:root{
  --ink:#0f2440;
  --ink-2:#1f3864;
  --blue:#2e5c8a;
  --teal:#0f9d8a;
  --teal-2:#3bb273;
  --amber:#e9932f;
  --coral:#cf6338;
  --muted:#5d7590;
  --line:rgba(31,56,100,.12);
  --glass:rgba(255,255,255,.84);
  --glass-strong:rgba(255,255,255,.9);
  --shadow:0 24px 70px rgba(31,56,100,.14);
  --radius:24px;
  --font:"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans CJK SC",system-ui,-apple-system,sans-serif;
}
*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;color:var(--ink);font-family:var(--font);
  background:
    radial-gradient(1000px 650px at 86% 2%, rgba(255,190,110,.5), transparent 62%),
    radial-gradient(760px 520px at 8% 16%, rgba(80,185,255,.42), transparent 66%),
    linear-gradient(180deg,#f6fbff 0%,#dff2ff 40%,#cfebff 72%,#f8fbff 100%);
  overflow-x:hidden;
}
::selection{background:rgba(15,157,138,.2)}
a{color:inherit;text-decoration:none}
button{font-family:var(--font)}

/* ---------- stage ---------- */
.stage{position:fixed;inset:0;z-index:0;overflow:hidden;pointer-events:none}
.canvas-layer{position:absolute;inset:0;width:100%;height:100%;display:block;pointer-events:auto;touch-action:pan-y;transition:opacity .9s ease}
.canvas-energy{opacity:0}
.stage.energy .canvas-tokamak{opacity:0;pointer-events:none}
.stage.energy .canvas-energy{opacity:1}
.stage-glow{position:absolute;inset:0;pointer-events:none;
  background:
    radial-gradient(680px 420px at 74% 38%, rgba(255,255,255,.55), transparent 70%),
    radial-gradient(520px 380px at 30% 80%, rgba(135,215,255,.22), transparent 70%);
  opacity:.22}

/* ---------- topbar ---------- */
.topbar{position:fixed;top:0;left:0;right:0;height:74px;z-index:60;display:flex;align-items:center;justify-content:space-between;
  padding:0 4vw;background:linear-gradient(180deg,rgba(251,253,255,.94),rgba(251,253,255,.62));
  backdrop-filter:blur(16px);border-bottom:1px solid rgba(31,56,100,.08)}
.brand{display:flex;align-items:center;gap:12px}
.brand-mark{width:38px;height:38px;border-radius:11px;background:linear-gradient(135deg,var(--ink),var(--blue));color:#fff;
  display:grid;place-items:center;font-size:13px;font-weight:800;letter-spacing:.02em;box-shadow:0 8px 20px rgba(31,56,100,.22)}
.brand-text{font-size:11px;letter-spacing:.18em;font-weight:700;color:var(--ink);display:flex;flex-direction:column;line-height:1.35}
.brand-text em{font-style:normal;font-size:9px;letter-spacing:.16em;color:var(--muted);font-weight:500}
.nav{display:flex;gap:6px;padding:5px;border:1px solid rgba(31,56,100,.1);border-radius:999px;background:rgba(255,255,255,.55)}
.nav a{font-size:12px;padding:8px 16px;border-radius:999px;color:var(--muted);transition:.25s}
.nav a:hover,.nav a.active{color:var(--ink);background:#fff;box-shadow:0 4px 14px rgba(31,56,100,.1)}
.top-meta{font-size:10px;letter-spacing:.12em;color:var(--muted)}
.progress{position:fixed;top:0;left:0;right:0;height:2px;z-index:70;background:transparent}
.progress span{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--teal),#49b7ff,var(--amber));transition:width .1s linear}

