:root {
  --bg: #0B1220;
  --surface: #121B2B;
  --studio: #0E1626;
  --ink: #ECF1F5;
  --ink-2: #A7B4C2;
  --muted: #7F8C9C;
  --line: #22304A;
  --line-2: #2B3B58;
  --teal: #45C2B7;
  --teal-ink: #7FD6CF;
  --teal-soft: #0F2A2A;
  --teal-line: #1F4D4A;
  --amber: #F2B04A;
  --coral: #F08A6B;
  --dark: #05080F;
  --radius: 12px;
  --font: "Zen Kaku Gothic New", "Hiragino Sans", "Noto Sans JP", "Yu Gothic UI", Meiryo, system-ui, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;
  color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
}
a { color: var(--teal-ink); }
button, select, input { font: inherit; color: inherit; }
canvas { display: block; }
.muted { color: var(--ink-2); }
.mono { font-family: var(--mono); font-size: 13px; color: var(--teal); }

/* ---- 上部バー ---- */
.topbar {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; gap: 20px;
  min-height: 60px; padding: 0 max(24px, calc((100vw - 1200px) / 2));
  background: rgba(11, 18, 32, 0.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 700; font-size: 17px; letter-spacing: 0.04em; text-decoration: none; color: var(--ink); white-space: nowrap; }
.brand-mark { width: 28px; height: 28px; border-radius: 6px; background: var(--surface); border: 1px solid var(--line-2); display: inline-flex; align-items: center; justify-content: center; }
.brand-mark svg { width: 16px; height: 16px; }
.progress { flex: 1; display: flex; align-items: center; gap: 16px; min-width: 0; }
.progress-bar { flex: 1; display: flex; gap: 4px; max-width: 420px; }
.progress-bar span { flex: 1; height: 4px; border-radius: 2px; background: var(--line-2); }
.progress-bar span.on { background: var(--teal); }
.progress-count { margin-left: auto; font-family: var(--mono); font-size: 13px; color: var(--ink-2); white-space: nowrap; }
.progress-count.done { color: var(--teal-ink); }
.help-btn {
  display: inline-flex; align-items: center; gap: 6px; min-height: 44px;
  background: none; border: 0; padding: 6px 8px; border-radius: 8px; cursor: pointer; color: var(--ink-2);
}
.help-btn svg { width: 20px; height: 20px; }
.help-btn:hover { background: var(--surface); color: var(--ink); }

/* ---- 本文 ---- */
.main { padding: 44px 24px 72px; max-width: 1248px; width: 100%; margin: 0 auto; }
.eyebrow { margin: 0; font-family: var(--mono); font-size: 13px; letter-spacing: 0.1em; color: var(--teal); }
h1 { font-size: clamp(28px, 3.6vw, 40px); line-height: 1.3; margin: 10px 0 12px; letter-spacing: 0.02em; font-weight: 700; }
.lead { margin: 0 0 20px; color: var(--ink-2); font-size: 17px; max-width: 46em; }
.watch-for { display: flex; align-items: baseline; gap: 14px; margin: 0 0 22px; padding-left: 12px; border-left: 3px solid var(--teal); font-size: 15px; }
.watch-for > span { flex: none; color: var(--teal-ink); font-size: 12px; font-weight: 700; }
.step-heading:focus { outline: none; }

/* ---- 導入 ---- */
.hero { display: flex; flex-wrap: wrap; gap: 48px; align-items: center; padding: 24px 0 40px; }
.hero-text { flex: 1 1 420px; min-width: 0; display: flex; flex-direction: column; gap: 20px; }
.kicker { margin: 0; font-family: var(--mono); font-size: 12.5px; letter-spacing: 0.12em; color: var(--teal); }
.hero-title { font-size: clamp(30px, 3.6vw, 46px); word-break: keep-all; line-height: 1.25; margin: 0; }
.hero .lead { margin: 0; font-size: 18px; max-width: 34em; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 16px; align-items: center; }
.hero-fig { flex: 1 1 560px; min-width: 0; margin: 0; display: flex; flex-direction: column; gap: 10px; }
.hero-fig figcaption { font-size: 13px; color: var(--muted); }
.hero-pano { position: relative; border-radius: 16px; overflow: hidden; border: 1px solid var(--line); background: #000; }
.hero-pano img { display: block; width: 100%; height: auto; }
/* 撮影の途中（左から約3分の2まで写った所）で止めて見せる。動かすと「はじめる」より目立つため（ユーザー判断） */
.hero-mask { position: absolute; inset: 0 0 0 auto; width: 34%; background: rgba(11, 18, 32, 0.82); }
.hero-slit { position: absolute; top: 0; bottom: 0; right: 34%; width: 14px; margin-right: -7px; border-left: 2px solid var(--teal); border-right: 2px solid var(--teal); background: rgba(69, 194, 183, 0.12); }
.route { padding: 24px 0; }
.route-head { display: flex; flex-wrap: wrap; align-items: baseline; gap: 16px; margin-bottom: 20px; }
.route-head h2 { margin: 0; font-size: 24px; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 18px; }
.card { display: flex; flex-direction: column; border-radius: 14px; overflow: hidden; background: var(--surface); border: 1px solid var(--line); text-decoration: none; color: var(--ink); transition: border-color 0.15s, transform 0.15s; }
.card:hover { border-color: var(--teal); transform: translateY(-2px); }
.card-img { display: block; width: 100%; height: 160px; object-fit: cover; }
.card-art { height: 160px; background: var(--studio); display: flex; align-items: center; justify-content: center; }
.card-art svg { width: 200px; height: 120px; }
.card-art.letters { gap: 26px; background: var(--dark); font-family: var(--mono); font-size: 52px; }
.card-art.letters .b { color: var(--amber); transform: scaleX(1.9); filter: blur(3px); opacity: 0.8; }
.card-art.letters .c { color: var(--coral); transform: scaleX(0.55); filter: blur(2px); opacity: 0.85; }
.card-body { padding: 16px 18px 20px; display: flex; flex-direction: column; gap: 6px; }
.card-title { font-size: 18px; font-weight: 700; line-height: 1.5; }
.card-text { font-size: 14px; line-height: 1.7; color: var(--ink-2); }
.features { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 18px; padding: 24px 0 8px; }
.feature { padding: 22px; border-radius: 14px; border: 1px solid var(--line); display: flex; flex-direction: column; gap: 8px; font-size: 14px; line-height: 1.8; }
.feature-title { font-size: 17px; font-weight: 700; }

