2(new Uint8Array(await res.arrayBuffer())),
      { unicodeRange: kitRanges()[subset], order });
  }));
  return files.length === 1 ? files[0] : files;
}

/** A "Build the PDF" button; then "Open the PDF" (a new tab: CodePen's frame
 *  shows no PDFs) and a download link. */
function offerPdf(makePdf, filename) {
  viewer();
  const button = Object.assign(document.createElement('button'), { type: 'button', textContent: 'Build the PDF' });
  button.dataset.postextPdf = filename;
  button.addEventListener('click', async () => {
    button.disabled = true;
    button.textContent = 'Building the PDF…';
    try {
      const bytes = await makePdf();
      const url = URL.createObjectURL(new Blob([bytes], { type: 'application/pdf' }));
      const size = `${Math.max(1, Math.round(bytes.length / 1024))} KB`;
      button.replaceWith(
        Object.assign(document.createElement('a'), { href: url, target: '_blank', rel: 'noopener', textContent: 'Open the PDF ↗' }),
        Object.assign(document.createElement('a'), { href: url, download: filename, textContent: `Download ${filename} · ${size}` }));
    } catch (error) {
      button.disabled = false;
      button.textContent = 'Build the PDF';
      kitFail(error);
    }
  });
  document.getElementById('pt-actions').append(button);
}

// ─── Kit · images v3 ── recipes with pictures · postext.dev/cookbook
/** Registers a photo or PNG for the canvas and keeps its bytes for the PDF.
 *  fetch → ImageBitmap never taints the canvas (a plain cross-origin <img> would). */
async function loadImage(fileId, url) {
  const res = await fetch(url);
  if (!res.ok) throw new Error(`Image not found (${res.status}): ${url}`);
  const bytes = new Uint8Array(await res.arrayBuffer());
  registerResourceImage(fileId, await createImageBitmap(new Blob([bytes])));
  (loadImage.bytes ??= new Map()).set(fileId, bytes);
}

/** Registers SVG markup as a vector image, its fonts inside (inlineSvgFonts, ≥ 1.25).
 *  `options` go to registerResourceImage: { singleInk: true } tints it on the canvas. */
async function loadSvg(fileId, svg, options) {
  if (typeof inlineSvgFonts === 'function') svg = await inlineSvgFonts(svg, svgFaces);
  const img = new Image();
  img.src = `data:image/svg+xml;charset=utf-8,${encodeURIComponent(svg)}`;
  await img.decode();
  registerResourceImage(fileId, img, options);
  (loadImage.bytes ??= new Map()).set(fileId, new TextEncoder().encode(svg));
}

/** A face's Fontsource files: nearest weight; latin + what the SVG sets. */
async function svgFaces(family, weight, style, { codePoints = [] } = {}) {
  const [id, m] = [fontsourceId(family), await fontsourceMeta(family)];
  const w = m?.weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a)) ?? weight;
  const s = m?.styles.includes(style) === false ? 'normal' : style;
  return Promise.all(['latin', ...kitSubsetsFor(String.fromCodePoint(...codePoints), m)].map(async (x) => new Uint8Array(
    await (await fetch(`${await fontsourceAt(id)}files/${id}-${x}-${w}-${s}.woff2`)).arrayBuffer())));
}

/** renderToPdf({ resourceBytes: imageBytes }) */
function imageBytes(fileId) { return loadImage.bytes?.get(fileId); }

/** renderToHtml({ resourceImageUrl: imageUrl }) */
function imageUrl(fileId) {
  const bytes = imageBytes(fileId);
  if (!bytes) return undefined;
  imageUrl.urls ??= new Map();
  if (!imageUrl.urls.has(fileId)) {
    const type = /\.svg$/i.test(fileId) ? 'image/svg+xml' : /\.png$/i.test(fileId) ? 'image/png' : 'image/jpeg';
    imageUrl.urls.set(fileId, URL.createObjectURL(new Blob([bytes], { type })));
  }
  return imageUrl.urls.get(fileId);
}

// ─── Kit · arabic v2 ── Arabic-script faces · postext.dev/cookbook
// Fontsource ships an Arabic family as one file per subset and weight: the
// `arabic` file holds the letters, the harakat, the Arabic-Indic digits, the
// Arabic punctuation and the presentation forms; `latin` and `latin-ext`
// hold the rest. loadFonts loads the latin files; this block adds the arabic
// file of every Arabic family, for the canvas and for the PDF, which shapes
// the letters with HarfBuzz from the same bytes.

