成品一览

Seedlings Science的练习单3A，这是一套虚构的面向八岁儿童的系列教材，共四页，200 × 260 mm，单面印刷。叶绿色色带上有黄色的单元标签、标题，以及填写姓名和日期的白色栏位；旁边一个白色圆盘里是一株豌豆，六个部位用黄色编号标出。每个活动都是一个带编号的标题，下面是一张浅绿色卡片。卡片里有：带灰色小提示、可写好几行的白色答题框，由黄色行内标签组成的词库，句子中描边的空，一张把食物和植物部位对应起来的表格，以及一份用来涂色的圆圈检查清单。每个答题框位于题目下方2 mm，距后面的内容5 mm；每张卡片结束处距本页后面的任何内容都是9 mm。正文字体是Andika，这是SIL为学习阅读的儿童设计的字体。

这道食谱解答

怎样嵌套框，比如装着答题框的练习卡片，并精确控制间距？
怎样做练习页：填空横线、答题框、词库、清单？
怎样做行内标签：键盘按键、标签、练习用的词库？
怎样在表格单元格里放图片或图标？

简短回答

script.js · 第24–56行在完整代码中

// In the Markdown a box inside a box is a fence inside a fence (each ::: closes one):
//   :::callout{type="card"}
//   What is inside the pea pods?
//   :::callout{type="answer"}
//   Write here               ← a prompt first: a box of :::space alone collapses
//   :::space{lines=3}           (gotcha: space-dropped-box-top)
//   :::
//   :::
const [ASK, AFTER, HEAD, NEXT] = [2, 5, 3, 9]; // mm: question→box, box→next, heading→card
const card = {
  id: 'card', background: col('tint'), borderRadius: mm(4),
  padding: { top: mm(4), right: mm(5), bottom: mm(5), left: mm(5) },
  marginTop: mm(HEAD), marginBottom: mm(NEXT), // NEXT: under a card, to whatever follows
  // Off the grid, or what follows a card drops to the next grid line. Only the outer card can
  // set it: a nested box ignores snapToGrid, span and placement (gotcha: nested-callout-limits).
  snapToGrid: false,
  body: { paragraphSpacing: false }, // the boxes' margins do all the spacing
  lists: { bulletChar: '', // no bullet: in the checklist a circle chip opens each item
    gap: mm(2), itemSpacing: pt(7) }, columnGap: mm(6),
};
// A nested box's margins collapse with its neighbours', the larger winning (ASK, AFTER); the
// last box's marginBottom falls inside the card's padding instead of adding to it.
const nested = (id, look) => ({ id, background: col('paper'), borderRadius: mm(2.5),
  marginTop: mm(ASK), marginBottom: mm(AFTER), ...look });
const answer = nested('answer', { border: { enabled: true, color: col('rule'), width: pt(0.75) },
  padding: { top: mm(1.6), right: mm(3), bottom: mm(2), left: mm(3) },
  // A small grey prompt on a full 17 pt line; :::space counts in these body lines.
  body: { fontFamily: LABEL, fontSize: pt(8), color: col('muted') } });
const bank = nested('bank', { title: t({ en: 'Word bank', es: 'Banco de palabras' }),
  padding: { top: mm(2.2), right: mm(3), bottom: mm(2.4), left: mm(3) },
  titleStyle: { fontFamily: LABEL, fontSize: pt(7.5), fontWeight: 600, color: col('leaf'),
    textTransform: 'uppercase', letterSpacing: pt(1.3), gap: mm(1.6) } });
// config() plugs in all three: calloutStyles: [card, answer, bank].

做法

#1 · 标题也脱离网格

script.js · 第158–166行在完整代码中

  headings: { fontFamily: DISPLAY, snapToGrid: false, // or what follows snaps back to the grid
    balancing: { enabled: false }, // no extra space above headings to fill out a page
    levels: [
      // Restated: any headings object drops the H1 break (gotcha: headings-drop-h1-break).
      { level: 1, span: 'page', breakBefore: { enabled: true, parity: 'any' },
        marginTop: pt(0), marginBottom: pt(0), advancedDesign: opener() },
      { level: 2, numberingTemplate: '{2}', marginTop: mm(0), marginBottom: mm(0),
        advancedDesign: activity },
    ] },

在简短回答中，每个框的外边距与相邻框的外边距折叠，取较大的一个。词库的5 mm压过了下方列表上面的2 mm，最后一个答题框的5 mm落在卡片5 mm的底部内边距之内，而不是叠加上去。如果留在网格上，二级标题会占用10.8到14.1 mm，而不是其圆盘的8.6 mm，因为标题后面的内容会回到下一条17 pt的行上；headings.snapToGrid: false让它保持8.6 mm。在嵌套样式上设置snapToGrid没有作用，因为只有外层卡片可以脱离网格（嵌套框）。各栏齐底已关闭，因为它会在标题上方加空来填满页面；在第2页，它会在活动3上方留出33 mm而不是9 mm。

#2 · 每个空都用行内标签

script.js · 第60–74行在完整代码中

const chip = (id, fill, look) => ({ id, fontFamily: LABEL, background: col(fill),
  borderWidth: pt(0), borderColor: col('leaf'), borderRadius: em(1), ...look });
// An empty chip holds a U+2060 word joiner, as one of spaces prints its markup (gotcha:
// empty-chip). Its box is a band 1.25 em tall, so paddingX ROUND makes it a circle.
const [EMPTY, ROUND, OUTLINE] = ['\u2060', em(0.625), pt(0.9)];
// A blank is all padding, 2 × paddingX wide and 19.6 pt tall: taller than the 17 pt line, so
// the card's itemSpacing sets its items 24 pt apart (gotcha: chip-overlap).
const blank = (id, width) => chip(id, 'paper', { borderWidth: OUTLINE, borderRadius: mm(1.4),
  paddingX: mm(width / 2), paddingY: em(0.12), fontSize: em(1.15) });
const chipStyles = [
  chip('word', 'sun', { bold: true, paddingX: em(0.6), paddingY: em(0.08), gap: em(0.45) }),
  blank('blank', 34), blank('wide', 38), // mm: in a sentence; alone in a column
  chip('dot', 'leaf', { paddingX: ROUND, fontSize: em(0.6) }),
  chip('tick', 'paper', { borderWidth: OUTLINE, paddingX: ROUND, fontSize: em(1.1), gap: em(0.5) }),
];

行内标签是行内一个不可断开的框，它的内边距画在行外，不会让行变高。词库是嵌套的bank框中的一排行内标签。填空、待连线的点和待涂色的圆圈也都是行内标签，每个只包含一个U+2060词连接符，因为在postext 1.4.1中，由空格组成的行内标签会把标记原样印出来（行内标签）。宽度由paddingX设定：句中的空宽34 mm，单独占一栏时宽38 mm；圆圈两侧各留其1.25 em高度的一半。在检查清单中，圆圈占据项目符号的位置（bulletChar: ''）。空高19.6 pt，比17 pt的行高，所以每个空都独占一个列表项，与下一项相距24 pt。在1.4.1中，沙盒仍会对blank、wide和tick给出警告“行内标签碰到相邻行”，因为它拿每个标签与17 pt的行距比较，没有算上列表项之间的7 pt。

