:root {
  color-scheme: light dark;
  --bg: #f2f5f7;
  --surface: #ffffff;
  --surface-2: #e8eef1;
  --ink: #172126;
  --muted: #586870;
  --line: #c8d4d9;
  --graphite: #18272d;
  --beam: #19b9c5;
  --beam-soft: #d7f5f7;
  --se: #3fa66c;
  --bse: #e29a32;
  --xray: #c74f86;
  --danger: #c94b45;
  --focus: #006f7a;
  --shadow: 0 18px 45px rgba(21, 39, 46, .12);
  --radius: 18px;
  --radius-lg: 28px;
  --mono: "Cascadia Mono", "Segoe UI Mono", Consolas, monospace;
  --max: 1180px;
}

:root[data-theme="dark"] {
  --bg: #0d1519;
  --surface: #142127;
  --surface-2: #1b2d34;
  --ink: #edf6f7;
  --muted: #afc2c8;
  --line: #35505a;
  --graphite: #071014;
  --beam-soft: #113f43;
  --focus: #74e5ed;
  --shadow: 0 18px 45px rgba(0, 0, 0, .35);
}

@media (prefers-color-scheme: dark) {
  :root[data-theme="auto"] {
    --bg: #0d1519;
    --surface: #142127;
    --surface-2: #1b2d34;
    --ink: #edf6f7;
    --muted: #afc2c8;
    --line: #35505a;
    --graphite: #071014;
    --beam-soft: #113f43;
    --focus: #74e5ed;
    --shadow: 0 18px 45px rgba(0, 0, 0, .35);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-width: 320px;
  background: var(--bg);
  color: var(--ink);
  font-family: "Segoe UI Variable", "Microsoft JhengHei", "Noto Sans TC", system-ui, sans-serif;
  line-height: 1.65;
}
button, input, select { font: inherit; }
button, select, input[type="range"] { min-height: 44px; }
button { cursor: pointer; }
a { color: var(--focus); }
img, canvas { max-width: 100%; }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; }

.skip-link {
  position: fixed; left: 1rem; top: -5rem; z-index: 1000;
  padding: .7rem 1rem; border-radius: 8px; background: var(--surface); color: var(--ink);
}
.skip-link:focus { top: 1rem; }

.site-header {
  position: sticky; top: 0; z-index: 50;
  color: #fff; background: rgba(14, 28, 34, .96);
  border-bottom: 1px solid rgba(255,255,255,.15);
  backdrop-filter: blur(12px);
}
.header-inner {
  width: min(var(--max), calc(100% - 2rem)); margin: auto;
  min-height: 70px; display: flex; align-items: center; gap: 1rem;
}
.brand { display: flex; align-items: center; gap: .8rem; color: #fff; text-decoration: none; }
.brand-mark {
  width: 38px; height: 38px; border-radius: 50%; position: relative;
  border: 2px solid var(--beam); box-shadow: 0 0 20px rgba(25,185,197,.45);
}
.brand-mark::before, .brand-mark::after { content: ""; position: absolute; background: var(--beam); }
.brand-mark::before { width: 2px; height: 48px; left: 17px; top: -7px; transform: rotate(35deg); }
.brand-mark::after { width: 8px; height: 8px; border-radius: 50%; right: 3px; bottom: 4px; }
.brand-copy { display: grid; line-height: 1.15; }
.brand-copy strong { font-size: .95rem; letter-spacing: .03em; }
.brand-copy small { color: #a8c3ca; font-size: .72rem; }
.header-actions { margin-left: auto; display: flex; gap: .45rem; }
.icon-btn {
  border: 1px solid rgba(255,255,255,.25); border-radius: 999px; padding: .45rem .75rem;
  background: rgba(255,255,255,.08); color: #fff;
}
.icon-btn:hover { background: rgba(255,255,255,.16); }
.site-back {
  flex: none; display: inline-flex; align-items: center; gap: .3rem;
  border: 1px solid rgba(255,255,255,.25); border-radius: 999px;
  padding: .42rem .75rem; font-size: .78rem; font-weight: 600; letter-spacing: .02em;
  background: rgba(255,255,255,.08); color: #fff; text-decoration: none;
  transition: background .2s, border-color .2s;
}
.site-back:hover { background: rgba(255,255,255,.18); border-color: rgba(255,255,255,.5); }

.course-rail {
  background: var(--surface); border-bottom: 1px solid var(--line); overflow-x: auto;
  scrollbar-width: thin;
}
.rail-inner {
  width: min(var(--max), calc(100% - 2rem)); margin: auto; padding: .55rem 0;
  display: flex; min-width: max-content; align-items: center; gap: .35rem;
}
.rail-link {
  display: inline-flex; align-items: center; gap: .35rem; min-height: 36px; padding: .35rem .65rem;
  border-radius: 999px; color: var(--muted); text-decoration: none; font-size: .78rem;
  border: 1px solid transparent;
}
.rail-link::before { content: attr(data-no); display: grid; place-items: center; width: 22px; height: 22px; border-radius: 50%; background: var(--surface-2); font-weight: 800; }
.rail-link.active { color: var(--ink); border-color: var(--beam); background: var(--beam-soft); }
.rail-link.done::before { content: "✓"; color: #fff; background: var(--se); }

