{
  "id": "motion:motion-hero-shrink",
  "slug": "motion-hero-shrink",
  "kind": "motion",
  "title": {
    "ja": "ヒーロー縮小",
    "en": "Hero title shrink"
  },
  "aiName": "Hero title shrinks into header",
  "summary": {
    "ja": "大見出しが縮んでヘッダーに収まる",
    "en": "The large title shrinks and settles into the header"
  },
  "number": 39,
  "group": "lp-section",
  "techniques": [
    "position-sticky",
    "scroll-progress"
  ],
  "rules": [
    {
      "ja": "縮む見出しは pin 区画の中に置き、区画が終わるまでの間に着地を終える",
      "en": "The shrinking title sits inside the pinned section and finishes landing before the section ends"
    },
    {
      "ja": "拡大率は 1 から 0.18 の範囲に収め、ヘッダーの文字の大きさと一致させる",
      "en": "Scale stays between 1 and 0.18, and the landed size matches the header text"
    },
    {
      "ja": "動きを減らす設定では見出しを動かさず、ヘッダーに収まった状態だけを表示する",
      "en": "With reduced motion, skip the movement and show only the landed state in the header"
    }
  ],
  "reproduction": {
    "prompt": {
      "ja": "ヒーロー縮小 — Hero title shrinks into header\n\nページ冒頭に画面いっぱいの大見出しを置き、スクロールに合わせてヘッダーの位置へ縮めて収める演出を作ってください。外側の区画は高さ 300vh とし、その中に position: sticky; top: 0 の 100vh の箱を置きます。区画の上端が画面の上端に来たとき p=0、区画の下端が画面の下端に来たとき p=1 として進み具合 p（0〜1）を求めます。見出しは `transform: scale(calc(1 - var(--p) * 0.82))` で 1 から 0.18 まで縮め、同時に画面中央から上端へ移動させて、p=1 でヘッダーのブランド位置（左 24px、高さ 64px のヘッダーの上下中央）に着地させます。ヘッダーは固定の別部品として上端に置き、着地したときだけブランドの文字を表示します。CSS と素の JavaScript だけで実装し、ライブラリは使わないでください。\n\n外すと崩れる点:\n- 縮む見出しは pin 区画の中に置き、区画が終わるまでの間に着地を終える\n- 拡大率は 1 から 0.18 の範囲に収め、ヘッダーの文字の大きさと一致させる\n- 動きを減らす設定では見出しを動かさず、ヘッダーに収まった状態だけを表示する\n\n動く実物（1 ファイルで完結する HTML）: https://design-vault.pages.dev/designs/motion-hero-shrink/demo.html",
      "en": "Hero title shrink — Hero title shrinks into header\n\nStart the page with a full-screen large title that shrinks into the header position as the user scrolls. The outer section is 300vh tall and holds a 100vh box with position: sticky; top: 0. Compute the progress p (0 to 1) as p=0 when the section's top reaches the top of the screen and p=1 when its bottom reaches the bottom. Scale the title with `transform: scale(calc(1 - var(--p) * 0.82))`, shrinking it from 1 to 0.18 while it moves from the middle of the screen to the top edge, so that at p=1 it sits at the header's brand position (24px from the left, vertically centred in the 64px-tall header). The header is a separate fixed bar at the top, and its brand text appears only once the title has landed. Implement with CSS and plain JavaScript only; do not use a library.\n\nDo not drop:\n- The shrinking title sits inside the pinned section and finishes landing before the section ends\n- Scale stays between 1 and 0.18, and the landed size matches the header text\n- With reduced motion, skip the movement and show only the landed state in the header\n\nA working example (one self-contained HTML file): https://design-vault.pages.dev/designs/motion-hero-shrink/demo.html"
    },
    "code": {
      "url": "https://design-vault.pages.dev/designs/motion-hero-shrink/demo.html",