#3 · 用标题的版面设计给活动编号

script.js · 第78–92行在完整代码中

const DISC_H2 = 8.6; // mm: the disc and the title are this tall, so the heading reserves this
const numberDisc = { kind: 'text', id: 'num', content: '{number}', // numberingTemplate '{2}'
  fontFamily: DISPLAY, fontSize: pt(15), fontWeight: 800, color: col('paper'),
  box: { backgroundColor: col('leaf'), borderRadius: mm(DISC_H2 / 2) }, // centred both ways
  placement: { anchor: { to: 'container', edge: 'top-left' },
    size: { width: mm(DISC_H2), height: mm(DISC_H2) } } };
const activityTitle = { kind: 'text', id: 'title', content: '{titleText}',
  fontFamily: DISPLAY, fontSize: pt(17), fontWeight: 700, color: col('ink'), align: 'left',
  overflow: 'wrap', placement: { anchor: { to: '#num', edge: 'right-of' },
    offset: { x: mm(3) }, size: { width: mm(140), height: mm(DISC_H2) } } };
const activity = { enabled: true, slot: { elements: [numberDisc, activityTitle] } };
// ## How did I do? {style="review"} is not an activity: it has no number and a star for a disc.
const review = { id: 'review', numbered: false, advancedDesign: { ...activity, slot: {
  elements: [{ kind: 'image', id: 'num', resourceId: 'star', placement: numberDisc.placement },
    activityTitle] } } };

带advancedDesign的二级标题在栏中保留自己的位置，画出来的是版面设计而不是标题文字：一个圆盘装着{number}（印出该级的numberingTemplate），右边是{titleText}（通栏与高级版面设计）。圆盘和标题都是8.6 mm高，脱离网格后标题正好占这么多，所以版面设计不需要minHeight。编号来自二级标题的计数器，所以在Markdown中插入一个活动，后面的活动会自动重新编号。自我检查的标题使用numbered: false的样式，不参与计数，圆盘的位置放一颗SVG星星。

#4 · 把图片放进表格单元格

script.js · 第128–144行在完整代码中

const tableStyles = [{ id: 'match', borderRadius: mm(3), // no header row, so no header fill
  headerBackgroundEnabled: false, bodyBackgroundEnabled: true, bodyBackground: col('paper'),
  bodyFontFamily: LABEL, bodyFontSize: pt(13), bodyColor: col('ink'), cellPadding: mm(1.4),
  // White rules on the white panel: unseen, but they hide the canvas's seams between cells.
  rules: 'grid', borderColor: col('paper'), borderWidth: pt(1) }];
const cell = (content, extra) => ({ content, verticalAlign: 'middle', ...extra });
const dotCell = () => cell(`:chip[${EMPTY}]{style="dot"}`, { align: 'center' });
const matchRow = (icon, food, part) => [cell('', { image: { resourceId: icon, width: 0.76 },
  align: 'center' }), cell(food), dotCell(), cell(''), dotCell(),
cell(`:chip[${part}]{style="word"}`)];
const sheetType = { id: 'sheet', name: 'Worksheet item', shortLabel: '', captionPrefix: '',
  numberingTemplate: '{n}', resetOn: 'never', counterFormat: 'decimal' }; // no caption, no number
// Set 'here' in its card, after a :::space (gotcha: box-embed-no-gap); built once FOODS exist.
const foods = () => ({ id: 'foods', typeId: 'sheet', kind: 'table', createdAt: 0, updatedAt: 0,
  placement: { position: 'here' }, table: { styleId: 'match', model: {
    columnWidths: [0.14, 0.25, 0.06, 0.31, 0.06, 0.18], // the widest gap: room to draw a line
    rows: FOODS.map((name, r) => matchRow(ICONS[r], name, PARTS[r])) } } });

TableCell.image在单元格内画出一个资源，这里占单元格宽度的76 %，行高会随之增加。verticalAlign: 'middle'让食物名称、圆点和标签与图片垂直居中。最宽的一栏占表格的31 %，留空给学生画线。命名样式把表格的边框做成圆角，并把白色的表体填充裁到边框内。它的网格线也是白色的：Canvas会在有填充的单元格之间留下一条淡淡的细线，白色面板上一条1 pt的白线正好把它盖住（命名表格样式）。它的资源类型captionPrefix为空，表格也没有题注文字，所以下方不印题注。placement: { position: 'here' }把表格排在其::resource行所在的位置，也就是卡片里面。

完整食谱

沙盒

// ═══ Postext Cookbook · Nº 022 · Worksheet with answer boxes and a word bank ══════
// https://postext.dev/en/cookbook/worksheet-answer-boxes
// Code: MIT · Text: original (CC BY 4.0) · Drawings: generated in code (CC BY 4.0)
// Fonts: Andika, Baloo 2, Fredoka (SIL OFL 1.1) · Needs postext ≥ 1.4.1
import { buildDocument, renderPageToCanvas, clearMeasurementCache, registerResourceImage }
  from 'https://esm.sh/postext';

const LANG = 'en'; // @lang: the language of the sample document ('en' | 'es')
const RECIPE = 'worksheet-answer-boxes';

// ─── 1 · Design ─────────────────────────────────────────────────────────────
const palette = { ink: '#243040', muted: '#5d6975', paper: '#ffffff', // type; prompts; boxes
  leaf: '#2f7d4a', sun: '#f4b43a', soil: '#8a5a36', // the accent; words to pick; drawings
  tint: '#e5f1e7', rule: '#a9c9b1' }; // the activity cards; answer-box outlines
// Design elements read the hex and ignore the palette (gotcha: palette-skips-designs).
const col = (id) => ({ hex: palette[id], model: 'hex', paletteId: id });
// The engine's defaults link to 'main-color': point it at the leaf, so nothing prints blue.
const colorPalette = Object.entries({ ...palette, 'main-color': palette.leaf })
  .map(([id, hex]) => ({ id, name: id, value: { hex, model: 'hex' } }));
const [TEXT, DISPLAY, LABEL] = ['Andika', 'Baloo 2', 'Fredoka']; // Andika: for early readers
const [TOP, SIDE] = [18, 16]; // mm; a sheet printed one-sided, so the margins do not mirror