main { width: min(var(--max), calc(100% - 2rem)); margin: auto; padding: 2rem 0 5rem; }
.hero {
  position: relative; overflow: hidden; border-radius: 28px; padding: clamp(2rem, 5vw, 4.6rem);
  color: #fff; background:
    radial-gradient(circle at 82% 18%, rgba(25,185,197,.32), transparent 30%),
    linear-gradient(135deg, #17292f, #0b171c 70%);
  box-shadow: var(--shadow);
}
.hero::after {
  content: ""; position: absolute; inset: auto -10% -50% 42%; height: 260px;
  border: 1px solid rgba(25,185,197,.5); border-radius: 50%; transform: rotate(-12deg);
  box-shadow: 0 0 0 28px rgba(25,185,197,.05), 0 0 0 58px rgba(25,185,197,.03);
}
.hero > * { position: relative; z-index: 1; }
.eyebrow { margin: 0 0 .5rem; color: #79dbe1; font-size: .8rem; font-weight: 800; letter-spacing: .13em; text-transform: uppercase; }
.hero h1 { margin: 0; max-width: 850px; font-size: clamp(2rem, 5vw, 4.4rem); line-height: 1.05; letter-spacing: -.04em; }
.hero .en { margin: .7rem 0 0; color: #a8c3ca; font-family: Georgia, serif; font-size: clamp(1rem, 2.2vw, 1.5rem); }
.hero .lead { max-width: 760px; margin: 1.35rem 0 0; color: #dcebed; font-size: clamp(1rem, 1.8vw, 1.2rem); }
.hero-actions { display: flex; flex-wrap: wrap; gap: .7rem; margin-top: 1.5rem; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: .45rem;
  border: 1px solid var(--line); border-radius: 12px; padding: .65rem 1rem;
  background: var(--surface); color: var(--ink); text-decoration: none; font-weight: 750;
}
.btn:hover { transform: translateY(-1px); box-shadow: 0 8px 18px rgba(0,0,0,.1); }
.btn.primary { border-color: var(--beam); background: var(--beam); color: #062329; }
.btn.ghost { background: transparent; color: inherit; }
.hero .btn.ghost { border-color: rgba(255,255,255,.3); color: #fff; }
.btn.danger { border-color: var(--danger); color: var(--danger); }
.btn.small { min-height: 36px; padding: .35rem .65rem; font-size: .78rem; }

.mission-grid, .dashboard-grid, .chapter-grid { display: grid; gap: 1rem; margin-top: 1.4rem; }
.mission-grid { grid-template-columns: 1.3fr .7fr; }
.dashboard-grid { grid-template-columns: repeat(3, 1fr); }
.chapter-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.panel, .chapter-card, .lab-card, .quiz-panel, .evidence-card {
  background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius); box-shadow: 0 8px 24px rgba(24,39,45,.06);
}
.panel { padding: 1.25rem; }
.panel h2, .panel h3 { margin-top: 0; }
.metric { font-size: 2rem; font-weight: 900; line-height: 1; }
.metric-label { margin-top: .35rem; color: var(--muted); font-size: .82rem; }
.progress-track { height: 10px; background: var(--surface-2); border-radius: 99px; overflow: hidden; }
.progress-fill { width: 0; height: 100%; background: linear-gradient(90deg, var(--beam), var(--se)); transition: width .35s; }

.chapter-card { display: grid; grid-template-columns: 56px 1fr auto; align-items: center; gap: 1rem; padding: 1.15rem; text-decoration: none; color: var(--ink); }
.chapter-card:hover { border-color: var(--beam); transform: translateY(-2px); box-shadow: var(--shadow); }
.chapter-no { width: 54px; height: 54px; border-radius: 16px; display: grid; place-items: center; background: var(--graphite); color: #fff; font-size: 1.2rem; font-weight: 900; }
.chapter-card.done .chapter-no { background: var(--se); }
.chapter-copy strong { display: block; font-size: 1.05rem; }
.chapter-copy small { color: var(--muted); }
.chapter-status { color: var(--muted); font-size: .78rem; text-align: right; }

.section-block { margin-top: 2rem; scroll-margin-top: 130px; }
.section-head { display: flex; gap: 1rem; align-items: end; justify-content: space-between; margin-bottom: .85rem; }
.section-kicker { margin: 0; color: var(--focus); font-size: .75rem; letter-spacing: .1em; font-weight: 900; text-transform: uppercase; }
.section-head h2 { margin: .1rem 0 0; font-size: clamp(1.45rem, 3vw, 2.15rem); line-height: 1.2; }
.concept-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: .8rem; }
.concept {
  padding: 1rem; border-radius: 14px; background: var(--surface); border-left: 4px solid var(--beam);
  box-shadow: 0 6px 18px rgba(24,39,45,.06);
}
.concept strong { display: block; margin-bottom: .25rem; }
.concept p { margin: 0; color: var(--muted); font-size: .9rem; }

.source-badge {
  display: inline-flex; align-items: center; min-height: 30px; padding: .25rem .65rem;
  border: 1px solid var(--line); border-radius: 999px; color: var(--muted);
  background: var(--surface); font-size: .72rem; font-weight: 850;
}
.gallery-intro { margin: -.25rem 0 1rem; color: var(--muted); font-size: .88rem; }
.slide-gallery { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 1rem; }
.slide-figure {
  min-height: 0; padding: 0; overflow: hidden; text-align: left;
  border: 1px solid var(--line); border-radius: 15px; background: var(--surface); color: var(--ink);
  box-shadow: 0 7px 20px rgba(24,39,45,.07); transition: transform .18s, border-color .18s, box-shadow .18s;
}
.slide-figure:hover { transform: translateY(-3px); border-color: var(--beam); box-shadow: var(--shadow); }
.slide-image-wrap { display: grid; place-items: center; height: 210px; padding: .45rem; background: #eef2f3; }
.slide-image-wrap img { width: 100%; height: 100%; object-fit: contain; }
.slide-caption { display: block; padding: .75rem .85rem .9rem; color: var(--muted); font-size: .82rem; }
.slide-caption b { display: block; margin-bottom: .2rem; color: var(--focus); font-size: .72rem; letter-spacing: .04em; }
.image-dialog {
  width: min(1120px, calc(100% - 2rem)); max-height: calc(100vh - 2rem); padding: 0;
  border: 1px solid var(--line); border-radius: 18px; background: var(--surface); color: var(--ink); box-shadow: var(--shadow);
}
.image-dialog::backdrop { background: rgba(4, 12, 15, .82); backdrop-filter: blur(5px); }
.image-dialog figure { margin: 0; display: grid; grid-template-rows: minmax(0, 1fr) auto; max-height: calc(100vh - 2rem); }
.image-dialog img { width: 100%; max-height: calc(100vh - 7rem); object-fit: contain; background: #fff; }
.image-dialog figcaption { padding: .8rem 3.4rem .9rem 1rem; color: var(--muted); font-size: .9rem; }
.dialog-close {
  position: absolute; z-index: 2; top: .65rem; right: .65rem; width: 44px; min-height: 44px;
  border: 0; border-radius: 50%; background: rgba(7,18,22,.86); color: #fff; font-size: 1.65rem; line-height: 1;
}