      "html": "<!doctype html>\n<html lang=\"ja\">\n<head>\n<meta charset=\"utf-8\">\n<meta name=\"viewport\" content=\"width=device-width, initial-scale=1\">\n<title>39 ヒーロー縮小 — Hero title shrinks into header</title>\n<style>\n/* dv-motion-base:start */\n:root {\n  --ground: #FFFFFF;\n  --surface: #F3F5F8;\n  --ink: #14181F;\n  --muted: #5A6472;\n  --accent: #1F5FA8;\n  --rule: #D8DDE4;\n  --accent-soft: color-mix(in srgb, var(--accent) 12%, var(--ground));\n  --accent-mid: color-mix(in srgb, var(--accent) 45%, var(--ground));\n  --shade: color-mix(in srgb, var(--ink) 14%, transparent);\n\n  --font: \"Zen Kaku Gothic New\", \"Hiragino Sans\", \"Noto Sans JP\", \"Yu Gothic\", system-ui, sans-serif;\n  --mono: ui-monospace, \"SF Mono\", Menlo, Consolas, monospace;\n\n  --t-label: 13px;\n  --t-body: 16px;\n  --t-lead: 20px;\n  --t-h2: 32px;\n  --t-h1: clamp(40px, 7vw, 72px);\n\n  --s1: 4px;\n  --s2: 8px;\n  --s3: 16px;\n  --s4: 24px;\n  --s5: 40px;\n  --s6: 64px;\n  --s7: 104px;\n\n  --radius: 12px;\n  --ease: cubic-bezier(.2, .7, .2, 1);\n  --dur: .7s;\n  --measure: 1080px;\n}\n*, *::before, *::after { box-sizing: border-box; }\nhtml { -webkit-text-size-adjust: 100%; }\nbody {\n  margin: 0;\n  background: var(--ground);\n  color: var(--ink);\n  font-family: var(--font);\n  font-size: var(--t-body);\n  line-height: 1.7;\n  font-feature-settings: \"palt\";\n  overflow-x: hidden;\n}\nh1, h2, h3, p, ul, ol, figure { margin: 0; padding: 0; }\nul, ol { list-style: none; }\n.dv-wrap { width: min(100% - 2 * var(--s4), var(--measure)); margin-inline: auto; }\n.dv-label {\n  min-height: 72vh;\n  display: grid;\n  align-content: center;\n  gap: var(--s3);\n  padding-block: var(--s6);\n  border-bottom: 1px solid var(--rule);\n}\n.dv-num { font-family: var(--mono); font-size: var(--t-lead); font-weight: 700; color: var(--accent); letter-spacing: .04em; }\n.dv-name { font-size: var(--t-h1); font-weight: 700; line-height: 1.15; letter-spacing: .01em; }\n.dv-ai { font-family: var(--mono); font-size: var(--t-lead); color: var(--muted); }\n.dv-desc { font-size: var(--t-lead); color: var(--ink); }\n.dv-hint { font-size: var(--t-label); color: var(--muted); letter-spacing: .12em; margin-top: var(--s4); }\n.dv-stage { padding-block: var(--s7); }\n.dv-h2 { font-size: var(--t-h2); font-weight: 700; line-height: 1.3; }\n.dv-lead { font-size: var(--t-lead); color: var(--muted); }\n.dv-eyebrow { font-family: var(--mono); font-size: var(--t-label); color: var(--accent); letter-spacing: .12em; text-transform: uppercase; }\n.dv-card { background: var(--surface); border: 1px solid var(--rule); border-radius: var(--radius); padding: var(--s4); }\n.dv-ph {\n  border-radius: var(--radius);\n  background: linear-gradient(135deg, var(--accent-soft), var(--accent-mid) 60%, var(--accent));\n  aspect-ratio: 16 / 9;\n}\n.dv-ph--alt { background: linear-gradient(200deg, var(--surface), var(--accent-soft) 55%, var(--accent-mid)); }\n.dv-ph--ink { background: linear-gradient(160deg, var(--ink), color-mix(in srgb, var(--ink) 55%, var(--accent))); }\n.dv-end {\n  min-height: 60vh;\n  display: grid;\n  place-items: center;\n  border-top: 1px solid var(--rule);\n  color: var(--muted);\n  font-family: var(--mono);\n  font-size: var(--t-label);\n  letter-spacing: .12em;\n}\n/* dv-motion-base:end */\n\n/* ---- この演出だけの CSS。