// #region answer: cards that hold white answer boxes, stacked exactly, off the grid
// In the Markdown a box inside a box is a fence inside a fence (each ::: closes one):
//   :::callout{type="card"}
//   What is inside the pea pods?
//   :::callout{type="answer"}
//   Write here               ← a prompt first: a box of :::space alone collapses
//   :::space{lines=3}           (gotcha: space-dropped-box-top)
//   :::
//   :::
const [ASK, AFTER, HEAD, NEXT] = [2, 5, 3, 9]; // mm: question→box, box→next, heading→card
const card = {
  id: 'card', background: col('tint'), borderRadius: mm(4),
  padding: { top: mm(4), right: mm(5), bottom: mm(5), left: mm(5) },
  marginTop: mm(HEAD), marginBottom: mm(NEXT), // NEXT: under a card, to whatever follows
  // Off the grid, or what follows a card drops to the next grid line. Only the outer card can
  // set it: a nested box ignores snapToGrid, span and placement (gotcha: nested-callout-limits).
  snapToGrid: false,
  body: { paragraphSpacing: false }, // the boxes' margins do all the spacing
  lists: { bulletChar: '', // no bullet: in the checklist a circle chip opens each item
    gap: mm(2), itemSpacing: pt(7) }, columnGap: mm(6),
};
// A nested box's margins collapse with its neighbours', the larger winning (ASK, AFTER); the
// last box's marginBottom falls inside the card's padding instead of adding to it.
const nested = (id, look) => ({ id, background: col('paper'), borderRadius: mm(2.5),
  marginTop: mm(ASK), marginBottom: mm(AFTER), ...look });
const answer = nested('answer', { border: { enabled: true, color: col('rule'), width: pt(0.75) },
  padding: { top: mm(1.6), right: mm(3), bottom: mm(2), left: mm(3) },
  // A small grey prompt on a full 17 pt line; :::space counts in these body lines.
  body: { fontFamily: LABEL, fontSize: pt(8), color: col('muted') } });
const bank = nested('bank', { title: t({ en: 'Word bank', es: 'Banco de palabras' }),
  padding: { top: mm(2.2), right: mm(3), bottom: mm(2.4), left: mm(3) },
  titleStyle: { fontFamily: LABEL, fontSize: pt(7.5), fontWeight: 600, color: col('leaf'),
    textTransform: 'uppercase', letterSpacing: pt(1.3), gap: mm(1.6) } });
// config() plugs in all three: calloutStyles: [card, answer, bank].
// #endregion

// #region chips: words to pick, blanks to fill, dots to join, circles to colour
const chip = (id, fill, look) => ({ id, fontFamily: LABEL, background: col(fill),
  borderWidth: pt(0), borderColor: col('leaf'), borderRadius: em(1), ...look });
// An empty chip holds a U+2060 word joiner, as one of spaces prints its markup (gotcha:
// empty-chip). Its box is a band 1.25 em tall, so paddingX ROUND makes it a circle.
const [EMPTY, ROUND, OUTLINE] = ['\u2060', em(0.625), pt(0.9)];
// A blank is all padding, 2 × paddingX wide and 19.6 pt tall: taller than the 17 pt line, so
// the card's itemSpacing sets its items 24 pt apart (gotcha: chip-overlap).
const blank = (id, width) => chip(id, 'paper', { borderWidth: OUTLINE, borderRadius: mm(1.4),
  paddingX: mm(width / 2), paddingY: em(0.12), fontSize: em(1.15) });
const chipStyles = [
  chip('word', 'sun', { bold: true, paddingX: em(0.6), paddingY: em(0.08), gap: em(0.45) }),
  blank('blank', 34), blank('wide', 38), // mm: in a sentence; alone in a column
  chip('dot', 'leaf', { paddingX: ROUND, fontSize: em(0.6) }),
  chip('tick', 'paper', { borderWidth: OUTLINE, paddingX: ROUND, fontSize: em(1.1), gap: em(0.5) }),
];
// #endregion

// #region activity: an in-column H2 design: the automatic number in a green disc
const DISC_H2 = 8.6; // mm: the disc and the title are this tall, so the heading reserves this
const numberDisc = { kind: 'text', id: 'num', content: '{number}', // numberingTemplate '{2}'
  fontFamily: DISPLAY, fontSize: pt(15), fontWeight: 800, color: col('paper'),
  box: { backgroundColor: col('leaf'), borderRadius: mm(DISC_H2 / 2) }, // centred both ways
  placement: { anchor: { to: 'container', edge: 'top-left' },
    size: { width: mm(DISC_H2), height: mm(DISC_H2) } } };
const activityTitle = { kind: 'text', id: 'title', content: '{titleText}',
  fontFamily: DISPLAY, fontSize: pt(17), fontWeight: 700, color: col('ink'), align: 'left',
  overflow: 'wrap', placement: { anchor: { to: '#num', edge: 'right-of' },
    offset: { x: mm(3) }, size: { width: mm(140), height: mm(DISC_H2) } } };
const activity = { enabled: true, slot: { elements: [numberDisc, activityTitle] } };
// ## How did I do? {style="review"} is not an activity: it has no number and a star for a disc.
const review = { id: 'review', numbered: false, advancedDesign: { ...activity, slot: {
  elements: [{ kind: 'image', id: 'num', resourceId: 'star', placement: numberDisc.placement },
    activityTitle] } } };
// #endregion

const [BAND, AIR, DOT] = [76, 5, 6]; // mm: the opener's band, air under the disc, dot size
const DISC = { x: 108, y: 5, d: 78 }; // mm: the drawing's disc on the page
const at = (x, y, size, edge = 'top-left') => ({ anchor: { to: 'page', edge },
  offset: { x: mm(x), y: mm(y) }, size });
const words = (id, content, family, size, weight, placement, extra) => ({ kind: 'text', id,
  content, fontFamily: family, fontSize: pt(size), fontWeight: weight, color: col('paper'),
  align: 'left', overflow: 'wrap', placement, ...extra });
const tag = { textTransform: 'uppercase', letterSpacing: pt(1.3) };
const dot = ([n, x, y]) => words(`dot${n}`, String(n), DISPLAY, 10.5, 800, at(DISC.x + x - DOT / 2,
  DISC.y + y - DOT / 2, { width: mm(DOT), height: mm(DOT) }), { color: col('ink'), align: 'center',
  box: { backgroundColor: col('sun'), borderRadius: mm(DOT / 2) } }); // a yellow disc per number
const field = (id, label, x, w) => [words(`${id}-label`, label, LABEL, 7.5, 600, at(x, 59), tag),
  { kind: 'box', id, style: { backgroundColor: col('paper'), borderRadius: mm(1.6) },
    placement: at(x, 63, { width: mm(w), height: mm(7.5) }) }]; // a label over a white field
// Images reserve no height in an opener (gotcha: opener-image-no-reserve), so minHeight does.
const opener = () => ({ enabled: true, minHeight: mm(DISC.y + DISC.d + AIR - TOP),
  slot: { elements: [
    { kind: 'box', id: 'band', style: { backgroundColor: col('leaf') },
      placement: at(0, 0, { height: mm(BAND) }) },
    { kind: 'image', id: 'plant', resourceId: 'plant',
      placement: at(DISC.x, DISC.y, { width: mm(DISC.d), height: mm(DISC.d) }) },
    ...LABELS.map(dot),
    words('unit', '{attr.unit}', LABEL, 9, 600, at(SIDE, TOP - 4), { ...tag, color: col('ink'),
      box: { backgroundColor: col('sun'), borderRadius: mm(3),
        padding: { top: mm(1), right: mm(2.6), bottom: mm(1), left: mm(2.6) } } }),
    words('title', '{titleText}', DISPLAY, 40, 800, at(SIDE, 23.5, { width: mm(88) }),
      { lineHeight: 0.98 }), // two lines: the headings break with \\
    words('series', '{title} · {subtitle} · {attr.sheet}', LABEL, 9.5, 500, at(SIDE, 53)),
    ...field('name', t({ en: 'Name', es: 'Nombre' }), SIDE, 58),
    ...field('date', t({ en: 'Date', es: 'Fecha' }), SIDE + 62, 22),
  ] } });

