/* ── AI-CAD · cad.tonwork.fun ─────────────────────────────── */
:root{
  --bg:#0b0f14;
  --bg-2:#0e141b;
  --panel:#131b24;
  --panel-2:#18222d;
  --line:#22303f;
  --line-soft:#1a2531;
  --fg:#e6edf3;
  --fg-2:#9fb0c0;
  --fg-3:#6d8091;
  --accent:#4fd1c5;
  --accent-2:#3aa8e0;
  --warn:#e0a33a;
  --radius:14px;
  --wrap:1180px;
  --sans:-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans CJK SC",sans-serif;
  --mono:ui-monospace,SFMono-Regular,"SF Mono",Menlo,Consolas,monospace;
}

*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:76px}
body{
  margin:0;background:var(--bg);color:var(--fg);
  font-family:var(--sans);font-size:16px;line-height:1.7;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
}
img{max-width:100%;display:block;height:auto}
a{color:inherit;text-decoration:none}
h1,h2,h3{line-height:1.25;margin:0;letter-spacing:-.01em}
p{margin:0}
code{font-family:var(--mono);font-size:.88em;background:#1b2733;border:1px solid var(--line);border-radius:5px;padding:.1em .4em}
.wrap{width:100%;max-width:var(--wrap);margin:0 auto;padding:0 24px}

/* ── nav ── */
.nav{position:sticky;top:0;z-index:50;background:rgba(11,15,20,.72);backdrop-filter:blur(14px);border-bottom:1px solid transparent;transition:border-color .25s,background .25s}
.nav.is-stuck{border-bottom-color:var(--line-soft);background:rgba(11,15,20,.92)}
.nav-inner{display:flex;align-items:center;gap:26px;height:64px}
.brand{display:flex;align-items:center;gap:9px;font-weight:700;letter-spacing:.02em;color:var(--accent);flex:none}
.brand svg{display:block}
.nav-links{display:flex;gap:22px;margin-left:auto;font-size:14.5px;color:var(--fg-2)}
.nav-links a{transition:color .18s}
.nav-links a:hover{color:var(--fg)}
.btn{
  display:inline-flex;align-items:center;justify-content:center;
  padding:11px 22px;border-radius:10px;font-size:15px;font-weight:600;
  background:linear-gradient(180deg,var(--accent),#35b3a8);color:#04231f;
  border:1px solid rgba(79,209,197,.5);transition:transform .15s,box-shadow .2s,background .2s;
}
.btn:hover{transform:translateY(-1px);box-shadow:0 8px 26px rgba(79,209,197,.22)}
.btn-sm{padding:8px 16px;font-size:14px}
.btn-ghost{background:transparent;color:var(--fg);border-color:var(--line)}
.btn-ghost:hover{border-color:#33475c;box-shadow:none;background:#131c26}

/* ── hero ── */
.hero{position:relative;overflow:hidden;padding:78px 0 84px;border-bottom:1px solid var(--line-soft)}
.hero-glow{position:absolute;inset:-30% -10% auto -10%;height:620px;pointer-events:none;
  background:radial-gradient(46% 60% at 22% 40%,rgba(79,209,197,.16),transparent 68%),
             radial-gradient(40% 55% at 78% 22%,rgba(58,168,224,.13),transparent 70%);}
.hero-grid{position:relative;display:grid;grid-template-columns:1fr 1.02fr;gap:54px;align-items:center}
.eyebrow{font-family:var(--mono);font-size:12.5px;letter-spacing:.1em;text-transform:uppercase;color:var(--accent);margin-bottom:18px}
.hero h1{font-size:52px;font-weight:750;letter-spacing:-.025em;margin-bottom:22px}
.hero h1 em{font-style:normal;background:linear-gradient(96deg,var(--accent),var(--accent-2));-webkit-background-clip:text;background-clip:text;color:transparent}
.lede{font-size:17px;color:var(--fg-2);max-width:36em}
.hero-actions{display:flex;gap:12px;margin-top:30px;flex-wrap:wrap}
.hero-facts{list-style:none;display:flex;gap:34px;margin:40px 0 0;padding:22px 0 0;border-top:1px solid var(--line-soft);flex-wrap:wrap}
.hero-facts li{display:flex;flex-direction:column;gap:2px}
.hero-facts b{font-size:26px;font-weight:700;font-variant-numeric:tabular-nums;letter-spacing:-.02em}
.hero-facts span{font-size:12.5px;color:var(--fg-3)}
.hero-visual{margin:0}
.hero-visual img{border-radius:var(--radius);border:1px solid var(--line);background:#e9eef2}
.hero-visual figcaption{margin-top:12px;font-size:13px;color:var(--fg-3);font-family:var(--mono)}

/* ── sections ── */
.sec{padding:84px 0;border-bottom:1px solid var(--line-soft)}
.sec-alt{background:var(--bg-2)}
.sec-head{max-width:60ch;margin-bottom:44px}
.sec-head h2{font-size:32px;font-weight:700;margin-bottom:12px}
.sec-head p{color:var(--fg-2);font-size:16.5px}
.sub{font-size:17px;font-weight:650;margin-bottom:16px}
.note{margin-top:14px;font-size:13.5px;color:var(--fg-3)}