色は var(--…) か color-mix() のみ ---- */\nbody { --hero: min(28vw, 200px); }\n.stack { display: grid; gap: var(--s6); }\n.js .hd-bar { position: fixed; top: 0; left: 0; right: 0; z-index: 10; height: 64px; display: flex; align-items: center; justify-content: space-between; gap: var(--s3); padding-inline: var(--s4); background: color-mix(in srgb, var(--ground) 92%, transparent); border-bottom: 1px solid var(--rule); }\n.hd-brand { font-size: calc(var(--hero) * 0.18); font-weight: 700; line-height: 1.15; color: var(--ink); }\n.js .hd-brand { opacity: 0; }\n.js .hd-bar.is-landed .hd-brand { opacity: 1; }\n.hd-bar nav ul { display: flex; gap: var(--s4); font-size: var(--t-label); color: var(--muted); }\n.shrink-zone { height: 300vh; }\n.shrink-stick { position: sticky; top: 0; height: 100vh; overflow: hidden; }\n.shrink-title {\n  position: absolute;\n  top: 50%;\n  left: var(--s4);\n  margin-top: -0.575em;\n  font-size: var(--hero);\n  font-weight: 700;\n  line-height: 1.15;\n  color: var(--ink);\n  white-space: nowrap;\n  transform-origin: 0 0;\n  transform:\n    translateY(calc(var(--p) * (32px - 50vh + 0.4715em)))\n    scale(calc(1 - var(--p) * 0.82));\n}\n.shrink-lead {\n  position: absolute;\n  left: var(--s4);\n  right: var(--s4);\n  bottom: var(--s5);\n  color: var(--muted);\n  opacity: calc(1 - var(--p) * 2);\n}\n\n@media (prefers-reduced-motion: reduce) {\n  .hd-bar { transition: none; }\n  .shrink-zone { height: auto; }\n  .shrink-stick { position: static; height: auto; padding-block: var(--s7); }\n  .shrink-title, .shrink-lead { display: none; }\n}\n</style>\n</head>\n<body data-motion-number=\"39\">\n<header class=\"dv-label\">\n  <div class=\"dv-wrap\">\n    <p class=\"dv-num\">39</p>\n    <h1 class=\"dv-name\">ヒーロー縮小</h1>\n    <p class=\"dv-ai\">Hero title shrinks into header</p>\n    <p class=\"dv-desc\">大見出しが縮んでヘッダーに収まる</p>\n    <p class=\"dv-hint\">SCROLL ↓</p>\n  </div>\n</header>\n\n<main class=\"dv-stage\">\n  <header class=\"hd-bar\">\n    <p class=\"hd-brand\">見出し</p>\n    <nav aria-label=\"主要メニュー\">\n      <ul>\n        <li>製品</li>\n        <li>事例</li>\n        <li>料金</li>\n      </ul>\n    </nav>\n  </header>\n\n  <div class=\"dv-wrap stack\">\n    <section class=\"dv-card\" data-reveal>\n      <p class=\"dv-eyebrow\">Section 1</p>\n      <h2 class=\"dv-h2\">見出しが入ります</h2>\n      <p class=\"dv-lead\">本文のダミーです。スクロールすると、上の大見出しが縮んでヘッダーへ収まります。</p>\n    </section>\n  </div>\n\n  <section class=\"shrink-zone\" data-progress=\"pin\">\n    <div class=\"shrink-stick\">\n      <p class=\"shrink-title\">見出し</p>\n      <p class=\"shrink-lead\">本文のダミーです。見出しが入ります。</p>\n    </div>\n  </section>\n\n  <div class=\"dv-wrap stack\">\n    <section class=\"dv-card\" data-reveal>\n      <p class=\"dv-eyebrow\">Section 2</p>\n      <h2 class=\"dv-h2\">見出しが入ります</h2>\n      <p class=\"dv-lead\">本文のダミーです。縮み終えた見出しはヘッダーに残ります。