/* ---------- scroll content ---------- */
.scroll-content{position:relative;z-index:10}
.hero{min-height:100svh;display:flex;align-items:center;padding:120px 6vw 80px;position:relative}
.hero-inner{max-width:780px}
.eyebrow{font-size:11px;letter-spacing:.3em;color:var(--teal);font-weight:700;margin:0 0 22px}
.hero h1{font-size:clamp(56px,8.4vw,112px);line-height:.94;letter-spacing:-.055em;margin:0;font-weight:800;color:var(--ink)}
.hero h1 span{background:linear-gradient(110deg,var(--blue) 10%,var(--teal) 55%,#6cc7ff 95%);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero-sub{font-size:clamp(16px,1.5vw,20px);color:var(--muted);margin:26px 0 44px;line-height:1.7}
.hero-stats{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:0;max-width:720px;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.stat{padding:20px 22px 20px 0}
.stat + .stat{padding-left:22px;border-left:1px solid var(--line)}
.stat strong{display:block;font-size:clamp(22px,2.4vw,32px);letter-spacing:-.03em;color:var(--ink);font-weight:800}
.stat span{display:block;font-size:11px;line-height:1.55;color:var(--muted);margin-top:6px}
.scroll-hint{display:flex;align-items:center;gap:14px;margin-top:54px;font-size:11px;letter-spacing:.14em;color:var(--muted)}
.scroll-line{display:block;width:54px;height:1px;background:linear-gradient(90deg,var(--teal),transparent);position:relative;overflow:hidden}
.scroll-line::after{content:"";position:absolute;left:-30%;top:0;width:30%;height:100%;background:var(--ink);animation:slide 2.2s infinite}
@keyframes slide{to{left:110%}}
.hero-note{position:absolute;left:6vw;bottom:26px;font-size:9px;color:rgba(93,117,144,.75);letter-spacing:.02em;max-width:60vw}

.section{position:relative;min-height:100svh;display:flex;align-items:center;padding:12vh 6vw}
.section-inner{width:100%;display:flex}
.card{width:min(440px,94vw);padding:34px 32px;border-radius:var(--radius);background:var(--glass);
  border:1px solid rgba(255,255,255,.92);box-shadow:var(--shadow);backdrop-filter:blur(20px) saturate(1.1);
  position:relative;overflow:hidden}
.card::before{content:"";position:absolute;left:0;top:26px;width:3px;height:44px;border-radius:0 3px 3px 0;background:linear-gradient(180deg,var(--teal),#6fc9ff)}
.kicker{font-size:10px;letter-spacing:.22em;color:var(--teal);font-weight:700;margin:0 0 12px}
.card h2{font-size:clamp(30px,3.2vw,44px);line-height:1.12;letter-spacing:-.04em;margin:0 0 4px;color:var(--ink);font-weight:800}
.part-en{font-size:10px;letter-spacing:.2em;text-transform:uppercase;color:var(--blue);margin:0 0 18px}
.card p{font-size:13.5px;line-height:1.85;color:#334b66;margin:0 0 13px}
.card p:last-child{margin-bottom:0}
.tags{display:flex;flex-wrap:wrap;gap:7px;margin-top:20px}
.tags span{font-size:10px;letter-spacing:.06em;padding:6px 10px;border-radius:999px;border:1px solid rgba(15,157,138,.25);color:#0b7d70;background:rgba(15,157,138,.07)}
.mini-spec{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin-top:22px;padding-top:18px;border-top:1px solid var(--line)}
.mini-spec span{display:block;font-size:9px;letter-spacing:.12em;color:var(--muted);text-transform:uppercase}
.mini-spec strong{display:block;font-size:13px;margin-top:3px;color:var(--ink)}
.spec-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin-top:20px}
.spec-grid div{padding:10px 0;border-top:1px solid var(--line)}
.spec-grid span{display:block;font-size:9px;letter-spacing:.1em;color:var(--muted)}
.spec-grid strong{display:block;font-size:14px;margin-top:3px}
.fine{font-size:10px!important;color:var(--muted)!important;margin-top:18px!important}

.tokamak-intro .card{width:min(520px,94vw);background:rgba(255,255,255,.92)}
.part-index{position:fixed;left:6vw;bottom:28px;font-size:10px;letter-spacing:.2em;color:rgba(31,56,100,.42);z-index:30;pointer-events:none}
.step-chip{position:fixed;right:5vw;bottom:26px;z-index:35;display:flex;align-items:center;gap:10px;padding:9px 14px;border-radius:999px;
  background:rgba(255,255,255,.78);border:1px solid rgba(255,255,255,.95);box-shadow:0 10px 30px rgba(31,56,100,.1);backdrop-filter:blur(14px);
  font-size:10px;letter-spacing:.14em;color:var(--muted)}
.step-chip span:first-child{font-weight:800;color:var(--ink)}
.step-chip i{width:18px;height:1px;background:var(--line)}