/* ---- 導入：パノラマの目的 ---- */
.purpose { padding: 8px 0 24px; display: flex; flex-direction: column; gap: 16px; }
.purpose h2 { margin: 0; font-size: 24px; }
.purpose-body { display: flex; flex-wrap: wrap; gap: 24px; align-items: center; }
.purpose-fig { flex: 1 1 560px; min-width: 0; max-width: 100%; height: auto; border-radius: 12px; border: 1px solid var(--line); }
.purpose-text { flex: 1 1 300px; min-width: 0; }
.purpose-text p { margin: 0 0 12px; font-size: 16px; line-height: 1.9; color: var(--ink-2); max-width: 34em; }

/* ---- もっと詳しく ---- */
.more { margin: 28px 0 0; display: flex; flex-direction: column; gap: 10px; max-width: 60em; }
.more-title { margin: 0 0 4px; display: flex; flex-wrap: wrap; align-items: center; gap: 10px; font-size: 17px; }
.more-title svg { width: 18px; height: 18px; color: var(--teal-ink); }
.more-title span { font-size: 13px; font-weight: 400; color: var(--muted); }
.more-item { border-radius: 14px; background: var(--surface); border: 1px solid var(--line); }
.more-item summary { cursor: pointer; min-height: 52px; padding: 13px 20px; font-size: 16px; font-weight: 700; }
.more-body { padding: 0 20px 20px; display: flex; flex-direction: column; gap: 12px; }
.more-body p { margin: 0; font-size: 16px; line-height: 1.9; color: #C9D3DD; max-width: 46em; }
.more-fig { display: block; width: 100%; max-width: 720px; height: auto; border-radius: 10px; border: 1px solid var(--line); }

/* ---- 振り返り ---- */
.recap-cards { margin: 8px 0 0; }
.teaser { display: flex; flex-wrap: wrap; gap: 24px; align-items: center; margin-top: 28px; padding: 22px 24px; border-radius: 16px; border: 1px dashed var(--line-2); }
.teaser img { flex: 1 1 380px; min-width: 0; max-width: 520px; height: auto; border-radius: 12px; }
.teaser > div { flex: 1 1 280px; min-width: 0; display: flex; flex-direction: column; gap: 8px; }
.teaser h2 { margin: 0; font-size: 21px; }
.teaser p { margin: 0; font-size: 15px; }
.tag { align-self: flex-start; padding: 2px 10px; border-radius: 999px; background: #3A3122; color: var(--amber); font-size: 13px; }
.recap-limit { margin: 24px 0 0; max-width: 46em; color: var(--ink-2); font-size: 14px; }

/* ---- 実験エリア ---- */
.stage { display: block; }
.lab { background: var(--surface); border: 1px solid var(--line); border-radius: 14px; padding: 16px; display: grid; gap: 14px; }
.viewport { display: grid; grid-template-columns: minmax(0, 1fr) 190px; gap: 14px; align-items: start; }
.topview-wrap { position: relative; background: var(--studio); border-radius: var(--radius); overflow: hidden; }
.topview { width: 100%; aspect-ratio: 25 / 21; max-height: 64vh; touch-action: none; }
.viewport-note { position: absolute; left: 12px; bottom: 8px; font-size: 14px; color: var(--teal-ink); }
.det-wrap, .frame-wrap, .sky { margin: 0; }
.det-wrap { background: var(--dark); border: 1px solid var(--line); border-radius: var(--radius); padding: 10px; color: #dfe6f0; }
.detector { width: 100%; height: auto; border-radius: 6px; background: var(--dark); }
.det-wrap figcaption, .frame-wrap figcaption, .sky figcaption { display: flex; flex-direction: column; gap: 2px; padding: 8px 2px 0; font-size: 12px; line-height: 1.5; }
.det-wrap figcaption strong { font-size: 14px; color: #fff; }
.det-wrap figcaption span { color: #a9b4c4; }
.viewport-frame { grid-template-columns: minmax(0, 1fr); }
.frame-wrap { background: var(--dark); border: 1px solid var(--line); border-radius: var(--radius); padding: 10px; color: #dfe6f0; max-width: 560px; width: 100%; justify-self: center; }
.frame-canvas { width: 100%; height: auto; aspect-ratio: 3 / 2; border-radius: 6px; background: #000; }
.frame-wrap figcaption { flex-direction: row; gap: 10px; flex-wrap: wrap; }
.frame-wrap figcaption strong { color: #fff; font-size: 14px; }
.frame-wrap figcaption span { color: #a9b4c4; }