</p>\n    </section>\n    <div class=\"dv-ph\" data-reveal></div>\n  </div>\n</main>\n\n<footer class=\"dv-end\">END — 39 ヒーロー縮小</footer>\n\n<script>\n/* dv-motion-helpers:start */\nconst dvReduce = matchMedia('(prefers-reduced-motion: reduce)').matches;\ndocument.documentElement.classList.add('js');\n\n/**\n * 画面に入った要素へ .is-in を付ける。\n * data-reveal=\"repeat\" の要素は画面を出たら外す（何度でも再生）。\n */\nfunction dvReveal(selector = '[data-reveal]', { threshold = 0.2, rootMargin = '0px 0px -8% 0px' } = {}) {\n  const els = [...document.querySelectorAll(selector)];\n  if (dvReduce || !('IntersectionObserver' in window)) {\n    els.forEach((el) => el.classList.add('is-in'));\n    return;\n  }\n  const io = new IntersectionObserver((entries) => {\n    for (const e of entries) {\n      if (e.isIntersecting) {\n        e.target.classList.add('is-in');\n        if (e.target.dataset.reveal !== 'repeat') io.unobserve(e.target);\n      } else if (e.target.dataset.reveal === 'repeat') {\n        e.target.classList.remove('is-in');\n      }\n    }\n  }, { threshold, rootMargin });\n  els.forEach((el) => io.observe(el));\n}\n\n/**\n * スクロール量を 0〜1 にして、各 [data-progress] 要素の CSS 変数 --p に書く。\n *   data-progress=\"through\" : 要素の上端が画面の下端に来たとき 0、下端が画面の上端を抜けたとき 1\n *   data-progress=\"pin\"     : 要素の上端が画面の上端に来たとき 0、下端が画面の下端に来たとき 1\n *                             （中に position: sticky の箱を持つ、背の高い区画用）\n *   data-progress=\"page\"    : ページ全体のスクロール量\n * onUpdate(el, p) を渡すと、値が変わるたびに呼ばれる。\n */\nfunction dvProgress(onUpdate) {\n  const els = [...document.querySelectorAll('[data-progress]')];\n  const clamp = (n) => Math.min(1, Math.max(0, n));\n  let queued = false;\n  const measure = () => {\n    queued = false;\n    const vh = window.innerHeight;\n    for (const el of els) {\n      const r = el.getBoundingClientRect();\n      let p;\n      if (el.dataset.progress === 'pin') p = r.height > vh ? -r.top / (r.height - vh) : 0;\n      else if (el.dataset.progress === 'page') {\n        const max = document.documentElement.scrollHeight - vh;\n        p = max > 0 ? window.scrollY / max : 0;\n      } else p = (vh - r.top) / (vh + r.height);\n      p = clamp(p);\n      el.style.setProperty('--p', p.toFixed(4));\n      if (onUpdate) onUpdate(el, p);\n    }\n  };\n  const request = () => {\n    if (!queued) { queued = true; requestAnimationFrame(measure); }\n  };\n  addEventListener('scroll', request, { passive: true });\n  addEventListener('resize', request);\n  measure();\n}\n/* dv-motion-helpers:end */\n\n/* ---- この演出だけの JS ---- */\nconst hdBar = document.querySelector('.hd-bar');\nif (dvReduce) hdBar.classList.add('is-landed');\ndvReveal();\ndvProgress((el, p) => { if (!dvReduce) hdBar.classList.toggle('is-landed', p >= 0.999); });\n</script>\n</body>\n</html>\n"
    }
  },
  "license": "Original",
  "catalogVersion": 1,
  "designSchemaVersion": 2,
  "capabilities": [
    "live-preview",
    "copy-prompt",
    "get-code"
  ],
  "reusePolicy": "construction-reuse",
  "urls": {
    "ja": "https://design-vault.pages.dev/designs/motion-hero-shrink",
    "en": "https://design-vault.pages.dev/en/designs/motion-hero-shrink",
    "json": "https://design-vault.pages.dev/ai/assets/motion-hero-shrink.json",
    "designJson": null
  }
}