// #region tables: a rounded panel with a picture in each row and chips to join
const tableStyles = [{ id: 'match', borderRadius: mm(3), // no header row, so no header fill
  headerBackgroundEnabled: false, bodyBackgroundEnabled: true, bodyBackground: col('paper'),
  bodyFontFamily: LABEL, bodyFontSize: pt(13), bodyColor: col('ink'), cellPadding: mm(1.4),
  // White rules on the white panel: unseen, but they hide the canvas's seams between cells.
  rules: 'grid', borderColor: col('paper'), borderWidth: pt(1) }];
const cell = (content, extra) => ({ content, verticalAlign: 'middle', ...extra });
const dotCell = () => cell(`:chip[${EMPTY}]{style="dot"}`, { align: 'center' });
const matchRow = (icon, food, part) => [cell('', { image: { resourceId: icon, width: 0.76 },
  align: 'center' }), cell(food), dotCell(), cell(''), dotCell(),
cell(`:chip[${part}]{style="word"}`)];
const sheetType = { id: 'sheet', name: 'Worksheet item', shortLabel: '', captionPrefix: '',
  numberingTemplate: '{n}', resetOn: 'never', counterFormat: 'decimal' }; // no caption, no number
// Set 'here' in its card, after a :::space (gotcha: box-embed-no-gap); built once FOODS exist.
const foods = () => ({ id: 'foods', typeId: 'sheet', kind: 'table', createdAt: 0, updatedAt: 0,
  placement: { position: 'here' }, table: { styleId: 'match', model: {
    columnWidths: [0.14, 0.25, 0.06, 0.31, 0.06, 0.18], // the widest gap: room to draw a line
    rows: FOODS.map((name, r) => matchRow(ICONS[r], name, PARTS[r])) } } });
// #endregion

const config = () => ({ // a factory, never a shared object (gotcha: config-cache-identity)
  locale: t({ en: 'en-us', es: 'es' }), // exact codes only (gotcha: hyphenation-locales)
  resourceTypes: [sheetType], colorPalette, chipStyles, tableStyles, header: { elements: [] },
  footer: { elements: [words('foot', '{title} · {subtitle} · {attr.unit} · {pageNumber}', LABEL,
    7.8, 600, at(SIDE, -11, undefined, 'bottom-left'), { ...tag, color: col('muted') })] },
  page: { width: mm(200), height: mm(260), dpi: 150, margins: { top: mm(TOP), bottom: mm(20),
    left: mm(SIDE), right: mm(SIDE) } }, layout: { layoutType: 'single' },
  bodyText: { fontFamily: TEXT, fontSize: pt(12), lineHeight: pt(17), color: col('ink'),
    boldColor: col('ink'), italicColor: col('ink'), referenceColor: col('ink'),
    textAlign: 'left', firstLineIndent: pt(0), paragraphSpacing: true },
  // #region grid: the headings leave the grid too, and nothing stretches the gaps
  headings: { fontFamily: DISPLAY, snapToGrid: false, // or what follows snaps back to the grid
    balancing: { enabled: false }, // no extra space above headings to fill out a page
    levels: [
      // Restated: any headings object drops the H1 break (gotcha: headings-drop-h1-break).
      { level: 1, span: 'page', breakBefore: { enabled: true, parity: 'any' },
        marginTop: pt(0), marginBottom: pt(0), advancedDesign: opener() },
      { level: 2, numberingTemplate: '{2}', marginTop: mm(0), marginBottom: mm(0),
        advancedDesign: activity },
    ] },
  // #endregion
  orderedLists: { fontFamily: DISPLAY, fontWeight: 800, marginTop: mm(ASK), // a bank's AFTER wins
    numberVerticalOffset: pt(1.7) }, // centred 0.3 em over the baseline, Baloo 2 sat high
  headingStyles: [review], calloutStyles: [card, answer, bank],
  paragraphStyles: [{ id: 'lead', fontSize: pt(14), lineHeight: pt(20) }, { id: 'colophon',
    fontFamily: LABEL, fontSize: pt(7.5), lineHeight: pt(10), color: col('muted') }],
});

// ─── 2 · Content ────────────────────────────────────────────────────────────
const markdown = String.raw`---
Markdown样例 · 119行 · content.en.md
title: "Seedlings Science"
subtitle: "Year 4"
---

# Plants and \\ their parts {unit="Unit 3" sheet="Worksheet 3A"}

:::paragraphs{style="lead"}
Every part of a plant has a job to do. In this worksheet you will name the parts of a pea plant and find out what each one does and which ones we eat. You will need a pencil and some coloured pencils.
:::

## Look closely

:::callout{type="card"}
What is inside the pea pods on the plant at the top of the page?

:::callout{type="answer"}
Write here
:::space{lines=4}
:::

Which part of the plant grows under the ground? Why does the plant need it?

:::callout{type="answer"}
Write here
:::space{lines=6}
:::
:::

## Name the parts

:::callout{type="card"}
Six parts of the pea plant on page 1 have a number. Choose a word from the word bank and write it next to the same number.

:::callout{type="bank"}
:chip[stem]{style="word"} :chip[seeds]{style="word"} :chip[flower]{style="word"} :chip[roots]{style="word"} :chip[leaf]{style="word"} :chip[fruit]{style="word"}
:::

:::columns{count=3}
1. :chip[⁠]{style="wide"}
2. :chip[⁠]{style="wide"}
3. :chip[⁠]{style="wide"}
4. :chip[⁠]{style="wide"}
5. :chip[⁠]{style="wide"}
6. :chip[⁠]{style="wide"}
:::
:::

## What does each part do?

:::callout{type="card"}
Finish each sentence with a word from the word bank.