.skies { display: grid; gap: 14px; }
.skies-2 { grid-template-columns: 1fr 1fr; }
.sky-canvas { width: 100%; height: auto; border-radius: var(--radius); background: #0b1631; }
.sky figcaption { flex-direction: row; gap: 10px; align-items: baseline; }
.sky figcaption strong { font-size: 15px; }
.sky figcaption span { color: var(--muted); }
.note { margin: 0; font-size: 12.5px; color: var(--muted); }
.loading { margin: 0; color: var(--muted); font-size: 14px; }

/* ---- 操作部品 ---- */
.controls { display: flex; flex-wrap: wrap; gap: 14px 32px; align-items: flex-start; padding: 2px 4px; }
.ctl-slider { flex: 1 1 260px; min-width: 0; max-width: 460px; }
.ctl-head { display: flex; justify-content: space-between; gap: 8px; align-items: baseline; }
.ctl-label { font-size: 14px; font-weight: 700; }
.ctl-head output { font-size: 13.5px; color: var(--teal-ink); font-variant-numeric: tabular-nums; text-align: right; }
.ctl-marks { display: grid; grid-template-columns: 1fr auto 1fr; font-size: 11.5px; color: var(--muted); }
.ctl-marks span:nth-child(2) { text-align: center; }
.ctl-marks span:last-child { text-align: right; }
.ctl-hint { font-size: 12px; color: var(--muted); }
/* スライダーのスナップ先（02章の送りの速さ）。left は値の位置に、つまみの半径（8px）のずれを足して置く */
.snap-ticks { position: relative; height: 15px; margin: -2px 0 2px; }
.snap-tick { position: absolute; top: 0; transform: translateX(-50%); font-size: 11.5px; font-weight: 800; line-height: 1; }
.snap-tick::before { content: ''; display: block; width: 2px; height: 4px; margin: 0 auto 1px; background: currentColor; border-radius: 1px; }
input[type="range"] { width: 100%; accent-color: var(--teal); margin: 6px 0 2px; height: 22px; }
.ctl-seg { display: flex; flex-direction: column; gap: 6px; }
.seg { display: inline-flex; border: 1px solid var(--line-2); border-radius: 9px; padding: 2px; background: var(--studio); }
.seg-btn { border: 0; background: none; padding: 6px 14px; border-radius: 7px; cursor: pointer; font-size: 14px; color: var(--ink-2); }
.seg-btn[aria-pressed="true"] { background: var(--teal); color: var(--bg); font-weight: 700; }
.ctl-toggle { display: inline-flex; align-items: center; gap: 10px; font-size: 14px; cursor: pointer; padding-top: 26px; }
.ctl-toggle input { position: absolute; opacity: 0; pointer-events: none; }
.toggle-ui { width: 38px; height: 22px; border-radius: 99px; background: var(--line-2); position: relative; transition: background 0.15s; flex: none; }
.toggle-ui::after { content: ""; position: absolute; top: 3px; left: 3px; width: 16px; height: 16px; border-radius: 50%; background: #fff; transition: transform 0.15s; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.2); }
.ctl-toggle input:checked + .toggle-ui { background: var(--teal); }
.ctl-toggle input:checked + .toggle-ui::after { transform: translateX(16px); }
.ctl-toggle input:focus-visible + .toggle-ui { outline: 2px solid var(--teal); outline-offset: 2px; }

/* ---- タイムライン ---- */
.timeline { display: flex; flex-wrap: wrap; align-items: center; gap: 10px 12px; padding: 12px; background: var(--studio); border-radius: var(--radius); }
.tl-track { flex: 1 1 120px; display: flex; align-items: center; gap: 10px; min-width: 0; }
.tl-pct { font-size: 14px; color: var(--ink-2); min-width: 3em; text-align: right; font-variant-numeric: tabular-nums; }
.tl-speed select { border: 1px solid var(--line-2); background: var(--surface); border-radius: 8px; padding: 7px 10px; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 7px;
  padding: 8px 14px; border: 1px solid var(--line-2); background: var(--surface);
  border-radius: 9px; cursor: pointer; text-decoration: none; font-size: 14.5px; line-height: 1.4; white-space: nowrap;
}
.btn svg { width: 14px; height: 14px; }
.btn:hover { border-color: var(--ink-2); }
.btn-next:not(.btn-primary) { background: transparent; color: var(--ink); }
.btn-primary { background: var(--teal); color: var(--bg); border-color: var(--teal); font-weight: 700; }
.btn-primary:hover { background: var(--teal-ink); border-color: var(--teal-ink); color: var(--bg); }
.timeline .btn-primary { min-width: 9.5em; }
button:focus-visible, a:focus-visible, select:focus-visible, input:focus-visible, summary:focus-visible { outline: 2px solid var(--teal); outline-offset: 2px; }