.parts-panel{position:fixed;right:2.4vw;top:50%;transform:translateY(-50%);z-index:32;width:194px;padding:16px 14px;border-radius:18px;
  background:rgba(255,255,255,.66);border:1px solid rgba(255,255,255,.92);box-shadow:0 16px 40px rgba(31,56,100,.1);backdrop-filter:blur(16px)}
.panel-title{font-size:9px;letter-spacing:.2em;color:var(--muted);margin:0 0 10px;text-transform:uppercase}
.parts-panel ol{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:2px}
.parts-panel li{display:flex;align-items:baseline;gap:8px;padding:7px 8px;border-radius:9px;font-size:11.5px;color:#435b74;transition:.25s;cursor:default}
.parts-panel li span{font-size:9px;color:#9aadc1;font-variant-numeric:tabular-nums}
.parts-panel li em{font-style:normal;font-size:8.5px;color:#9aadc1;margin-left:auto}
.parts-panel li.active{background:linear-gradient(90deg,rgba(15,157,138,.12),rgba(73,183,255,.08));color:var(--ink);font-weight:700}
.parts-panel li.active span{color:var(--teal)}
.parts-panel li.active em{color:var(--blue)}

/* ---------- callouts ---------- */
.callout-layer{position:fixed;inset:0;z-index:28;pointer-events:none}
.callout{position:absolute;left:0;top:0;display:flex;align-items:center;gap:0;opacity:0;transition:opacity .35s ease;will-change:transform}
.callout.visible{opacity:1}
.callout-dot{width:9px;height:9px;border-radius:50%;background:var(--teal);box-shadow:0 0 0 4px rgba(15,157,138,.16),0 0 18px rgba(15,157,138,.5);flex:none}
.callout-line{width:52px;height:1px;background:linear-gradient(90deg,rgba(15,157,138,.7),rgba(15,157,138,.15));flex:none}
.callout-box{background:rgba(255,255,255,.9);border:1px solid rgba(255,255,255,.96);box-shadow:0 14px 34px rgba(31,56,100,.13);
  border-radius:12px;padding:9px 12px;backdrop-filter:blur(12px);min-width:132px}
.callout-box strong{display:block;font-size:11.5px;letter-spacing:.02em;color:var(--ink)}
.callout-box span{display:block;font-size:9.5px;line-height:1.45;color:var(--muted);margin-top:2px}