:::callout{type="bank"}
:chip[food]{style="word"} :chip[insects]{style="word"} :chip[water]{style="word"} :chip[plant]{style="word"} :chip[upright]{style="word"} :chip[seeds]{style="word"}
:::

1. The **roots** hold the plant in the soil and take in :chip[⁠]{style="blank"}.
2. The **stem** keeps the plant :chip[⁠]{style="blank"} and carries water to the leaves.
3. The **leaves** use sunlight to make :chip[⁠]{style="blank"} for the plant.
4. The **flower** has bright petals that attract :chip[⁠]{style="blank"} such as bees.
5. The **fruit** grows around the :chip[⁠]{style="blank"} and keeps them safe.
6. A **seed** can grow into a new :chip[⁠]{style="blank"}.
:::

**Did you know?** A pea plant cannot stand up on its own. It climbs by wrapping thin, curly tendrils around anything it touches.

## Parts we eat

:::callout{type="card"}
We eat many different plant parts. Draw a line from each food to the part of the plant it comes from.

:::space{lines=0.33}
::resource{id="foods"}
:::

## Draw and label

:::callout{type="card"}
Draw a plant you have seen at home or at school. Label at least four of its parts.

:::callout{type="answer"}
My plant is called
:::space{lines=7}
:::
:::

## Try it at home

:::callout{type="card"}
Put a dried pea on some wet cotton wool in a clear jar. Keep the cotton wool damp and look at the pea every day for a week. What do you think will come out of the pea first: a root or a shoot?

:::callout{type="answer"}
I think
:::space{lines=3}
:::

After a week, draw or write what you saw.

:::callout{type="answer"}
I saw
:::space{lines=6}
:::
:::

## How did I do? {style="review"}

:::callout{type="card"}
Colour a circle for each thing you can do.

- :chip[⁠]{style="tick"} I can name the six parts of a plant.
- :chip[⁠]{style="tick"} I can say what each part does.
- :chip[⁠]{style="tick"} I can tell which part of a plant a food comes from.
:::

:::paragraphs{style="colophon"}
Seedlings Science is an invented series made for the Postext Cookbook. Text and drawings: CC BY 4.0.

Set in Andika, Baloo 2 and Fredoka (SIL Open Font License).
:::
`; // content.<lang>.md, inlined by the Cookbook

// The matching table's words. The parts are shuffled so that no food faces its own part.
const FOODS = t({ en: 'carrot|asparagus|lettuce|broccoli|orange|kidney beans',
  es: 'zanahoria|espárrago|lechuga|brócoli|naranja|alubias' }).split('|');
const PARTS = t({ en: 'leaf|seeds|root|fruit|stem|flower',
  es: 'hoja|semillas|raíz|fruto|tallo|flor' }).split('|');