.lab-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1rem; }
.lab-card { overflow: hidden; }
.lab-head { padding: 1rem 1.1rem; background: var(--graphite); color: #fff; }
.lab-kicker { color: #79dbe1; font-size: .68rem; font-weight: 900; letter-spacing: .11em; }
.lab-head h3 { margin: .2rem 0; line-height: 1.25; }
.lab-head p { margin: .35rem 0 0; color: #bad0d5; font-size: .85rem; }
.lab-body { padding: 1rem 1.1rem 1.2rem; }
.control-row { display: grid; grid-template-columns: minmax(120px, 1fr) 2fr auto; align-items: center; gap: .7rem; margin: .6rem 0; }
.control-row label { font-weight: 750; font-size: .86rem; }
.control-value { min-width: 75px; text-align: right; font-variant-numeric: tabular-nums; font-weight: 900; }
input[type="range"] { width: 100%; accent-color: var(--beam); }
.lab-output { margin-top: .8rem; padding: .8rem; border-radius: 12px; background: var(--surface-2); }
.lab-output strong { color: var(--focus); }
.meter-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: .55rem; margin-top: .8rem; }
.meter { font-size: .74rem; color: var(--muted); }
.meter span { display: block; height: 7px; margin-top: .2rem; border-radius: 99px; background: var(--line); overflow: hidden; }
.meter i { display: block; height: 100%; width: 50%; background: var(--beam); }
.sim-canvas { display: block; width: 100%; height: 220px; border-radius: 12px; background: #071216; }

.choice-set { display: grid; gap: .5rem; }
.choice-btn { width: 100%; text-align: left; border: 1px solid var(--line); border-radius: 11px; background: var(--surface); color: var(--ink); padding: .65rem .75rem; }
.choice-btn:hover, .choice-btn.selected { border-color: var(--beam); background: var(--beam-soft); }
.choice-btn.correct { border-color: var(--se); box-shadow: inset 4px 0 var(--se); }
.choice-btn.wrong { border-color: var(--danger); box-shadow: inset 4px 0 var(--danger); }
.feedback { min-height: 3rem; margin-top: .7rem; padding: .65rem .75rem; border-radius: 10px; background: var(--surface-2); font-size: .86rem; }

.sequence-list { list-style: none; padding: 0; display: grid; gap: .5rem; }
.sequence-item { display: grid; grid-template-columns: 32px 1fr auto; gap: .5rem; align-items: center; padding: .55rem; border: 1px solid var(--line); border-radius: 10px; background: var(--surface); }
.sequence-item .seq-no { width: 28px; height: 28px; display: grid; place-items: center; border-radius: 50%; background: var(--surface-2); font-weight: 900; }
.sequence-actions { display: flex; gap: .3rem; }
.sequence-actions button { min-height: 36px; min-width: 36px; border: 1px solid var(--line); border-radius: 8px; background: var(--surface); color: var(--ink); }

.tab-list { display: flex; flex-wrap: wrap; gap: .4rem; margin-bottom: .7rem; }
.tab-btn { border: 1px solid var(--line); border-radius: 999px; padding: .45rem .7rem; background: var(--surface); color: var(--ink); }
.tab-btn[aria-selected="true"] { border-color: var(--beam); background: var(--beam-soft); font-weight: 900; }
.compare-stage { min-height: 155px; padding: 1rem; border-radius: 12px; background: var(--surface-2); }
.signal-tag { display: inline-flex; align-items: center; gap: .35rem; padding: .2rem .55rem; border-radius: 999px; color: #071216; font-weight: 900; font-size: .72rem; }
.signal-tag.se { background: var(--se); }.signal-tag.bse { background: var(--bse); }.signal-tag.xray { background: var(--xray); color: #fff; }

.evidence-card { margin-top: 2rem; padding: 1.2rem; border-left: 6px solid var(--bse); }
.evidence-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: .7rem; }
.evidence-item { padding: .75rem; border-radius: 12px; background: var(--surface-2); }
.evidence-item b { display: block; color: var(--focus); font-size: .78rem; }
.evidence-item p { margin: .25rem 0 0; font-size: .88rem; }

.quiz-panel { margin-top: 2rem; padding: 1.2rem; }
.quiz-progress { color: var(--muted); font-size: .8rem; }
.quiz-question { font-size: 1.05rem; font-weight: 800; margin: .7rem 0; }
.quiz-score { display: grid; place-items: center; min-height: 210px; text-align: center; }
.quiz-score strong { display: block; font-size: 3rem; color: var(--focus); }

.page-footer { margin-top: 2rem; padding-top: 1.2rem; border-top: 1px solid var(--line); display: flex; justify-content: space-between; gap: 1rem; }
.footer-source { margin-top: 1rem; color: var(--muted); font-size: .78rem; }
.teacher-note { display: none; padding: .8rem; margin-top: .8rem; border: 1px dashed var(--xray); border-radius: 10px; background: color-mix(in srgb, var(--surface) 84%, var(--xray)); }
body.teacher .teacher-note { display: block; }

.toast { position: fixed; z-index: 100; left: 50%; bottom: 1.5rem; transform: translate(-50%, 150%); padding: .7rem 1rem; border-radius: 999px; background: var(--graphite); color: #fff; box-shadow: var(--shadow); transition: transform .25s; }
.toast.show { transform: translate(-50%, 0); }