/* ---------- energy ---------- */
.energy-intro .card{width:min(520px,94vw);background:rgba(255,255,255,.92)}
.energy-section{min-height:160svh;align-items:flex-end;padding-bottom:16vh}
.energy-ui{position:fixed;left:5vw;right:5vw;top:96px;z-index:34;pointer-events:none}
.energy-head{display:flex;align-items:flex-start;justify-content:space-between;gap:20px}
.energy-head h2{font-size:clamp(26px,3.4vw,46px);line-height:1.12;letter-spacing:-.04em;margin:0;color:var(--ink);font-weight:800}
.energy-total{text-align:right;flex:none;padding-top:4px}
.energy-total span{display:block;font-size:9px;letter-spacing:.18em;color:var(--muted);text-transform:uppercase}
.energy-total strong{display:block;font-size:clamp(34px,4vw,56px);letter-spacing:-.05em;line-height:1;color:var(--ink);font-weight:800;font-variant-numeric:tabular-nums}
.energy-total em{font-style:normal;font-size:10px;letter-spacing:.14em;color:var(--muted)}
.energy-dash{position:fixed;left:5vw;right:5vw;bottom:4.5vh;z-index:36;pointer-events:auto;
  background:rgba(255,255,255,.8);border:1px solid rgba(255,255,255,.96);box-shadow:0 20px 60px rgba(31,56,100,.14);
  border-radius:18px;padding:14px 18px 15px;backdrop-filter:blur(18px)}
.year-toggle{position:absolute;right:16px;top:-46px;display:flex;gap:4px;padding:4px;border-radius:999px;background:rgba(255,255,255,.8);border:1px solid rgba(31,56,100,.1);box-shadow:0 8px 24px rgba(31,56,100,.1)}
.year-toggle button{border:0;background:transparent;padding:7px 16px;border-radius:999px;font-size:11px;color:var(--muted);cursor:pointer;transition:.25s}
.year-toggle button.active{background:var(--ink);color:#fff;box-shadow:0 6px 16px rgba(31,56,100,.25)}
.mix-bar{display:flex;height:10px;border-radius:999px;overflow:hidden;background:#e8f1f9;margin-bottom:12px}
.mix-bar span{display:block;height:100%;transition:width .9s cubic-bezier(.2,.7,.2,1);min-width:0}
.mix-legend{display:flex;flex-wrap:wrap;gap:10px 18px;align-items:center}
.legend-item{display:flex;align-items:center;gap:7px;font-size:10.5px;color:#415a75}
.legend-item i{width:7px;height:7px;border-radius:50%;display:block}
.legend-item strong{font-weight:700;color:var(--ink);font-variant-numeric:tabular-nums}
.legend-item em{font-style:normal;color:var(--muted);font-size:9px}
.energy-note{position:fixed;left:5vw;bottom:calc(4.5vh + 96px);z-index:34;max-width:min(560px,82vw);pointer-events:none;
  padding:13px 16px;border-radius:14px;background:rgba(255,255,255,.7);border:1px solid rgba(255,255,255,.9);backdrop-filter:blur(14px);
  display:flex;flex-direction:column;gap:3px}
.energy-note strong{font-size:12px;color:var(--ink);font-weight:700}
.energy-note span{font-size:10px;color:var(--muted);line-height:1.5}
.source-labels{position:fixed;inset:0;z-index:30;pointer-events:none}
.source-label{position:absolute;transform:translate(-50%,-50%);min-width:118px;padding:8px 10px;border-radius:11px;
  background:rgba(255,255,255,.86);border:1px solid rgba(255,255,255,.96);box-shadow:0 12px 30px rgba(31,56,100,.12);backdrop-filter:blur(10px);
  transition:opacity .5s ease}
.source-label .sl-top{display:flex;align-items:center;gap:6px}
.source-label i{width:7px;height:7px;border-radius:50%;display:block;flex:none}
.source-label strong{font-size:11px;color:var(--ink);font-weight:700;white-space:nowrap}
.source-label .sl-val{display:flex;align-items:baseline;gap:5px;margin-top:3px}
.source-label b{font-size:13px;letter-spacing:-.02em;color:var(--ink);font-variant-numeric:tabular-nums}
.source-label em{font-style:normal;font-size:9px;color:var(--muted)}
.source-label.ghost{opacity:.72;border-style:dashed}
.closing{min-height:86svh;align-items:center;padding-top:16vh;padding-bottom:16vh}
.closing-card{width:min(620px,94vw)}
.closing-meta{display:grid;grid-template-columns:repeat(3,1fr);gap:10px;margin-top:24px;padding-top:18px;border-top:1px solid var(--line)}
.closing-meta span{display:block;font-size:9px;letter-spacing:.12em;color:var(--muted);text-transform:uppercase}
.closing-meta strong{display:block;font-size:12px;margin-top:3px;color:var(--ink)}

/* ---------- fallback ---------- */
.webgl-fallback{position:fixed;inset:0;z-index:80;background:rgba(238,248,255,.94);display:grid;place-items:center;padding:24px}
.webgl-fallback[hidden]{display:none}
.fallback-card{max-width:520px;background:#fff;border-radius:20px;padding:28px;box-shadow:var(--shadow)}
.fallback-card h2{margin:0 0 10px;font-size:24px}
.fallback-card p{font-size:13px;line-height:1.8;color:#3d5570}