// #region art: the pea plant, the six foods and the star, in the palette's colours
// No words in them: an SVG drawn as an image cannot use web fonts (gotcha: svg-no-webfonts);
// the plant's numbers are design elements set in Baloo 2 over the drawing (see the band).
// [number, x, y] in the disc's millimetres: each numbered dot, where its leader line starts.
const LABELS = [[1, 58, 8], [2, 68, 33], [3, 9, 44], [4, 13, 20], [5, 62, 52], [6, 18, 66]];
const n = (v) => +v.toFixed(2);
const svgDoc = (w, h, body, scale = 10) => `<svg xmlns="http://www.w3.org/2000/svg" `
  + `width="${w * scale}" height="${h * scale}" viewBox="0 0 ${w} ${h}">${body}</svg>`;
const circle = (x, y, r, fill, extra = '') => `<circle cx="${n(x)}" cy="${n(y)}" r="${n(r)}" `
  + `fill="${fill}"${extra}/>`;
const path = (d, fill, extra = '') => `<path d="${d}" fill="${fill}"${extra}/>`;
const stroke = (d, color, width) => path(d, 'none', ` stroke="${color}" stroke-width="${width}" `
  + 'stroke-linecap="round" stroke-linejoin="round"');
const leafShape = (x, y, len, wid, turn, fill, vein) => `<g transform="translate(${n(x)} `
  + `${n(y)}) rotate(${n(turn)})">${path(`M0 0C${n(len * 0.3)} ${n(-wid)} ${n(len * 0.8)} `
  + `${n(-wid)} ${n(len)} 0C${n(len * 0.8)} ${n(wid)} ${n(len * 0.3)} ${n(wid)} 0 0Z`, fill)}`
  + `${vein ? stroke(`M${n(len * 0.12)} 0L${n(len * 0.8)} 0`, vein, 0.35) : ''}</g>`;
function plant() { // a pea plant in a white disc, its roots in a slice of soil
  const [c, r, ground] = [39, 39, 58];
  const dx = Math.sqrt(r * r - (ground - c) ** 2);
  let out = circle(c, c, r, palette.paper);
  out += path(`M${n(c - dx)} ${ground}Q20 ${ground - 2.2} 39 ${ground}T${n(c + dx)} ${ground}`
    + `A${r} ${r} 0 0 1 ${n(c - dx)} ${ground}Z`, palette.soil);
  for (const [x, y, rr] of [[22, 70, 0.9], [55, 66, 0.7], [47, 73, 1.1], [26, 62, 0.6]]) {
    out += circle(x, y, rr, palette.paper, ' fill-opacity=".25"');
  }
  out += stroke('M39 58C38 63 36 66 33 70M39 58C40 64 43 67 46 71M38 62C35 63 31 63 27 65'
    + 'M40 63C44 63 48 62 52 63M36 66C35 69 34 72 34 75M44 68C45 71 46 73 45 76',
  palette.paper, 0.7); // roots
  out += stroke('M39 58C37 50 42 44 39 36S37 22 41 11', palette.leaf, 1.5); // the stem
  for (const [y, s] of [[49, 1], [39, -1], [28, 1], [19, -1]]) { // leaflets in pairs
    out += leafShape(39, y, 12, 3.6, s > 0 ? -28 : -152, palette.leaf, palette.tint);
    out += leafShape(39, y + 2, 10, 3.2, s > 0 ? -160 : -20, palette.leaf, palette.tint);
  }
  out += stroke('M41 12c2.5-1 4.6.4 4.2 2.6s-3 2.2-3.4.2 1.8-1.8 2.4-.4M39 27c-2.6-1.4-5.4-.6-5.2 '
    + '1.6s2.8 2.4 3.4.6-1.4-2-2.2-.8M40 38c2.8-.8 5.2.6 4.6 2.6', palette.leaf, 0.45); // tendrils
  // A closed pod (the fruit) on the right, its peas showing through; an open one (the seeds).
  const calyx = (x, y, turn) => `<g transform="translate(${x} ${y}) rotate(${turn})">`
    + path('M0 0L1.6-1.2 1.2.4 2.4 1.2.6 1.4Z', palette.leaf) + '</g>';
  out += stroke('M40 31.5Q42 31 43.4 32', palette.leaf, 0.5)
    + path('M43 31.6C48 30.8 54 32.4 57.6 37.8C53 38.6 47.4 36.8 43 31.6Z', palette.rule,
      ` stroke="${palette.leaf}" stroke-width=".5"`)
    + [[46.4, 33.4], [49.6, 34.8], [52.8, 36.1]].map(([x, y]) => circle(x, y, 1.15,
      palette.leaf, ' fill-opacity=".35"')).join('') + calyx(42.6, 31.8, -10);
  out += stroke('M38 36Q37 36 36.2 36.4', palette.leaf, 0.5)
    + path('M36 36C30 37 23 40 20 45C25 47 33 43 36 36Z', palette.tint,
      ` stroke="${palette.leaf}" stroke-width=".5"`)
    + stroke('M35.4 36.6C31 39.6 26 42.6 20.6 44.8', palette.leaf, 0.3) + calyx(36.4, 36.4, 160);
  for (const [x, y] of [[32.6, 39.4], [29.8, 41], [27, 42.5], [24.2, 43.9]]) {
    out += circle(x, y, 1.25, palette.leaf);
  }
  // Pea flowers, seen from the front: white, as a garden pea's are, outlined in green.
  for (const [x, y, turn] of [[42, 9, -18], [48, 20.5, 24]]) {
    const edge = ` stroke="${palette.leaf}" stroke-width=".4"`;
    out += `<g transform="translate(${x} ${y}) rotate(${turn})">`
      + stroke('M0 2.6L0 4.6', palette.leaf, 0.5) + path('M-1.1 1.1L0 3 1.1 1.1Z', palette.leaf)
      + path('M0 0C-4.2-.6-5.2-6.4-1.6-7.2C-.8-7.4-.2-6.8 0-6.2C.2-6.8.8-7.4 1.6-7.2'
        + 'C5.2-6.4 4.2-.6 0 0Z', palette.paper, edge) // the standard petal
      + path('M-2.6-1.4C-3.4 1.2-1 2.6 0 1.4C1 2.6 3.4 1.2 2.6-1.4C1.4-.4-1.4-.4-2.6-1.4Z',
        palette.tint, edge) + stroke('M0-1.2L0-5', palette.rule, 0.3) + '</g>'; // the wings
  }
  // Where each leader ends: 2 on the pod's wall past its last pea (the fruit), 3 on a pea in
  // the open pod (the seeds), 4 in the middle of a leaf's blade, well clear of the stem.
  const targets = { 1: [43, 5.6], 2: [55.5, 36.6], 3: [27, 42.5], 4: [33.2, 15.9],
    5: [39.4, 47], 6: [36.7, 64.4] };
  for (const [num, x, y] of LABELS) { // leader lines from each dot to its part
    const [tx, ty] = targets[num];
    out += stroke(`M${x} ${y}L${tx} ${ty}`, palette.ink, 0.35) + circle(tx, ty, 0.7, palette.ink);
  }
  return svgDoc(78, 78, out);
}
function star() { // the self-check's badge: a white star on a sun disc
  const pts = Array.from({ length: 10 }, (_, i) => {
    const a = -Math.PI / 2 + (i * Math.PI) / 5;
    const rr = i % 2 ? 4.4 : 9.4;
    return `${n(12 + Math.cos(a) * rr)} ${n(12.6 + Math.sin(a) * rr)}`;
  });
  return svgDoc(24, 24, circle(12, 12, 12, palette.sun) + path(`M${pts.join('L')}Z`,
    palette.paper), 10);
}
const food = {
  carrot: () => path('M3.5 17.5C8 13 12 8.5 16.2 5.2C18 4 20.6 6.4 19.2 8.2C15.8 12.4 10 15.8 '
    + '3.5 17.5Z', palette.sun) + stroke('M8 13.6l1.4 1.2M11.6 10.6l1.3 1.3M14.6 8l1.2 1.2',
    palette.soil, 0.4) + [-120, -80, -40].map((a) => leafShape(18.4, 6.4, 6, 1.4, a,
    palette.leaf)).join(''),
  asparagus: () => [[10, 7], [12, 12], [14, 17]].map(([x0, x1]) => path(`M${x0 - 1.3} 19`
    + `L${x1 - 1} 5Q${x1} 1.4 ${x1 + 1} 5L${x0 + 1.3} 19Z`, palette.leaf) + stroke(`M${x1 - 0.8} `
    + `7.6l.8.8.8-.8M${(x0 + x1) / 2 - 0.9} 11.4l.9.9.9-.9`, palette.tint, 0.35)).join('')
    + path('M7.8 13.4h8.4v2.2H7.8Z', palette.sun),
  lettuce: () => { // a head seen from the side: two dark outer leaves cupping a pale heart
    const side = path('M13 19C6 19 2.6 15 3 9.6C3.2 7.4 4.6 6 5.8 7C6.2 5.4 7.8 4.8 8.6 6.2'
      + 'C9.4 5.2 10.6 5.6 10.6 6.8C9 10 9.4 15 13 19Z', palette.leaf)
      + stroke('M11 17.6C7.6 16 5.2 12.6 5.2 8.6', palette.tint, 0.4); // a frilled leaf, its vein
    return `<ellipse cx="12" cy="11.4" rx="5.8" ry="6.8" fill="${palette.rule}"/>`
      + stroke('M12 17.6C11.6 14 11.8 10 12.8 6', palette.tint, 0.45)
      + side + `<g transform="translate(24 0) scale(-1 1)">${side}</g>`;
  },
  broccoli: () => path('M10 19l1-7h2l1 7Z', palette.rule) + [[8, 9, 3.4], [12, 7, 3.8],
    [16, 9, 3.4], [10, 11.5, 2.6], [14, 11.5, 2.6]].map(([x, y, rr]) => circle(x, y, rr,
    palette.leaf)).join(''),
  orange: () => circle(12, 11.5, 7.5, palette.sun) + leafShape(12, 4.2, 5, 1.6, -30,
    palette.leaf) + circle(9, 9, 1.2, palette.paper, ' fill-opacity=".45"'),
  beans: () => [[7, 13, -20], [13, 9, 15], [16, 15, -35]].map(([x, y, a]) => `<g transform=`
    + `"translate(${x} ${y}) rotate(${a})">${path('M-4 0C-4 -3 -1 -3 0 -1.5C1 -3 4 -3 4 0'
    + 'C4 3 -4 3 -4 0Z', palette.soil)}</g>`).join(''),
};
const ICONS = Object.keys(food); // carrot … beans: the matching table's rows, in order
const drawings = { plant, star,
  ...Object.fromEntries(Object.entries(food).map(([id, draw]) => [id, () => svgDoc(24, 20,
    draw())])) };
const ALT = { ...Object.fromEntries(ICONS.map((id, i) => [id, FOODS[i]])),
  plant: t({ en: 'A pea plant with its flower, pod, peas, leaf, stem and roots numbered 1 to 6',
    es: 'Una planta de guisante con la flor, la vaina, los guisantes, la hoja, el tallo y las '
      + 'raíces numerados del 1 al 6' }),
  star: t({ en: 'A white star on a yellow disc',
    es: 'Una estrella blanca en un disco amarillo' }) };
// Each drawing is a resource that the opener, a table cell or the review heading names by
// id. None is cited, so none is placed as a figure. Sizes in px, 10 to the millimetre.
const pictures = Object.keys(drawings).map((id) => ({ id, typeId: 'sheet', kind: 'svg',
  altText: ALT[id], createdAt: 0, updatedAt: 0, svg: { fileId: `${id}.svg`,
    width: 240, height: 200,
    ...{ plant: { width: 780, height: 780 }, star: { width: 240, height: 240 } }[id] } }));
// #endregion

const resources = [...pictures, foods()];