/* ---- できあがる像 ---- */
.panos { display: grid; gap: 14px; }
.panos-2 { grid-template-columns: 1fr 1fr; }
.pano { margin: 0; }
.pano figcaption { display: flex; align-items: baseline; gap: 10px; margin-bottom: 6px; }
.pano-label { font-weight: 800; font-size: 15px; }
.pano-sub { font-size: 12.5px; color: var(--muted); }
.pano-status { margin-left: auto; font-size: 12px; color: var(--muted); }
.pano-frame { background: var(--dark); border-radius: 8px; overflow: hidden; border-top: 3px solid var(--line-2); }
.pano.accent-teal .pano-frame { border-top-color: var(--teal); }
.pano.accent-coral .pano-frame { border-top-color: var(--coral); }
.pano-canvas { width: 100%; height: auto; }

.legend { list-style: none; display: flex; flex-wrap: wrap; gap: 6px 20px; padding: 10px 4px 0; margin: 0; font-size: 13.5px; color: var(--ink-2); }
.legend li { display: inline-flex; align-items: center; gap: 6px; }
.legend .dot { width: 11px; height: 11px; border-radius: 50%; display: inline-block; }
.legend b { color: var(--ink); }
.legend-note { color: var(--muted); font-size: 12.5px; }

.chips { list-style: none; display: flex; flex-wrap: wrap; gap: 8px; margin: 10px 0 0; padding: 0; }
.chips li { padding: 4px 10px; border-radius: 6px; background: #1E2A42; font-size: 14px; }
.chips li.sharp { background: #163A3A; color: var(--teal-ink); }
.pano-frame { position: relative; }
.callout { position: absolute; padding: 5px 10px; border-radius: 6px; background: rgba(11, 18, 32, 0.85); border: 1px solid var(--teal); font-size: 13px; line-height: 1.4; white-space: nowrap; pointer-events: none; }
.callout-amber { border-color: var(--amber); }
.callout[hidden] { display: none; }
/* 吹き出しの向き（up：上、down：下、left：左、right：右の構造を指す） */
.callout-up::before, .callout-down::before, .callout-left::before, .callout-right::before { content: ''; position: absolute; border: 6px solid transparent; }
.callout-down::before { top: 100%; left: 14px; border-top-color: var(--teal); }
.callout-up::before { bottom: 100%; left: 14px; border-bottom-color: var(--teal); }
.callout-left::before { right: 100%; top: 50%; margin-top: -6px; border-right-color: var(--teal); }
.callout-right::before { left: 100%; top: 50%; margin-top: -6px; border-left-color: var(--teal); }
.callout-amber.callout-up::before { border-bottom-color: var(--amber); }
.callout-amber.callout-left::before { border-right-color: var(--amber); }
.callout-amber.callout-right::before { border-left-color: var(--amber); }
.callout-amber.callout-down::before { border-top-color: var(--amber); }
@media (max-width: 600px) { .callout { font-size: 11px; padding: 3px 7px; } }

/* ---- 3D表示（03・04） ---- */
.viewport-3d { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); }
.top-wrap { margin: 0; background: var(--studio); border-radius: var(--radius); padding: 0 0 8px; overflow: hidden; }
.topview-gpu { width: 100%; aspect-ratio: 4 / 3; display: block; }
.top-wrap figcaption { padding: 4px 10px 0 !important; }
.det-row { display: grid; grid-template-columns: minmax(0, 360px) 1fr; gap: 14px; align-items: center; }
.det-row figcaption { padding: 0 !important; }
.top-wrap figcaption { display: flex; flex-direction: column; gap: 2px; padding: 6px 2px 0; font-size: 12px; line-height: 1.5; }
.top-wrap figcaption strong { font-size: 14px; }
.top-wrap figcaption span { color: var(--muted); }
.view3d-wrap { position: relative; border-radius: var(--radius); overflow: hidden; background: var(--studio); }
.view3d { width: 100%; aspect-ratio: 4 / 3; max-height: 62vh; touch-action: none; cursor: grab; }
.view3d:active { cursor: grabbing; }
.instant { width: 100%; aspect-ratio: 3 / 2; border-radius: 6px; background: var(--dark); }
.legend-3d { padding-top: 0; }
.pos-readout { list-style: none; margin: 4px 0 0; padding: 0; font-size: 13.5px; display: grid; gap: 2px; }
.pos-readout li { display: flex; align-items: center; gap: 6px; }
.pos-readout .dot { width: 10px; height: 10px; border-radius: 50%; display: inline-block; }
.ctl-actions { display: flex; align-items: flex-end; padding-top: 22px; }