/* 2026 refined digital laboratory interface */
body {
  background-image:
    radial-gradient(circle at 8% 4%, rgba(25,185,197,.07), transparent 24rem),
    linear-gradient(rgba(88,104,112,.035) 1px, transparent 1px),
    linear-gradient(90deg, rgba(88,104,112,.035) 1px, transparent 1px);
  background-size: auto, 42px 42px, 42px 42px;
}
.site-header { box-shadow: 0 8px 30px rgba(3,12,16,.18); }
.header-inner { min-height: 66px; }
.brand-mark { width: 34px; height: 34px; }
.brand-mark::before { left: 15px; height: 43px; }
.local-status {
  display: inline-flex; align-items: center; gap: .42rem; margin-left: 1rem; padding: .27rem .58rem;
  border: 1px solid rgba(255,255,255,.16); border-radius: 999px; color: #a8c3ca;
  font: 700 .65rem/1 var(--mono); letter-spacing: .08em;
}
.local-status i, .source-badge i, .mode-on i { width: 7px; height: 7px; border-radius: 50%; background: var(--se); box-shadow: 0 0 9px var(--se); }
.reading-progress { position: absolute; inset: auto 0 0; height: 2px; background: rgba(255,255,255,.08); }
.reading-progress i { display: block; width: 0; height: 100%; background: linear-gradient(90deg,var(--beam),#72e5ed); box-shadow: 0 0 12px var(--beam); }
.course-rail { position: sticky; top: 66px; z-index: 40; background: color-mix(in srgb,var(--surface) 91%,transparent); backdrop-filter: blur(14px); }
.rail-inner { padding: .45rem 0; }
.rail-link { font-weight: 650; transition: background .18s,color .18s,border-color .18s; }
.rail-link:hover { background: var(--surface-2); color: var(--ink); }
.rail-special { border-color: var(--beam); color: var(--focus); }
main { padding-top: 1.5rem; }
.hero { border: 1px solid rgba(255,255,255,.12); }
.hero::before {
  content: ""; position: absolute; inset: 0; pointer-events: none; opacity: .18;
  background-image: linear-gradient(rgba(255,255,255,.07) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.07) 1px,transparent 1px);
  background-size: 52px 52px;
  mask-image: linear-gradient(90deg,#000,transparent 75%);
}
.hero::after { opacity: .75; }
.hero-index { display: grid; grid-template-columns: minmax(0,1.05fr) minmax(340px,.75fr); gap: clamp(2rem,5vw,5rem); align-items: center; min-height: 620px; }
.hero-index h1 { max-width: 680px; }
.hero-index h1 span { color: #83e6eb; }
.hero-index .lead { max-width: 620px; }
.hero-facts { display: flex; flex-wrap: wrap; gap: 1.1rem; margin-top: 2rem; color: #a8c3ca; font: 700 .67rem/1.35 var(--mono); letter-spacing: .04em; }
.hero-facts span { display: grid; min-width: 74px; }
.hero-facts b { color: #fff; font-size: 1rem; }
.hero-specimen, .chapter-hero-visual {
  position: relative; z-index: 2; min-height: 0; padding: 0; overflow: hidden; border: 1px solid rgba(131,230,235,.45);
  border-radius: 22px; background: #071216; box-shadow: 0 32px 70px rgba(0,0,0,.38),0 0 0 8px rgba(25,185,197,.04); color: #fff;
}
.hero-specimen { aspect-ratio: 4/5; transform: rotate(1.2deg); }
.hero-specimen:hover, .chapter-hero-visual:hover { border-color: #83e6eb; transform: translateY(-3px); }
.hero-specimen img, .chapter-hero-visual img { width: 100%; height: 100%; object-fit: cover; filter: grayscale(1) contrast(1.08); opacity: .86; }
.specimen-scan { position: absolute; inset: 0; background: linear-gradient(transparent 48%,rgba(107,238,245,.2) 50%,transparent 52%); background-size: 100% 11px; mix-blend-mode: screen; opacity: .35; }
.specimen-ui, .visual-label, .scale-bar { position: absolute; z-index: 2; font: 700 .62rem/1.2 var(--mono); letter-spacing: .06em; text-align: left; }
.specimen-ui.top { top: 1rem; left: 1rem; display: flex; align-items: center; gap: .4rem; }
.specimen-ui.top i, .visual-label i { width: 6px; height: 6px; border-radius: 50%; background: var(--se); box-shadow: 0 0 8px var(--se); }
.specimen-ui.bottom { left: 1rem; bottom: 1rem; right: 1rem; padding-top: .7rem; border-top: 1px solid rgba(255,255,255,.35); }
.specimen-ui.bottom b { float: right; width: 30%; height: 2px; margin-top: .35rem; background: var(--beam); }
.scale-bar { right: 1rem; bottom: 3.6rem; display: grid; justify-items: end; color: #fff; }
.scale-bar i { display: block; width: 68px; height: 3px; margin-bottom: .3rem; background: #fff; }
.overview-panel {
  display: grid; grid-template-columns: auto 1fr auto; align-items: center; gap: 1.4rem; margin-top: -2rem; margin-inline: 2rem;
  position: relative; z-index: 3; padding: 1.25rem 1.5rem; border: 1px solid var(--line); border-radius: 22px; background: color-mix(in srgb,var(--surface) 94%,transparent); box-shadow: var(--shadow); backdrop-filter: blur(16px);
}
.progress-orbit, .mini-orbit { display: grid; place-items: center; border-radius: 50%; background: conic-gradient(var(--beam) calc(var(--pct)*1%),var(--surface-2) 0); }
.progress-orbit { width: 106px; height: 106px; }
.progress-orbit::before, .mini-orbit::before { content: ""; grid-area: 1/1; width: 82%; height: 82%; border-radius: 50%; background: var(--surface); }
.progress-orbit div { grid-area: 1/1; z-index: 1; display: grid; text-align: center; line-height: 1; }
.progress-orbit strong { font-size: 1.35rem; }
.progress-orbit span { margin-top: .3rem; color: var(--muted); font: 700 .58rem/1 var(--mono); letter-spacing: .09em; }
.overview-copy h2 { margin: .2rem 0; font-size: clamp(1.15rem,2vw,1.55rem); }
.overview-copy p:not(.section-kicker) { margin: .25rem 0; color: var(--muted); font-size: .88rem; }
.text-link { display: inline-block; margin-top: .35rem; text-decoration: none; font-weight: 800; }
.overview-stats { display: grid; grid-template-columns: repeat(3,auto); }
.overview-stats div { min-width: 90px; padding: .35rem .9rem; border-left: 1px solid var(--line); }
.overview-stats strong { display: block; font-size: 1.35rem; line-height: 1.1; }
.overview-stats small { color: var(--muted); font-size: .7rem; }
.overview-stats span { color: var(--muted); font-size: .72rem; }
.journey-strip { display: grid; grid-template-columns: repeat(4,1fr); margin: 2.3rem 0; border-block: 1px solid var(--line); }
.journey-step { position: relative; display: flex; gap: .8rem; padding: 1.1rem; }
.journey-step:not(:last-child)::after { content: "→"; position: absolute; right: -.35rem; color: var(--beam); }
.journey-step>span { color: var(--beam); font: 700 .72rem var(--mono); }
.journey-step div { display: grid; }
.journey-step b { font-size: .9rem; }
.journey-step small { color: var(--muted); }
.section-deck { max-width: 680px; margin: .45rem 0 0; color: var(--muted); }
.section-count { color: var(--line); font: 800 clamp(1.8rem,5vw,4rem)/1 var(--mono); letter-spacing: -.08em; }
.chapter-section { padding-top: 1rem; }
.chapter-grid { gap: 1.1rem; }
.chapter-card { grid-template-columns: 132px 1fr; padding: 0; overflow: hidden; min-height: 170px; }
.chapter-thumb { position: relative; align-self: stretch; overflow: hidden; background: var(--graphite); }
.chapter-thumb::after { content: ""; position: absolute; inset: 0; background: linear-gradient(135deg,transparent 45%,rgba(25,185,197,.45)); }
.chapter-thumb img { width: 100%; height: 100%; object-fit: cover; filter: grayscale(1) contrast(1.1); opacity: .76; transition: transform .35s,opacity .35s; }
.chapter-card:hover .chapter-thumb img { transform: scale(1.06); opacity: .95; }
.chapter-thumb i { position: absolute; z-index: 2; left: .8rem; bottom: .6rem; color: #fff; font: 800 1.5rem var(--mono); font-style: normal; }
.chapter-copy { align-self: center; padding: 1rem 1rem 2.2rem 0; }
.chapter-copy .chapter-phase { color: var(--beam); font: 750 .62rem var(--mono); letter-spacing: .07em; }
.chapter-copy strong { margin: .35rem 0 .1rem; font-size: 1.12rem; }
.chapter-copy>span:not(.chapter-mini-progress) { color: var(--muted); font-size: .78rem; }
.chapter-mini-progress { display: block; height: 4px; margin-top: .75rem; overflow: hidden; border-radius: 99px; background: var(--surface-2); }
.chapter-mini-progress i { display: block; height: 100%; background: linear-gradient(90deg,var(--beam),var(--se)); }
.chapter-status { position: absolute; right: 1rem; bottom: .65rem; display: flex; align-items: center; gap: .6rem; font: 700 .62rem var(--mono); letter-spacing: .05em; }
.chapter-status i { color: var(--beam); font-size: 1rem; font-style: normal; }
.chapter-card { position: relative; }
.chapter-card.done { border-color: color-mix(in srgb,var(--se) 70%,var(--line)); }
.closing-grid { margin-top: 2.2rem; }
.learning-spine { background: linear-gradient(135deg,var(--surface),color-mix(in srgb,var(--beam-soft) 55%,var(--surface))); }
.evidence-legend { display: flex; flex-wrap: wrap; gap: .7rem 1rem; margin-top: 1.2rem; color: var(--muted); font-size: .76rem; }
.evidence-legend span { display: inline-flex; align-items: center; gap: .35rem; }
.evidence-legend i { width: 8px; height: 8px; border-radius: 50%; }
.se-dot{background:var(--se)}.bse-dot{background:var(--bse)}.xray-dot{background:var(--xray)}.beam-dot{background:var(--beam)}
.mode-on { display: flex; align-items: center; gap: .5rem; color: var(--se); font-weight: 800; }