/** The code points of Fontsource's `arabic` subset, as its stylesheets
 *  declare them (the same unicode-range the browser picks the file by). A
 *  function, not a const: the kit is inlined after the recipe's top-level
 *  awaits, and a const read before its line throws, where a function
 *  declaration is hoisted. */
function arabicRange() {
  return 'U+0600-06FF,U+0750-077F,U+0870-088E,U+0890-0891,U+0897-08E1,U+08E3-08FF,'
    + 'U+200C-200E,U+2010-2011,U+204F,U+2E41,U+FB50-FDFF,U+FE70-FE74,U+FE76-FEFC,U+102E0-102FB,'
    + 'U+10E60-10E7E,U+10EC2-10EC4,U+10EFC-10EFF,U+1EE00-1EEFF';
}

/** Whether code point `cp` is in the arabic file. */
function inArabicRange(cp) {
  inArabicRange.ranges ??= arabicRange().split(',').map((part) => {
    const [lo, hi = lo] = part.slice(2).split('-');
    return [parseInt(lo, 16), parseInt(hi, 16)];
  });
  return inArabicRange.ranges.some(([lo, hi]) => cp >= lo && cp <= hi);
}

/** Whether Fontsource serves `family` with an `arabic` subset. Fails when
 *  the API does not answer: an Arabic face taken for a Latin one would set
 *  its letters in a system face. */
async function isArabicFamily(family) {
  const meta = await fontsourceMeta(family);
  if (!meta) throw new Error(`api.fontsource.org did not describe ${family}: reload to try again`);
  return !!meta.subsets?.includes('arabic');
}

/** The arabic file of a face. */
async function arabicFileUrl(family, weight, style) {
  const id = fontsourceId(family);
  return `${await fontsourceAt(id)}files/${id}-arabic-${weight}-${style}.woff2`;
}

/** faces = { Amiri: ['400', '700'] }, as for loadFonts, after it: the whole
 *  FONTS object may be passed, its families without an arabic subset are
 *  left alone. Adds the arabic file of every listed weight of each Arabic
 *  family (the latin files come from loadFonts) and loads it. `text` is
 *  the sample: fails when it holds an Arabic-script character the arabic
 *  file does not cover. List every weight the pages set in Arabic: a weight
 *  left to the engine's later round gets the latin file only, and its Arabic letters
 *  fall back to a system face. Resolves to the number of files loaded. */
async function loadArabicFonts(faces, text = '') {
  kitStatus('Loading fonts…');
  let loaded = 0;
  try {
    const outside = [...new Set(text)].filter((ch) => /\p{Script=Arabic}/u.test(ch) && !inArabicRange(ch.codePointAt(0)));
    if (outside.length) throw new Error(`Fontsource's arabic files have no ${outside.slice(0, 12).join(' ')}`);
    for (const [family, specs] of Object.entries(faces)) {
      if (!(await isArabicFamily(family))) continue;
      for (const spec of new Set(specs)) {
        const weight = parseInt(spec, 10);
        const style = spec.endsWith('i') ? 'italic' : 'normal';
        const face = new FontFace(family, `url(${await arabicFileUrl(family, weight, style)}) format('woff2')`,
          { weight: String(weight), style, unicodeRange: arabicRange() });
        document.fonts.add(await face.load().catch(() => {
          throw new Error(`Fontsource has no arabic file for ${family} ${weight} ${style}`);
        }));
        loaded++;
      }
    }
  } catch (error) {
    kitFail(error);
    throw error;
  }
  return loaded;
}