/* ---- 観察のポイントと解説 ---- */
.point { margin: 32px 0 14px; padding: 26px 30px; border: 1px solid var(--teal-line); background: var(--teal-soft); border-radius: 16px; }
.point h2 { margin: 0 0 8px; font-family: var(--mono); font-weight: 500; font-size: 13px; color: var(--teal-ink); letter-spacing: 0.1em; }
.point p { margin: 0; font-size: clamp(18px, 2vw, 22px); font-weight: 700; line-height: 1.6; max-width: 40em; }
/* ---- 問いと解説 ---- */
.question { margin: 28px 0 10px; }
.question p { margin: 0; font-size: clamp(18px, 2.2vw, 23px); font-weight: 700; line-height: 1.55; letter-spacing: 0.01em; }
.explain { border: 1px solid var(--line); border-radius: 14px; background: var(--surface); padding: 0 20px; max-width: 60em; }
.explain summary { cursor: pointer; padding: 12px 0; color: var(--teal-ink); font-weight: 700; font-size: 15px; }
.explain p { margin: 0 0 14px; color: var(--ink-2); }
.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 40px; flex-wrap: wrap; }
.btn-next { min-height: 48px; padding: 12px 22px; font-size: 16px; white-space: normal; text-align: left; }
.btn-next svg { width: 16px; height: 16px; }
.done { color: var(--muted); align-self: center; }
.chapter-bridge { margin: 28px 0 0; padding-top: 20px; border-top: 1px solid var(--line); color: var(--ink-2); max-width: 52em; }
.chapter-bridge > span { display: block; margin-bottom: 4px; color: var(--teal-ink); font-size: 12px; font-weight: 700; }
.course-recap { margin-top: 32px; padding-top: 24px; border-top: 1px solid var(--line-2); }
.course-recap h2 { margin: 4px 0 8px; font-size: 24px; line-height: 1.5; }
.course-recap > p { margin: 0; }
.course-recap ol { list-style: none; padding: 0; margin: 18px 0; display: grid; grid-template-columns: 1fr 1fr; gap: 0 28px; }
.course-recap li { padding: 14px 0; border-bottom: 1px solid var(--line); }
.course-recap li a { display: inline-flex; gap: 12px; min-height: 44px; align-items: center; color: var(--teal-ink); font-weight: 700; text-underline-offset: 4px; }
.recap-num { font-size: 12px; font-variant-numeric: tabular-nums; }
.course-recap li p { margin: 0; color: var(--ink-2); font-size: 14px; }
.recap-limit { max-width: 46em; color: var(--ink-2); font-size: 14px; }

dialog { border: 1px solid var(--line); border-radius: 14px; padding: 20px 24px; max-width: min(520px, calc(100vw - 32px)); color: var(--ink); background: var(--surface); }
dialog::backdrop { background: rgba(0, 0, 0, 0.55); }
dialog h2 { margin: 0 0 8px; font-size: 20px; }
dialog ul { padding-left: 1.2em; color: var(--ink-2); font-size: 15px; }
.help-actions { display: flex; flex-wrap: wrap; gap: 10px; }

/* ---- スマホ・タブレット ---- */
@media (max-width: 1100px) {
  .panos-2 { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 900px) {
  .main { padding: 28px 16px 48px; }
  .topbar { padding: 0 16px; gap: 12px; }
  .progress-bar { display: none; }
  .help-btn span, .help-btn { font-size: 0; }
  .help-btn svg { width: 22px; height: 22px; }
}
@media (max-width: 760px) {
  .viewport { grid-template-columns: minmax(0, 1fr); }
  .det-wrap { display: grid; grid-template-columns: 110px 1fr; gap: 12px; align-items: center; }
  .viewport-3d { grid-template-columns: minmax(0, 1fr); }
  .viewport-3d .det-wrap { grid-template-columns: 160px 1fr; }
  .det-row { grid-template-columns: 150px 1fr; }
  .view3d { aspect-ratio: 1 / 1; max-height: none; }
  .det-wrap figcaption { padding: 0; }
  .panos-2, .skies-2 { grid-template-columns: minmax(0, 1fr); }
  .lab { padding: 10px; border-radius: 12px; }
  .topview { aspect-ratio: 25 / 23; max-height: none; }
  .timeline { padding: 10px; }
  .timeline .tl-track { order: -1; flex-basis: 100%; }
  .timeline .btn span { font-size: 13.5px; }
  .ctl-slider { flex-basis: 100%; max-width: none; }
  .ctl-toggle { padding-top: 4px; }
  .eyebrow-row { flex-wrap: wrap; gap: 4px 16px; margin-bottom: 6px; }
  .watch-for { display: block; font-size: 14px; }
  .watch-for > span { display: block; margin-bottom: 2px; }
  .point { padding: 20px; }
  .hero { gap: 28px; padding-top: 4px; }
  .card-img, .card-art { height: 130px; }
}