/* Chapter experience */
.chapter-hero { display: grid; grid-template-columns: minmax(0,1.1fr) minmax(320px,.75fr); gap: clamp(2rem,5vw,4rem); align-items: center; min-height: 500px; }
.chapter-hero h1 { font-size: clamp(2.4rem,5vw,4.7rem); }
.chapter-meta { display: flex; flex-wrap: wrap; gap: .5rem; margin-top: 1.5rem; }
.chapter-meta span { padding: .35rem .6rem; border: 1px solid rgba(255,255,255,.22); border-radius: 999px; color: #a8c3ca; font: 700 .62rem var(--mono); letter-spacing: .04em; }
.chapter-hero-visual { aspect-ratio: 4/3; }
.chapter-hero-visual img { object-fit: contain; background: #fff; }
.visual-grid { position: absolute; inset: 0; background-image: linear-gradient(rgba(25,185,197,.12) 1px,transparent 1px),linear-gradient(90deg,rgba(25,185,197,.12) 1px,transparent 1px); background-size: 32px 32px; mix-blend-mode: screen; }
.visual-label { top: .8rem; left: .8rem; display: flex; align-items: center; gap: .4rem; padding: .35rem .5rem; background: rgba(3,12,16,.75); border-radius: 5px; }
.chapter-hero-visual .scale-bar { bottom: .8rem; }
.chapter-jumps { display: grid; grid-template-columns: repeat(5,1fr); margin-top: 1rem; border: 1px solid var(--line); border-radius: 15px; background: var(--surface); overflow: hidden; }
.chapter-jumps a { display: flex; align-items: center; gap: .45rem; min-height: 52px; padding: .65rem .75rem; color: var(--muted); text-decoration: none; font-size: .75rem; font-weight: 750; }
.chapter-jumps a:not(:last-child) { border-right: 1px solid var(--line); }
.chapter-jumps a:hover { color: var(--ink); background: var(--beam-soft); }
.chapter-jumps span { color: var(--beam); font: 700 .62rem var(--mono); }
.chapter-overview { grid-template-columns: 1fr 1fr; }
.mission-panel { position: relative; overflow: hidden; padding: 1.45rem; }
.mission-panel::after { content: "MISSION"; position: absolute; right: -1rem; bottom: -1.1rem; color: var(--surface-2); font: 900 4rem/1 var(--mono); letter-spacing: -.1em; }
.mission-panel>* { position: relative; z-index: 1; }
.mission-line { color: var(--beam); font: 700 .65rem var(--mono); letter-spacing: .06em; }
.progress-panel { display: grid; grid-template-columns: auto 1fr; align-items: center; gap: 1.2rem; }
.mini-orbit { width: 88px; height: 88px; flex: 0 0 auto; }
.mini-orbit strong { grid-area: 1/1; z-index: 1; font-size: 1.15rem; }
.progress-panel h2 { margin-bottom: .2rem; }
.progress-panel p { margin: .25rem 0 .65rem; }
.concept { position: relative; min-height: 180px; padding: 1.25rem; border: 1px solid var(--line); border-left: 1px solid var(--line); border-top: 4px solid var(--beam); }
.concept>span { display: block; margin-bottom: 1.2rem; color: var(--beam); font: 700 .7rem var(--mono); }
.concept strong { font-size: 1.05rem; }
.slide-gallery { grid-template-columns: 1.4fr .8fr; grid-template-rows: repeat(2,minmax(150px,1fr)); }
.slide-figure:first-child { grid-row: 1/3; }
.slide-image-wrap { position: relative; height: 185px; overflow: hidden; background: #e9edef; }
.slide-figure:first-child .slide-image-wrap { height: 410px; }
.slide-image-wrap img { transition: transform .3s; }
.slide-figure:hover img { transform: scale(1.025); }
.image-index { position: absolute; left: .7rem; top: .7rem; padding: .25rem .4rem; border-radius: 4px; background: rgba(3,12,16,.78); color: #fff; font: 700 .62rem var(--mono); }
.image-expand { position: absolute; right: .7rem; top: .7rem; width: 30px; height: 30px; display: grid; place-items: center; border-radius: 50%; background: rgba(3,12,16,.78); color: #fff; }
.source-badge { gap: .4rem; }
.gallery-note { color: var(--muted); font-size: .75rem; }
.lab-section, #concepts, #evidence, #quiz { scroll-margin-top: 130px; }
.lab-grid { gap: 1.15rem; }
.lab-card { border-color: color-mix(in srgb,var(--line) 82%,transparent); transition: transform .2s,border-color .2s,box-shadow .2s; }
.lab-card:hover { transform: translateY(-2px); border-color: var(--beam); box-shadow: var(--shadow); }
.lab-card.completed { border-color: color-mix(in srgb,var(--se) 72%,var(--line)); }
.lab-card.completed .lab-head { box-shadow: inset 4px 0 var(--se); }
.lab-head { min-height: 150px; padding: 1.15rem 1.25rem; background: radial-gradient(circle at 90% 0,rgba(25,185,197,.18),transparent 38%),var(--graphite); }
.lab-topline { display: flex; align-items: center; justify-content: space-between; gap: .7rem; }
.lab-status { padding: .25rem .48rem; border: 1px solid rgba(255,255,255,.18); border-radius: 999px; color: #a8c3ca; font: 700 .6rem var(--mono); }
.lab-card.completed .lab-status { border-color: var(--se); color: #9bf0bb; }
.lab-head h3 { margin-top: .75rem; font-size: 1.2rem; }
.lab-body { padding: 1.2rem 1.25rem 1.35rem; }
.evidence-card { padding: 1.5rem; border: 1px solid var(--line); border-top: 5px solid var(--bse); }
.evidence-title { display: flex; align-items: end; justify-content: space-between; gap: 1rem; margin-bottom: 1rem; }
.evidence-title h2 { margin: .1rem 0 0; }
.evidence-title>span { color: var(--bse); font: 800 .68rem var(--mono); letter-spacing: .08em; }
.evidence-item { position: relative; min-height: 175px; padding: 1rem; border: 1px solid transparent; }
.evidence-item>span { display: block; margin-bottom: 1rem; color: var(--muted); font: 700 .65rem var(--mono); }
.evidence-item.support{border-top:3px solid var(--se)}.evidence-item.limit{border-top:3px solid var(--xray)}.evidence-item.next{border-top:3px solid var(--beam)}.evidence-item.source{border-top:3px solid var(--bse)}
.quiz-panel { padding: 0; overflow: hidden; }
.quiz-intro { display: flex; align-items: center; justify-content: space-between; gap: 1rem; padding: 1.5rem; color: #fff; background: radial-gradient(circle at 85% 0,rgba(25,185,197,.28),transparent 35%),var(--graphite); }
.quiz-intro h2 { margin: .1rem 0; font-size: 2rem; }
.quiz-intro p:not(.section-kicker) { margin: 0; color: #bad0d5; }
.quiz-count { display: grid; text-align: right; color: #fff; font: 850 2.2rem/1 var(--mono); }
.quiz-count small { margin-top: .3rem; color: #79dbe1; font-size: .55rem; letter-spacing: .08em; }
#quizMount { padding: 1.5rem; }
.quiz-progress { display: flex; justify-content: space-between; color: var(--muted); font: 700 .67rem var(--mono); letter-spacing: .06em; }
.quiz-step-track { height: 4px; margin: .65rem 0 1.2rem; overflow: hidden; border-radius: 99px; background: var(--surface-2); }
.quiz-step-track i { display: block; height: 100%; background: var(--beam); }
.quiz-question { max-width: 800px; margin-bottom: 1.2rem; font-size: 1.2rem; }
.choice-btn { display: grid; grid-template-columns: 30px 1fr; align-items: center; gap: .7rem; min-height: 58px; }
.choice-btn>span { width: 28px; height: 28px; display: grid; place-items: center; border-radius: 50%; background: var(--surface-2); color: var(--muted); font: 700 .7rem var(--mono); }
.choice-btn.correct>span { background: var(--se); color: #fff; }
.choice-btn.wrong>span { background: var(--danger); color: #fff; }
.feedback { margin-top: 1rem; }
.page-footer { margin-top: 3rem; }
.footer-source { max-width: 900px; margin-inline: auto; text-align: center; }
.btn { transition: transform .18s,box-shadow .18s,background .18s; }