/** The PDF font provider for recipes with Arabic faces: a family with an
 *  arabic subset gets its arabic file when its pages set Arabic letters
 *  (`request.codePoints`), then its latin file, and its latin-ext file for
 *  the letters beyond latin (transliteration: ā ḥ ʿ), each marked with its
 *  unicode-range and its place in the order the screen added them (latin
 *  and latin-ext by loadFonts, then arabic): the arabic file also has a
 *  space and brackets, which the browser takes from latin, the file whose
 *  range holds them, and postext-pdf follows it. Any other family goes to
 *  fontsourceProvider (the "pdf" block). */
async function arabicPdfProvider(family, weight, style, request) {
  if (!(await isArabicFamily(family))) return fontsourceProvider(family, weight, style, request);
  const meta = await fontsourceMeta(family);
  const weights = meta.weights?.length ? meta.weights : [400, 700];
  const w = weights.reduce((a, b) => (Math.abs(b - weight) < Math.abs(a - weight) ? b : a));
  const s = style === 'italic' && !meta.styles.includes('italic') ? 'normal' : style;
  const wanted = [...(request?.codePoints ?? [])];
  const id = fontsourceId(family);
  const subsets = !wanted.length || wanted.some(inArabicRange) ? ['arabic', 'latin'] : ['latin'];
  if (meta.subsets.includes('latin-ext') && wanted.some((cp) => /[Ā-˿Ḁ-ỿ]/u.test(String.fromCodePoint(cp)))) {
    subsets.push('latin-ext');
  }
  const at = await fontsourceAt(id);
  return Promise.all(subsets.map(async (subset) => {
    const url = `${at}files/${id}-${subset}-${w}-${s}.woff2`;
    const res = await fetch(url);
    if (!res.ok) throw new Error(`Fontsource file ${url} (${res.status})`);
    const bytes = await decompressWoff2(new Uint8Array(await res.arrayBuffer()));
    return Object.assign(bytes, { unicodeRange: subset === 'arabic' ? arabicRange() : kitRanges()[subset],
      order: ['latin', 'latin-ext', 'greek', 'arabic'].indexOf(subset) });
  }));
}

// ─── Kit · book v1 ── books bound on either edge · postext.dev/cookbook
// A book bound on the right (Arabic, Hebrew or Persian text, vertical
// Chinese, or page.binding 'right') opens from what a Latin reader calls
// the back: page 1 lies alone on the left of the spine, then [3 | 2].

/** showPages for a book bound on either edge. A right-bound book (the
 *  document says so: doc.binding is 'right' for page.binding 'right', for
 *  text that runs right to left and for vertical text, when the binding is
 *  left to 'auto') lies on the desk as it opens: page 1 alone on the left
 *  of the spine, then [3 | 2], the spine shade on each page's inner edge.
 *  `binding` ('left' | 'right') overrides the document's. */
function showBook(docs, { binding, ...options } = {}) {
  const count = showPages(docs, options);
  const right = (binding ?? [docs].flat()[0]?.binding) === 'right';
  if (!document.getElementById('pt-kit-book')) {
    // The pages keep direction ltr, as in a left-bound book: a canvas takes
    // the direction its element inherits, and under the spread's rtl a run
    // painted for an ltr canvas would end where the engine starts it.
    document.head.insertAdjacentHTML('beforeend', `<style id="pt-kit-book">
      .pt-spread[dir="rtl"] canvas { direction: ltr; }
      .pt-spread[dir="rtl"] figure:first-child canvas { box-shadow: inset 14px 0 14px -14px rgb(0 0 0 / .18),
        0 1px 2px rgb(0 0 0 / .5), 0 22px 44px -16px rgb(0 0 0 / .8); }
    </style>`);
  }
  // Each pair stays [verso, recto] in the page; right to left, the verso
  // sits on the right. Phones stack the pages in reading order either way.
  for (const spread of document.querySelectorAll('#pages > .pt-spread')) spread.dir = right ? 'rtl' : 'ltr';
  document.getElementById('pages').dataset.binding = right ? 'right' : 'left';
  return count;
}