/* UX: 比較する像と、その像を変える操作を一つの領域に置く。 */
[hidden] { display: none !important; }
.chapter-picker { display: flex; align-items: center; gap: 8px; min-width: 0; font-size: 13px; }
.chapter-picker select { max-width: 220px; width: 100%; min-width: 0; }
select { background: var(--surface); border: 1px solid var(--line-2); border-radius: 8px; padding: 8px; }
.lab-compare { grid-template-columns: minmax(230px, 0.7fr) minmax(0, 2fr); align-items: start; }
.lab-compare > .controls { display: block; padding: 0; }
.pose-panel, .topic-panel { min-width: 0; width: 100%; margin: 0; border: 0; padding: 0; display: grid; gap: 10px; }
.pose-panel legend, .topic-panel legend { font-weight: 700; margin-bottom: 10px; }
.pose-panel .ctl-slider, .topic-panel .ctl-slider { max-width: none; width: 100%; }
.pose-panel .btn { justify-self: start; }
.pose-readout { margin: 0; font-size: 12px; color: var(--ink-2); }
.topic-controls { display: grid; gap: 10px; }
.topic-panel .ctl-toggle { padding-top: 0; min-height: 36px; }
.topic-panel .explain { margin: 0; }
.topic-panel p { margin: 0; }
.result-area { min-width: 0; }
.lab-compare .panos-2 { grid-template-columns: 1fr 1fr; }
.lab-compare .pano figcaption { display: block; }
.lab-compare .pano-sub { display: block; }
.lab-compare .pano-canvas { min-height: 0; }
.apparatus-details, .playback-details { grid-column: 1 / -1; border-top: 1px solid var(--line); padding-top: 10px; min-width: 0; }
.apparatus-details summary, .playback-details summary { cursor: pointer; font-weight: 700; }
.apparatus-body { display: grid; gap: 12px; margin-top: 12px; }
.apparatus-body .view3d { max-height: 340px; }
.apparatus-body .topview-gpu { max-height: 340px; }
.model-limit { padding: 14px 18px; margin-bottom: 14px; background: #302719; border: 1px solid #665138; border-radius: 10px; font-size: 14px; }
.model-limit p { margin: 6px 0; }
.cervical-explanation { margin: 24px 0; display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 20px; align-items: center; scroll-margin-top: 90px; }
.cervical-explanation img { width: 100%; border-radius: 10px; }
.cervical-explanation p { margin: 8px 0; }
.lab-letters .topview { max-height: 380px; }
.lab-letters .viewport { max-width: 760px; width: 100%; justify-self: center; }
.lab-letters .pano { max-width: 820px; width: 100%; justify-self: center; }
.stars-supplement .lab { margin-top: 14px; }
@media (max-width: 760px) {
  .topbar { flex-wrap: wrap; padding: 8px 16px; gap: 6px 12px; }
  .topbar .brand { font-size: 13px; }
  .chapter-picker { flex: 1 1 110px; }
  .chapter-picker > span { position: absolute; width: 1px; height: 1px; overflow: hidden; clip-path: inset(50%); }
  .chapter-picker select { max-width: none; height: 36px; font-size: 12px; }
  .progress-count { font-size: 12px; white-space: nowrap; }
  .lab-compare { grid-template-columns: minmax(0, 1fr); gap: 10px; }
  .lab-compare .panos-2 { grid-template-columns: minmax(0, 1fr); gap: 8px; }
  .lab-compare .pano figcaption { display: flex; flex-wrap: wrap; gap: 4px 8px; font-size: 13px; margin-bottom: 2px; }
  .lab-compare .pano-label { font-size: 13px; }
  .lab-compare .pano-sub { font-size: 11px; }
  .pose-panel, .topic-panel { gap: 6px; }
  .pose-panel legend, .topic-panel legend { margin-bottom: 4px; }
  .pose-panel .ctl-slider { flex-basis: auto; }
  .pose-panel .btn { min-height: 36px; padding: 4px 10px; }
  .pose-readout { line-height: 1.5; }
  .cervical-explanation { grid-template-columns: minmax(0, 1fr); }
  .lab-letters .topview { max-height: 280px; }
  .lab-letters .viewport-note { font-size: 11px; }
  .lab-letters .ctl-hint { display: none; }
  .lab-letters .controls { gap: 8px 16px; }
}
@media (max-width: 760px) {
  /* 章選択を別行にして、進捗の数字を押しつぶさない。 */
  .chapter-picker { order: 4; flex: 1 1 100%; }
  .topbar .progress { flex: 1; }
}

/* 実写から文字の実験へつなぐ比較 */

/* 姿勢操作の直上に、撮影装置で隠れない頭蓋骨を表示する。 */
.pose-model { margin: 0 0 14px; min-width: 0; }
.pose-model figcaption { font-weight: 700; margin-bottom: 6px; }
.pose-model .view3d { display: block; height: 230px; aspect-ratio: auto; max-height: none; }
.pose-model .note { margin: 6px 0 0; font-size: 11px; }
.pose-model .legend-ref { padding: 6px 0 0; gap: 2px 12px; font-size: 12px; }
@media (max-width: 760px) { .pose-model .view3d { height: 190px; } }

.lab-pose-model .viewport-3d { grid-template-columns: minmax(0, 1fr); }

/* 歯列：装置と生成像を同じ観察面に置く。再生は折りたたまない。 */
.lab-observe .observation-pair { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 16px; align-items: center; }
.observation-apparatus { min-width: 0; }
.observation-apparatus h2 { font-size: 14px; margin: 0 0 8px; }
.lab-observe .viewport-3d { grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 8px; }
.lab-observe .view3d, .lab-observe .topview-gpu { width: 100%; height: 210px; aspect-ratio: auto; }
.lab-observe .top-wrap figcaption span { display: none; }
.lab-observe .viewport-note { font-size: 10px; }
.lab-observe > .controls { border-top: 1px solid var(--line); padding-top: 12px; }
.lab-observe .topic-panel { grid-template-columns: minmax(160px, 240px) minmax(0, 1fr); }
.lab-observe .topic-panel > label { grid-column: 1 / -1; }
.lab-observe .topic-controls { grid-column: 1 / -1; }
.detector-details { min-width: 0; border-top: 1px solid var(--line); padding-top: 10px; }
.detector-details summary { cursor: pointer; }
.detector-details .det-row { margin-top: 12px; }
@media (max-width: 800px) {
  .lab-observe .observation-pair { grid-template-columns: minmax(0, 1fr); gap: 8px; }
  .lab-observe .view3d, .lab-observe .topview-gpu { height: 145px; }
  .lab-observe .topic-panel { grid-template-columns: minmax(0, 1fr); }
  .lab-observe .pano { margin: 0; }
}