@media (max-width:1200px){
  .parts-panel{display:none}
  .card{width:min(420px,94vw)}
}
@media (max-width:820px){
  .topbar{height:60px;padding:0 5vw}
  .top-meta{display:none}
  .brand-mark{width:32px;height:32px;font-size:11px;border-radius:9px}
  .brand-text{font-size:9.5px;letter-spacing:.12em}
  .brand-text em{font-size:8px}
  .nav{display:none}
  .hero{padding:96px 5vw 70px;min-height:100svh}
  .hero-inner{background:rgba(247,252,255,.9);border:1px solid rgba(255,255,255,.96);border-radius:24px;padding:24px 20px;box-shadow:0 22px 60px rgba(31,56,100,.12);backdrop-filter:blur(18px)}
  .hero h1{font-size:clamp(48px,15vw,72px)}
  .hero-sub{font-size:14px;margin:18px 0 28px}
  .hero-stats{grid-template-columns:1fr;max-width:360px}
  .stat{padding:13px 0}
  .stat + .stat{padding-left:0;border-left:0;border-top:1px solid var(--line)}
  .stat strong{font-size:22px}
  .scroll-hint{margin-top:30px;font-size:9px}
  .hero-note{display:none}
  .section{padding:100px 5vw 120px;min-height:100svh;align-items:flex-end}
  .section-inner{justify-content:center!important}
  .card{width:100%;padding:24px 21px;border-radius:20px;background:rgba(255,255,255,.86)}
  .card h2{font-size:28px}
  .card p{font-size:12.5px;line-height:1.75}
  .tokamak-intro .card,.energy-intro .card{width:100%}
  .mini-spec{grid-template-columns:1fr 1fr}
  .spec-grid{grid-template-columns:1fr 1fr}
  .part-index{left:5vw;bottom:12px;font-size:8px}
  .step-chip{right:5vw;bottom:12px;font-size:8px;padding:7px 10px}
  .parts-panel{display:none}
  .callout-line{width:26px}
  .callout-box{min-width:104px;padding:7px 9px}
  .callout-box strong{font-size:10px}
  .callout-box span{font-size:8.5px}
  .energy-ui{top:72px;left:5vw;right:5vw}
  .energy-head{display:flex;flex-direction:column;gap:4px}
  .energy-total{position:static;text-align:left;margin-top:6px}
  .energy-total strong{font-size:34px}
  .source-labels{display:none!important}
  .callout-layer{display:none!important}
  .energy-head{display:block}
  .energy-head h2{font-size:26px}
  .energy-total{text-align:left;margin-top:12px}
  .energy-total strong{font-size:38px}
  .energy-note{left:5vw;right:5vw;max-width:none;bottom:calc(4.5vh + 128px);padding:10px 12px}
  .energy-note strong{font-size:11px}
  .energy-note span{font-size:9px}
  .energy-dash{left:4vw;right:4vw;bottom:12px;padding:12px 12px 11px}
  .year-toggle{right:8px;top:-42px}
  .year-toggle button{padding:6px 12px;font-size:10px}
  .mix-legend{gap:7px 11px}
  .legend-item{font-size:9.5px}
  .source-label{min-width:92px;padding:6px 8px}
  .source-label strong{font-size:9.5px}
  .source-label b{font-size:11px}
  .source-label em{font-size:8px}
  .closing{padding-top:120px;padding-bottom:80px}
  .closing-card{width:100%}
  .closing-meta{grid-template-columns:1fr 1fr}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *{animation-duration:.001ms!important;animation-iteration-count:1!important;transition-duration:.001ms!important}
}


/* scene visibility */
.energy-ui,.energy-dash,.energy-note,.source-labels{opacity:0;visibility:hidden;transition:opacity .5s ease,visibility .5s}
body.energy.energy-flow .energy-ui,body.energy.energy-flow .energy-dash,body.energy.energy-flow .energy-note,body.energy.energy-flow .source-labels{opacity:1;visibility:visible}
.parts-panel,.part-index,.step-chip{transition:opacity .45s ease,visibility .45s}
body.energy .parts-panel,body.energy .part-index,body.energy .step-chip{opacity:0;visibility:hidden;pointer-events:none}
body.energy .callout-layer{opacity:0;visibility:hidden}