// ─── /Kit ───────────────────────────────────────────────────────────────────────
```

## Variations

### Write the overrides into a bundle

[The .postext round trip](https://postext.dev/en/cookbook/bundle-round-trip.md) writes a book in two languages to one file. Since postext 1.58 `createBundle` stores the general settings once and each language's override beside its chapters, as `mergeConfigLayers` reads them here. The Sandbox book of this recipe opens that way: switch the Design panel between *All languages* and the Arabic edition to see which fields the Arabic edition sets.

### Print the Arabic edition for the Maghreb

`ar-MA` keeps the direction and the binding and writes the generated numbers, the folios and the figure numbers, in European digits. Retype the table's digits too.

```diff
-  locale: t({ en: 'en-gb', es: 'es', ar: 'ar' }), // ar: right to left, bound on the right
+  locale: t({ en: 'en-gb', es: 'es', ar: 'ar-MA' }), // ar-MA: European digits
```

## Pitfalls

- **Arabic faces need their arabic file, through the arabic block.** Fontsource serves Amiri, Noto Naskh Arabic or Scheherazade New as one file per subset, and the Arabic letters are in the arabic file. loadFonts fetches only latin (and latin-ext), so on screen the Arabic comes from a system face and measures wrong, and fontsourceProvider hands the PDF that latin file, which prints empty boxes. List the arabic kit block, call loadArabicFonts(FONTS, markdown) after loadFonts, with every weight the pages set in Arabic listed in FONTS, and give renderToPdf fontProvider: arabicPdfProvider.

- Arabic letters join, so a label tracked in the general settings must lose its `letterSpacing` in the Arabic override, or the engine raises a `joiningScriptLetterSpacing` warning. `textTransform: 'none'` goes with it: Arabic has no capitals.
- The lines of an Arabic edition are deeper, so its pages break in other places. Each edition here was fitted on its own: the Arabic box floats to the foot of its page (`placement="bottom"`) and its closing sentences run beside the last photograph.

## Credits

- Recipe: Ignacio Ferro ([@drnachio](https://github.com/drnachio))
- Images: Astrolabe of ʿUmar ibn Yusuf, Yemen, 1291 (the cover; background extended at the top and darkened): The Metropolitan Museum of Art ([source](https://www.metmuseum.org/art/collection/search/444408)), CC0-1.0
- Images: Muhammad Zaman, planispheric astrolabe, Iran, 1654–55 (cropped): The Metropolitan Museum of Art ([source](https://www.metmuseum.org/art/collection/search/451699)), CC0-1.0
- Images: Astrolabe attributed to Regiomontanus, 1462 (cropped): The Metropolitan Museum of Art ([source](https://www.metmuseum.org/art/collection/search/923639)), CC0-1.0
- Type: Source Serif 4 (OFL-1.1), Source Sans 3 (OFL-1.1), Amiri (OFL-1.1), IBM Plex Sans Arabic (OFL-1.1)
- Code: MIT · Sample content: CC-BY-4.0

## Related

- [Nº 041 · .postext round trip in two languages](https://postext.dev/en/cookbook/bundle-round-trip.md): A two-sided DL leaflet written to a .postext file in code and laid out again from its bytes, with the faces, drawings and caption labels each edition carries. · Level 2 (Intermediate) · Single sheets & ephemera
- [Nº 173 · An Arabic workbook, right to left](https://postext.dev/en/cookbook/arabic-workbook-rtl.md): A primary Arabic workbook unit set right to left: choices with أ ب ج, matching columns, a word bank, صح or خطأ boxes, a word search and Arabic-Indic digits. · Level 2 (Intermediate) · Workbooks & exercises, Textbooks
- [Nº 153 · One page lettered in six languages](https://postext.dev/en/cookbook/one-page-six-languages.md): One comic page, split and pictures fixed, lettered per language: the locale picks the face; Japanese runs vertical and, like Arabic, reads from the right. · Level 3 (Advanced) · Comics