.playback-options { border-top: 1px solid var(--line); padding-top: 10px; min-width: 0; }
.playback-options summary { cursor: pointer; }
.playback-options .timeline { margin-top: 10px; }


/* 操作と結果を近づける。補助設定は観察枠の後に置く。 */
.letter-options { border-top: 1px solid var(--line); padding-top: 10px; min-width: 0; }
.letter-options summary { cursor: pointer; min-height: 36px; }
.letter-options > .controls, .letter-options > .timeline, .letter-options > p { margin-top: 12px; }
.letter-options .ctl-toggle { padding-top: 0; }
/* 上にそろえる：右の列（送り・再生・フィルム）の高さが像の到着で変わっても、上から見た図が動かないように */
.feed-experiment { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.2fr); gap: 16px; align-items: start; }
.feed-controls { display: grid; gap: 10px; min-width: 0; }
.feed-controls .ctl-slider { max-width: none; }
.lab-feed .viewport { grid-template-columns: minmax(0, 1fr) 130px; gap: 8px; }
.lab-feed .topview { display: block; height: 300px; max-height: none; aspect-ratio: auto; }
.lab-feed .viewport-note { font-size: 11px; }
.lab-feed .det-wrap { display: block; padding: 6px; }
.lab-feed .det-wrap figcaption { padding-top: 4px; }
.lab-feed .pano { margin: 0; }
.lab-feed .ctl-hint { display: block; }
.apparatus-switch { display: none; }
@media (max-width: 800px) {
  .feed-experiment { grid-template-columns: minmax(0, 1fr); gap: 10px; }
  .lab-feed .viewport { grid-template-columns: minmax(0, 1fr) 110px; }
  .lab-feed .topview { height: 220px; }
  .lab-feed .timeline { flex-wrap: nowrap; padding: 8px; gap: 8px; }
  .lab-feed .timeline .tl-track { order: 0; flex: 1; min-width: 0; }
  .lab-feed .timeline .btn-primary { min-width: 0; padding: 8px; }
  .lab-feed .ctl-head { flex-wrap: wrap; gap: 0 8px; }
  .apparatus-switch { display: flex; gap: 8px; margin-bottom: 8px; }
  .apparatus-switch .btn { min-height: 44px; }
  .apparatus-switch [aria-pressed="true"] { background: var(--teal); color: var(--bg); }
  .lab-observe .viewport-3d { grid-template-columns: minmax(0, 1fr); }
  .lab-observe .view3d, .lab-observe .topview-gpu { height: 220px; }
  .observation-apparatus[data-view="3d"] .top-wrap,
  .observation-apparatus[data-view="top"] .view3d-wrap { display: none; }
}