@media (max-width: 900px) {
  .mission-grid, .dashboard-grid { grid-template-columns: 1fr 1fr; }
  .chapter-grid, .lab-grid { grid-template-columns: 1fr; }
  .concept-grid { grid-template-columns: 1fr 1fr; }
  .slide-gallery { grid-template-columns: 1fr 1fr; }
  .evidence-grid { grid-template-columns: 1fr 1fr; }
  .hero-index, .chapter-hero { grid-template-columns: 1fr; min-height: 0; }
  .hero-specimen { width: min(480px,100%); aspect-ratio: 4/3; transform: none; justify-self: center; }
  .overview-panel { grid-template-columns: auto 1fr; margin-inline: 1rem; }
  .overview-stats { grid-column: 1/-1; border-top: 1px solid var(--line); padding-top: .8rem; }
  .overview-stats div:first-child { border-left: 0; }
  .journey-strip { grid-template-columns: 1fr 1fr; }
  .journey-step:nth-child(2)::after { display: none; }
  .chapter-jumps { grid-template-columns: repeat(3,1fr); }
  .chapter-jumps a:nth-child(3) { border-right: 0; }
  .chapter-jumps a:nth-child(n+4) { border-top: 1px solid var(--line); }
  .slide-figure:first-child .slide-image-wrap { height: 310px; }
}