// ─── 3 · Fonts ──────────────────────────────────────────────────────────────
const FONTS = { Andika: ['400', '700'], 'Baloo 2': ['700', '800'], // (gotcha: fonts-first)
  Fredoka: ['400', '500', '600', '700'] };

// ─── 4 · Build & show ───────────────────────────────────────────────────────
await Promise.all([loadFonts(FONTS, markdown),
  ...Object.entries(drawings).map(([id, draw]) => loadSvg(`${id}.svg`, draw()))]);
const doc = await buildWithFonts(() => buildDocument({ markdown, resources }, config()), markdown);
showPages(doc, { title: t({ en: 'Plants and their parts', es: 'Las plantas y sus partes' }) });

工具包 · core, fonts, viewer, images：每道食谱都相同 · 270行
// ─── 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 v1 ── the same in every recipe · postext.dev/cookbook ────────
// Postext measures text with the faces the browser has loaded, and caches the
// widths, so every face must be ready before the first build. Faces come from
// Fontsource: the same static files the PDF embeds, so screen and PDF agree.

/** faces = { 'Family Name': ['400', '400i', '700'] }. `text` is the sample:
 *  letters beyond Latin-1 (č, ł, ő…) also load the latin-ext files. With
 *  `optional`, a face Fontsource does not ship is skipped instead of failing.
 *  Resolves to the number of faces added. */
async function loadFonts(faces, text = '', { optional = false } = {}) {
  kitStatus('Loading fonts…');
  const ranges = {
    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',
  };
  const subsets = /[Ā-˿Ḁ-ỿ]/.test(text) ? ['latin', 'latin-ext'] : ['latin'];
  const jobs = [];
  let added = 0;
  for (const [family, specs] of Object.entries(faces)) {
    const id = fontsourceId(family);
    const meta = optional ? await fontsourceMeta(family) : null;
    for (const spec of new Set(specs)) {
      const weight = parseInt(spec, 10);
      const style = spec.endsWith('i') ? 'italic' : 'normal';
      if (hasFace(family, weight, style)) continue;
      if (optional && !(meta?.weights.includes(weight) && meta.styles.includes(style))) continue;
      for (const subset of subsets) {
        const url = `https://cdn.jsdelivr.net/npm/@fontsource/${id}@5/files/${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().then((ready) => { document.fonts.add(ready); added++; }, () => {
          if (subset === 'latin' && !optional) throw new Error(`Fontsource has no ${family} ${weight} ${style}`);
        }));
      }
    }
  }
  await Promise.all(jobs).catch((error) => { kitFail(error); throw error; });
  return added;
}

/** Runs `build` (a buildDocument or buildBundle call) and checks the faces
 *  the pages use. A regular face missing from FONTS is loaded with a warning;
 *  bold and italic variants are loaded when the family ships them. Then the
 *  measurement caches are cleared and the build runs again. */
async function buildWithFonts(build, text = '') {
  const tried = new Set();
  for (let round = 0; round < 3; round++) {
    kitStatus('Laying out…');
    await new Promise(requestAnimationFrame);          // let the status paint first
    const result = await Promise.resolve().then(build).catch((error) => { kitFail(error); throw error; });
    const wanted = { base: {}, variants: {} };
    for (const { font, base } of [result].flat().flatMap(fontStringsOf)) {
      const { family, weight, style } = parseFont(font);
      const key = `${family}|${weight}|${style}`;
      if (tried.has(key) || hasFace(family, weight, style)) continue;
      tried.add(key);
      (wanted[base ? 'base' : 'variants'][family] ??= []).push(`${weight}${style === 'italic' ? 'i' : ''}`);
    }
    if (Object.keys(wanted.base).length) {
      console.warn(`[cookbook] FONTS does not list ${JSON.stringify(wanted.base)}: loading them.`);
    }
    const added = await loadFonts(wanted.base, text) + await loadFonts(wanted.variants, text, { optional: true });
    if (added === 0) return result;
    clearMeasurementCache();
  }
  throw new Error('The fonts did not settle after three builds.');
}

/** Every font string of the layout. `base` marks a block's own face; its
 *  bold, italic and bold-italic variants are listed whether or not used. */
function fontStringsOf(doc) {
  const found = new Map();
  const walk = (node) => {
    if (!node || typeof node !== 'object') return;
    if (Array.isArray(node)) { node.forEach(walk); return; }
    for (const [key, value] of Object.entries(node)) {
      if (typeof value === 'string' && /fontString$/i.test(key)) {
        found.set(value, found.get(value) || key === 'fontString');
      } else if (value && typeof value === 'object') walk(value);
    }
  };
  walk(doc.pages);
  walk(doc.blocks);
  return [...found].map(([font, base]) => ({ font, base }));
}

/** '700 37.5px Open Sans' / 'italic 400 13px "Source Serif 4"' → { family, weight, style }.
 *  A string with no weight ('95.8px Young Serif', from a design text) is 400. */
function parseFont(font) {
  const m = /^(?:(italic|oblique)\s+)?(?:small-caps\s+)?(?:(\d+|bold|normal)\s+)?[\d.]+px\s+(.+)$/.exec(font.trim());
  if (!m) throw new Error(`Unexpected font string: ${font}`);
  const weight = m[2] === 'bold' ? 700 : !m[2] || m[2] === 'normal' ? 400 : Number(m[2]);
  return { family: m[3].replace(/^["']|["']$/g, ''), weight, style: m[1] ? 'italic' : 'normal' };
}

/** True when a loaded FontFace covers exactly this family, weight and style
 *  (document.fonts.check() is also true for families nobody declared). */
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;
}

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

/** The weights and styles a family ships ({ weights: [400, 700], styles: ['normal', 'italic'] }), or null. */
function fontsourceMeta(family) {
  fontsourceMeta.cache ??= new Map();
  const id = fontsourceId(family);
  if (!fontsourceMeta.cache.has(id)) {
    fontsourceMeta.cache.set(id, fetch(`https://api.fontsource.org/v1/fonts/${id}`)
      .then((res) => (res.ok ? res.json() : null), () => null));
  }
  return fontsourceMeta.cache.get(id);
}