/* 01章：フィルムを上から見た図の横に置く（操作しながら像の変化を見る）。狭い画面では図の真下 */
.lab-film-beside .viewport { max-width: none; grid-template-columns: minmax(0, 1fr) minmax(0, 1.1fr); align-items: start; }
.lab-film-beside .film-side { display: grid; gap: 10px; min-width: 0; }
.lab-film-beside .pano { max-width: none; }
.lab-film-beside .det-wrap { display: grid; grid-template-columns: 150px 1fr; gap: 12px; align-items: center; padding: 8px; }
.lab-film-beside .det-wrap figcaption { padding: 0; }
.lab-film-beside .topview { max-height: 420px; }
@media (max-width: 760px) {
  .lab-film-beside .viewport { grid-template-columns: minmax(0, 1fr); gap: 8px; }
  .lab-film-beside .det-wrap { grid-template-columns: 110px 1fr; }
  .lab-film-beside .topview { max-height: 260px; }
}
/* 導入の3コマの帯（ポップ）：照らす → 重なる → 広げる */
.story { margin: 8px 0 40px; }
.story-strip { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 22px; counter-reset: none; }
.story-card { position: relative; display: flex; flex-direction: column; gap: 6px; padding: 14px 14px 16px; border-radius: 18px; background: var(--surface); border: 2px solid var(--tone); box-shadow: 6px 6px 0 var(--tone); transform: rotate(var(--tilt, 0deg)); transition: transform .2s ease; }
.story-card:hover { transform: rotate(0deg) translateY(-3px); }
.story-card:nth-child(1) { --tilt: -1.2deg; }
.story-card:nth-child(2) { --tilt: .8deg; }
.story-card:nth-child(3) { --tilt: -.6deg; }
.story-card.tone-teal { --tone: var(--teal); }
.story-card.tone-coral { --tone: var(--coral); }
.story-card.tone-amber { --tone: var(--amber); }
.story-card img { width: 100%; height: 150px; object-fit: contain; background: #0b0f17; border-radius: 12px; }
.story-card strong { font-size: 18px; color: #fff; letter-spacing: .02em; }
.story-card > span:last-child { font-size: 13px; color: var(--muted); line-height: 1.6; }
.story-num { position: absolute; top: -14px; left: -10px; width: 40px; height: 40px; border-radius: 50%; display: grid; place-items: center; background: var(--tone); color: #0E1626; font: 800 15px var(--mono); box-shadow: 0 3px 0 rgba(0,0,0,.35); }
.story-card:not(:last-child)::after { content: '→'; position: absolute; right: -20px; top: 50%; transform: translateY(-50%); color: var(--tone); font-size: 22px; font-weight: 800; }
.story-next { display: flex; align-items: center; justify-content: center; gap: 16px; flex-wrap: wrap; margin-top: 26px; }
.story-next p { margin: 0; font-size: 16px; font-weight: 700; }
@media (prefers-reduced-motion: reduce) { .story-card { transform: none; transition: none; } }
@media (max-width: 760px) {
  .story-strip { grid-template-columns: minmax(0, 1fr); gap: 22px; padding: 0 6px; }
  .story-card { display: grid; grid-template-columns: 112px minmax(0, 1fr); grid-template-rows: auto 1fr; column-gap: 12px; row-gap: 4px; padding: 10px 12px; align-items: start; }
  .story-card img { grid-row: 1 / 3; height: 84px; }
  .story-card strong { font-size: 16px; align-self: end; }
  .story-num { width: 32px; height: 32px; font-size: 13px; top: -12px; left: -8px; }
  .story-card:not(:last-child)::after { content: '↓'; right: auto; left: 50%; top: auto; bottom: -27px; transform: translateX(-50%); }
}
/* スマホ：切り替えと折りたたみの見出しを、指で押しやすい高さ（40px 以上）にする */
@media (max-width: 760px) {
  .ctl-toggle { min-height: 40px; }
  details > summary { padding-block: 8px; }
}

/* 02章の補足（舌・ピアス）の講義資料の図 */
.topic-fig { margin: 4px 0 12px; }
.topic-fig figcaption { margin-top: 6px; }

/* 導線：手順を開いたときに最初に触る所を囲む（guide.js）。触ったら消える */
.guide { position: absolute; z-index: 5; pointer-events: none; border: 2px solid var(--teal); border-radius: 12px; box-shadow: 0 0 0 4px rgba(69, 194, 183, 0.18); animation: guide-pulse 2.4s ease-in-out infinite; }
.guide[hidden] { display: none; }
.guide-label { position: absolute; left: 8px; bottom: calc(100% + 6px); padding: 1px 10px; border-radius: 999px; background: var(--teal); color: var(--bg); font-size: 13px; font-weight: 700; line-height: 1.7; white-space: nowrap; box-shadow: 0 2px 10px rgba(0, 0, 0, 0.35); }
.guide.below .guide-label { bottom: auto; top: calc(100% + 6px); }
.guide.at-right .guide-label { left: calc(100% + 8px); bottom: auto; top: 6px; }
@keyframes guide-pulse { 50% { border-color: rgba(69, 194, 183, 0.55); box-shadow: 0 0 0 8px rgba(69, 194, 183, 0.05); } }
/* 主な操作が済んだら、画面の下に「次へ」を出す（ページの「次へ」が見えているあいだは隠す。自動では進まない） */
.next-bar { position: fixed; left: 0; right: 0; bottom: 0; z-index: 15; display: flex; justify-content: center; padding: 28px 16px calc(14px + env(safe-area-inset-bottom)); background: linear-gradient(to top, rgba(11, 18, 32, 0.96) 50%, rgba(11, 18, 32, 0)); pointer-events: none; animation: next-bar-in 0.35s ease-out; }
.next-bar .btn { pointer-events: auto; max-width: 100%; white-space: normal; text-align: center; padding: 11px 20px; font-size: 15.5px; box-shadow: 0 6px 22px rgba(0, 0, 0, 0.5), 0 0 0 4px rgba(69, 194, 183, 0.18); }
@keyframes next-bar-in { from { transform: translateY(100%); opacity: 0; } }
@media (prefers-reduced-motion: reduce) { .guide, .next-bar { animation: none; } }

/* デモの指（demo.js）。指先が座標に来るように置く。押しているあいだは指先に輪を出す */
.demo-finger { position: fixed; left: 0; top: 0; z-index: 20; width: 36px; height: 36px; margin: -4px 0 0 -16px; pointer-events: none; isolation: isolate; filter: drop-shadow(0 3px 6px rgba(0, 0, 0, 0.45)); }
.demo-finger[hidden] { display: none; }
.demo-finger svg { display: block; width: 100%; height: 100%; }
.demo-finger::before { content: ''; position: absolute; left: 2px; top: -10px; width: 28px; height: 28px; border-radius: 50%; z-index: -1; background: rgba(69, 194, 183, 0.3); border: 2px solid rgba(69, 194, 183, 0.85); opacity: 0; transform: scale(0.5); transition: opacity 0.15s, transform 0.15s; }
.demo-finger.press::before { opacity: 1; transform: none; }