@media (max-width: 620px) {
  .header-inner { width: min(100% - 1rem, var(--max)); min-height: 62px; }
  .brand-copy small { display: none; }
  .header-actions .label { display: none; }
  .site-back .label { display: none; }
  main { width: min(100% - 1rem, var(--max)); padding-top: 1rem; }
  .hero { border-radius: 20px; padding: 1.5rem; }
  .mission-grid, .dashboard-grid, .concept-grid, .slide-gallery, .evidence-grid { grid-template-columns: 1fr; }
  .slide-image-wrap { height: 230px; }
  .chapter-card { grid-template-columns: 100px 1fr; min-height: 150px; }
  .chapter-no { width: 44px; height: 44px; border-radius: 12px; }
  .chapter-status { grid-column: 2; text-align: left; }
  .control-row { grid-template-columns: 1fr auto; }
  .control-row input { grid-column: 1 / -1; grid-row: 2; }
  .page-footer { flex-direction: column; }
  .page-footer .btn { width: 100%; }
  .local-status { display: none; }
  .course-rail { top: 62px; }
  .hero-index { gap: 1.5rem; }
  .hero-index h1 { font-size: clamp(2.35rem,12vw,3.45rem); }
  .hero-specimen { aspect-ratio: 1/1; }
  .hero-facts { display: grid; grid-template-columns: 1fr 1fr; }
  .overview-panel { grid-template-columns: 1fr; margin: 1rem 0 0; }
  .progress-orbit { width: 90px; height: 90px; }
  .overview-stats { grid-column: auto; grid-template-columns: 1fr 1fr 1fr; }
  .overview-stats div { min-width: 0; padding-inline: .45rem; }
  .overview-stats strong { font-size: 1.05rem; }
  .overview-stats span { font-size: .62rem; }
  .journey-strip { grid-template-columns: 1fr; }
  .journey-step:not(:last-child)::after { content: "↓"; right: 1rem; bottom: -.6rem; }
  .chapter-copy { padding-right: .8rem; }
  .chapter-copy>span:not(.chapter-mini-progress) { display: none; }
  .chapter-status { right: .75rem; bottom: .55rem; }
  .closing-grid, .chapter-overview { grid-template-columns: 1fr; }
  .chapter-hero-visual { aspect-ratio: 1/1; }
  .chapter-jumps { grid-template-columns: 1fr 1fr; }
  .chapter-jumps a { border-top: 1px solid var(--line); border-right: 0 !important; }
  .chapter-jumps a:nth-child(odd) { border-right: 1px solid var(--line) !important; }
  .chapter-jumps a:first-child, .chapter-jumps a:nth-child(2) { border-top: 0; }
  .progress-panel { grid-template-columns: 1fr; }
  .slide-gallery { grid-template-rows: auto; }
  .slide-figure:first-child { grid-row: auto; }
  .slide-figure:first-child .slide-image-wrap { height: 230px; }
  .concept { min-height: 0; }
  .evidence-item { min-height: 0; }
  .quiz-intro { align-items: flex-end; }
  .quiz-intro h2 { font-size: 1.55rem; }
  #quizMount { padding: 1rem; }
}
.cw-mark { display:inline-flex; align-items:center; white-space:nowrap; color:#b9cbd0; font:700 .72rem var(--mono); letter-spacing:.08em; }
.site-credit { margin-top:1rem; padding-top:.75rem; border-top:1px solid var(--line); text-align:center; color:var(--muted); font-size:.76rem; }
.site-credit a { color:var(--focus); text-decoration:none; }
@media (max-width:620px) { .cw-mark { font-size:.64rem; } .site-credit { font-size:.7rem; line-height:1.5; } }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; animation: none !important; }
}

/* Compact interaction density: keep each lab at its natural height. */
.lab-grid { align-items: start; }
.lab-card { align-self: start; height: max-content; }
.lab-head { min-height: 0; }
.choice-set { align-items: start; }
.choice-set:has(> .choice-btn) { grid-template-columns: repeat(auto-fit, minmax(min(100%, 260px), 1fr)); }
.choice-set > .choice-btn { width: 100%; min-height: 44px; height: auto; padding: .55rem .7rem; line-height: 1.45; }
.quiz-panel .choice-set { grid-template-columns: 1fr; max-width: 860px; }
.quiz-panel .choice-btn { width: 100%; }
.feedback { min-height: 2.2rem; }
.sequence-item { min-height: 0; }
select { max-width: 100%; }

@media (max-width: 620px) {
  .choice-set:has(> .choice-btn) { grid-template-columns: 1fr; }
  .choice-set > .choice-btn { min-height: 44px; }
}