// ─── Kit · viewer v1 ── the same in every recipe · postext.dev/cookbook ───────
/** Shows the pages as facing spreads on a dark desk: the first page is a
 *  recto on its own, then verso | recto pairs, as in a bound book. Pages
 *  are painted when they scroll near the screen. */
function showPages(docs, { title, width = 460 } = {}) {
  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, { 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 · images v1 ── 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 (drawn in code, or fetched) as a vector image. */
async function loadSvg(fileId, svg) {
  const img = new Image();
  img.src = `data:image/svg+xml;charset=utf-8,${encodeURIComponent(svg)}`;
  await img.decode();
  registerResourceImage(fileId, img);
  (loadImage.bytes ??= new Map()).set(fileId, new TextEncoder().encode(svg));
}

/** 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 ───────────────────────────────────────────────────────────────────────

组合好的script.js可以直接运行：把它粘贴到任何页面的模块脚本中，或在CodePen上打开这道食谱。 GitHub上的食谱文件夹 ↗

变化

#让卡片回到网格上

使用默认的snapToGrid: true时，卡片后面的内容会落到下一条17 pt网格线上，每张卡片下方的9 mm在活动2下变成14.5 mm，在活动4下变成13.2 mm，在活动6下变成11.2 mm。

-  snapToGrid: false,
+  snapToGrid: true,

#给答案更多空间

:::space按答题框自己的17 pt行计数，每多一行，学生就多6 mm的书写空间。

 Write here
-:::space{lines=4}
+:::space{lines=6}

常见问题

易错点

:::space在框顶或栏顶会被丢掉

:::space出现在栏顶、框顶或:::columns组顶部时会被丢掉，即使它是框里唯一的内容，所以只由空白组成的答题框会塌掉。框以标题或一行提示开头，再加空白。显式竖向间距 →

易错点

只含空白的行内标签会打印出标记

文字只有空格（包括不换行空格）的行内标签，会按原样打印出:chip[ ]。要做空白的答题标签，在里面放一个连接符（U+2060）。行内标签 →

易错点

嵌套框忽略span、placement和snapToGrid

嵌套在另一个标注框中的标注框会忽略自己的span、placement、snapToGrid和floatBarrier：它总是在父框内部排，宽度为父框的内宽。嵌套框 →

易错点

高于行距的行内标签会碰到下一行

框高超过行距的行内标签会碰到下一行的行内标签（chipOverlap警告）。减小它的上下内边距、边框或字号，或者加大行距。行内标签 →

易错点

框内的表或图四周没有间距

在postext 1.4.1中，::resource在:::callout里以位置'here'排入的表或图，得不到它在正文中享有的间距：上下紧贴前后两段。在::resource这一行之前放一个:::space，后面还有文字时再在其后放一个；取一行的几分之一（如lines=0.33）就能留出一道小间隙。图就放在这里 →

易错点

章首页的图片从不计入它预留的高度

在postext 1.4.1中，高级设计标题计算预留高度时不算其中的图片：文字、线条和框都计入，即使它们锚定在页面上；但图片（例如出血铺满页面顶部的图）不预留任何空间，所以正文可能排到它上面。把minHeight设为正文应当开始的位置。设计过的章首页 →

易错点

传入任何headings对象都会关掉H1换页

默认情况下，H1换页到右页（always-odd），但只要传入headings对象，这个默认值就会被重置，于是各章接排，span: 'page'也不起作用。在每份配置中重新写明headings.levels[0].breakBefore: { enabled: true, parity }。从右页开始的章 →

易错点

SVG <img>中的文字不能使用网络字体

SVG作为图像绘制，而图像无法使用页面的网络字体，所以其中的标签会退回系统字体。把文字转成轮廓，在SVG中嵌入@font-face子集，或者把标签移到题注里。作为资源的图和表 →

易错点

替换调色板时，设计元素和引用颜色不会跟着变

postext 1.4.1把colorPalette读入文字样式（正文、标题、列表、题注、表格、框），但不读入页眉、页脚、章首页和篇章页的元素，也不读入bodyText.referenceColor：它们保留写在paletteId旁边的十六进制颜色。替换调色板时（例如做深色屏幕版或换色），在构建前根据colorPalette重写每一个关联的颜色。语义调色板 →

易错点

只有8种语言区域能断词，且须代码完全一致

断词支持en-us、es、fr、de、it、pt、ca和nl，须完全匹配：'es-ES'或其他任何语言都会悄悄退回美式英语。断词与文档语言 →

易错点

配置按对象身份缓存：每次新建一个对象

引擎按对象身份缓存解析后的配置，所以就地修改配置再构建，会复用旧的结果。每次构建都新建一个对象，这也是食谱的配置写成工厂函数config()的原因。在Canvas上绘制页面 →

易错点

排版前加载所有字体

排版用浏览器已加载的字体测量文字，并缓存宽度，所以首次构建之后才到的字体会造成断行错误，PDF也不再与屏幕一致。先加载所有字重和样式；有字体迟到时，重新构建前调用clearMeasurementCache()。排版前加载字体 →

沙盒检查 · chipOverlap

行内标签碰到下一行

原因. 某个行内标签样式的框比行距还高，因此相邻两行的标签会相碰。

解决. 减小标签的竖向内边距、轮廓或尺寸，或加大行距。文档 →

在postext 1.4.1中，框不能给自己画书写横线，因为标注框样式没有横线背景。答题框保持空白，高度由:::space决定，短的填空线则用描边的行内标签。
带numbered: false的标题样式仍会画出该级的版面设计，只是{number}为空。如果没有自己的版面设计，自我检查会以一个空的绿色圆盘开头，所以review复制了活动的版面设计，把星星放在原来圆盘的位置。

致谢

食谱: Ignacio Ferro
文本: 原创文字, CC BY 4.0
字体: Andika (SIL OFL 1.1) · Baloo 2 (SIL OFL 1.1) · Fredoka (SIL OFL 1.1)
代码: MIT，与Postext相同

编辑这篇说明 ↗GitHub上的食谱文件夹 ↗

带答题框和词库的练习单

成品一览

简短回答

用料

做法

#1 · 标题也脱离网格

#2 · 每个空都用行内标签

#3 · 用标题的版面设计给活动编号

#4 · 把图片放进表格单元格

完整食谱

变化

#让卡片回到网格上

#给答案更多空间

常见问题

致谢

#成品一览

#简短回答

#用料

#做法

#1 · 标题也脱离网格

#2 · 每个空都用行内标签

#3 · 用标题的版面设计给活动编号

#4 · 把图片放进表格单元格

#完整食谱

#变化

#让卡片回到网格上

#给答案更多空间

#常见问题

#致谢

排版食谱中的更多内容

带答题卡的试卷

用音节标签排启蒙识字课本

益智游戏书：填字、找词和迷宫

成品一览

简短回答

用料

做法

完整食谱

变化

常见问题

致谢