/* High-fidelity teaching simulators: compact controls, large readable canvas. */
.advanced-sim-shell { display: grid; gap: .75rem; }
.advanced-sim-stage { position: relative; overflow: hidden; border: 1px solid var(--line); border-radius: 12px; background: var(--graphite); }
.advanced-sim-canvas { display: block; width: 100%; height: 300px; background: #071216; cursor: crosshair; }
.advanced-sim-legend { padding: .45rem .7rem; color: #b9cbd0; font-size: .72rem; border-top: 1px solid rgba(255,255,255,.12); }
.advanced-sim-challenge { padding: .65rem .75rem; border-left: 3px solid var(--focus); border-radius: 8px; background: var(--surface-2); color: var(--text); font-size: .82rem; line-height: 1.55; }
.advanced-sim-presets { display: flex; align-items: center; gap: .45rem; flex-wrap: wrap; }
.advanced-sim-presets[hidden] { display: none; }
.advanced-sim-presets > span { color: var(--muted); font-size: .75rem; font-weight: 750; margin-right: .15rem; }
.advanced-sim-control-hint { color: var(--muted); font-size: .74rem; }
.advanced-sim-controls-wrap { display: grid; gap: .55rem; }
.advanced-sim-group { border: 1px solid var(--line); border-radius: 10px; background: var(--surface-2); }
.advanced-sim-group summary { display: flex; justify-content: space-between; align-items: center; cursor: pointer; padding: .55rem .7rem; color: var(--text); font-size: .78rem; font-weight: 750; list-style-position: inside; }
.advanced-sim-group summary span { color: var(--muted); font: 700 .68rem var(--mono); }
.advanced-sim-group .advanced-sim-controls { padding: 0 .6rem .6rem; }
.advanced-sim-controls { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: .6rem; }
.advanced-sim-control { display: grid; gap: .3rem; min-width: 0; padding: .55rem .65rem; border: 1px solid var(--line); border-radius: 10px; background: var(--surface); }
.advanced-sim-control span { font-size: .77rem; font-weight: 750; }
.advanced-sim-control select { width: 100%; min-height: 40px; }
.advanced-sim-control input { width: 100%; accent-color: var(--beam); }
.advanced-sim-control output { color: var(--focus); font: 750 .72rem var(--mono); text-align: right; }
.advanced-sim-output { padding: .7rem .8rem; border-left: 3px solid var(--beam); border-radius: 8px; background: var(--beam-soft); font-size: .86rem; }
.advanced-sim-output p { margin: .55rem 0 0; }
.advanced-sim-actions { display: flex; align-items: center; gap: .6rem; flex-wrap: wrap; }
.advanced-sim-status { color: var(--se); font-size: .76rem; }
.virtual-sim-panel { display: grid; gap: .65rem; margin-top: .1rem; padding: .7rem; border: 1px solid var(--line); border-radius: 12px; background: var(--surface-2); }
.virtual-sim-task { display: grid; grid-template-columns: minmax(180px, .34fr) 1fr; gap: .65rem; align-items: stretch; }
.virtual-sim-goal { align-self: stretch; padding: .65rem .75rem; border-left: 3px solid var(--focus); border-radius: 8px; background: var(--surface); color: var(--text); font-size: .82rem; line-height: 1.55; }
.virtual-sim-goal small { color: var(--muted); }
.virtual-sim-captures { display: flex; align-items: center; gap: .55rem; flex-wrap: wrap; }
.virtual-sim-captures > div { display: inline-flex; align-items: center; gap: .45rem; }
.virtual-sim-captures span { color: var(--muted); font: 700 .72rem var(--mono); }
.virtual-sim-compare { overflow-x: auto; padding: .55rem .65rem; border-top: 1px solid var(--line); color: var(--text); font-size: .8rem; line-height: 1.55; }
.virtual-sim-table { width: 100%; min-width: 420px; margin: .45rem 0; border-collapse: collapse; font-size: .76rem; }
.virtual-sim-table th, .virtual-sim-table td { padding: .35rem .45rem; border-bottom: 1px solid var(--line); text-align: left; }
.virtual-sim-table th { color: var(--muted); font-weight: 750; }
@media (max-width: 900px) { .advanced-sim-controls { grid-template-columns: 1fr 1fr; } }
@media (max-width: 620px) { .advanced-sim-canvas { height: 260px; } .advanced-sim-controls { grid-template-columns: 1fr; } .virtual-sim-task { grid-template-columns: 1fr; } .virtual-sim-captures { align-items: stretch; flex-direction: column; } .virtual-sim-captures > div { justify-content: space-between; } }

/* ── 間隔複習（spaced retrieval）── */
.quiz-review-tag{display:inline-block;margin-bottom:.6rem;padding:.2rem .6rem;border-radius:999px;
  font-size:.72rem;letter-spacing:.06em;font-weight:700;
  background:color-mix(in srgb,var(--accent,#e8871e) 18%,transparent);
  color:var(--accent,#e8871e);border:1px solid color-mix(in srgb,var(--accent,#e8871e) 40%,transparent)}
.quiz-retrieval-note{margin-top:.7rem;font-size:.82rem;opacity:.75}
.rail-link.rail-review{font-weight:700}
.review-stats{list-style:none;margin:.6rem 0 1rem;padding:0;display:grid;gap:.5rem}
.review-stats li{display:flex;align-items:baseline;gap:.6rem}
.review-stats b{font-size:1.5rem;line-height:1;min-width:2.6ch;text-align:right}
.review-stats span{font-size:.82rem;opacity:.8}

/* ── 公式（原生 MathML，無外部字型與 CDN）── */
.concept-formula{margin:.7rem 0 .3rem;padding:.65rem .8rem;border-radius:.6rem;
  background:color-mix(in srgb,currentColor 6%,transparent);
  border-left:3px solid var(--accent,#e8871e);overflow-x:auto}
.concept-formula .fx{font-size:1.05rem;font-family:"Cambria Math","STIX Two Math",Georgia,serif;white-space:nowrap}
.concept-formula .fx sub{font-size:.7em}
.concept-formula .fx sup{font-size:.72em}
.concept-formula .vars{display:block;margin-top:.4rem;font-size:.78rem;opacity:.78;white-space:normal}
@media print{.concept-formula{border-left-color:#666}}