/* ── cards ── */
.cards{display:grid;gap:18px}
.c2{grid-template-columns:repeat(2,1fr)}
.c3{grid-template-columns:repeat(3,1fr)}
.c4{grid-template-columns:repeat(4,1fr)}
.card{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:24px}
.card h3{font-size:16.5px;font-weight:650;margin-bottom:10px}
.card p{font-size:14.5px;color:var(--fg-2)}
.card .num{display:block;font-family:var(--mono);font-size:12px;color:var(--accent);letter-spacing:.08em;margin-bottom:12px}
.card-k{padding:26px 24px}
.card-k h3{color:var(--fg)}
.card-warn{border-color:#3a3320;background:linear-gradient(180deg,#161510,#131b24)}
.card-warn h3{color:var(--warn)}

.kpi{list-style:none;margin:16px 0 0;padding:16px 0 0;border-top:1px solid var(--line-soft);display:flex;flex-direction:column;gap:8px}
.kpi li{font-size:13.5px;color:var(--fg-2);padding-left:16px;position:relative}
.kpi li::before{content:"";position:absolute;left:0;top:.62em;width:6px;height:6px;border-radius:2px;background:var(--accent)}
.kpi b{color:var(--fg);font-variant-numeric:tabular-nums}

.ticks{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:9px}
.ticks li{font-size:14.5px;color:var(--fg-2);padding-left:22px;position:relative}
.ticks li::before{content:"";position:absolute;left:1px;top:.55em;width:5px;height:9px;
  border:solid var(--accent);border-width:0 1.7px 1.7px 0;transform:rotate(45deg);opacity:.85}
.ticks b{color:var(--fg)}

/* ── tables ── */
.table-block{margin-top:44px}
.tbl-scroll{overflow-x:auto;border:1px solid var(--line);border-radius:var(--radius);background:var(--panel)}
table{width:100%;border-collapse:collapse;font-size:14.5px;min-width:560px}
thead th{
  text-align:left;font-weight:600;font-size:12.5px;letter-spacing:.05em;text-transform:uppercase;
  color:var(--fg-3);padding:13px 18px;border-bottom:1px solid var(--line);background:#101821;white-space:nowrap;
}
tbody td{padding:14px 18px;border-bottom:1px solid var(--line-soft);color:var(--fg-2);vertical-align:top}
tbody tr:last-child td{border-bottom:none}
tbody td:first-child{color:var(--fg);font-weight:550}
tbody tr:hover td{background:#151f29}

.evidence{margin-top:48px}
.split{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin-top:48px}
.panel{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:26px}
.panel > p{font-size:14.5px;color:var(--fg-2);margin-bottom:16px}

/* ── steps ── */
.steps{list-style:none;margin:0 0 8px;padding:0;display:grid;grid-template-columns:repeat(4,1fr);gap:18px;counter-reset:s}
.steps li{position:relative;background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:24px}
.steps li::after{content:"";position:absolute;top:34px;right:-19px;width:19px;height:1px;background:var(--line)}
.steps li:last-child::after{display:none}
.s-num{display:inline-block;font-family:var(--mono);font-size:12px;color:var(--accent);letter-spacing:.08em;margin-bottom:12px}
.steps h3{font-size:16px;margin-bottom:8px}
.steps p{font-size:14px;color:var(--fg-2)}

/* ── timeline ── */
.timeline{list-style:none;margin:0;padding:0 0 0 26px;position:relative}
.timeline::before{content:"";position:absolute;left:5px;top:8px;bottom:8px;width:1px;background:var(--line)}
.timeline li{position:relative;padding:0 0 30px 24px}
.timeline li:last-child{padding-bottom:0}
.timeline li::before{content:"";position:absolute;left:-26px;top:.55em;width:11px;height:11px;border-radius:50%;
  background:var(--bg-2);border:2px solid var(--accent)}
.t-when{display:inline-block;font-family:var(--mono);font-size:12px;color:var(--accent);background:#132029;
  border:1px solid var(--line);border-radius:6px;padding:2px 9px;margin-bottom:10px}
.timeline h3{font-size:16.5px;margin-bottom:6px}
.timeline p{font-size:14.5px;color:var(--fg-2)}

.roi{margin-top:48px;background:linear-gradient(120deg,#121b24,#101821);border:1px solid var(--line);
  border-radius:var(--radius);padding:28px;display:grid;grid-template-columns:1.1fr 1fr;gap:30px}
.formula{font-family:var(--mono);font-size:14.5px;color:var(--accent);line-height:1.9}

/* ── 3D viewer ── */
.viewer-shell{border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;background:var(--panel)}
.viewer-bar{display:flex;align-items:center;gap:20px;padding:14px 18px;border-bottom:1px solid var(--line);background:#101821;flex-wrap:wrap}
.seg{display:inline-flex;background:#0b1219;border:1px solid var(--line);border-radius:9px;padding:3px;gap:2px}
.seg-btn{appearance:none;border:0;background:transparent;color:var(--fg-2);font-family:inherit;font-size:13.5px;
  font-weight:550;padding:7px 14px;border-radius:7px;cursor:pointer;transition:background .16s,color .16s}
.seg-btn:hover{color:var(--fg)}
.seg-btn.is-on{background:#1c2a36;color:var(--accent);box-shadow:inset 0 0 0 1px rgba(79,209,197,.25)}
.viewer-meta{margin-left:auto;display:flex;flex-direction:column;align-items:flex-end;gap:1px;text-align:right}
#v-title{font-size:14px;font-weight:600}
#v-size{font-size:12px;color:var(--fg-3);font-family:var(--mono)}
.stage{position:relative;height:min(66vh,640px);background:#0d131a;
  background-image:linear-gradient(rgba(255,255,255,.032) 1px,transparent 1px),linear-gradient(90deg,rgba(255,255,255,.032) 1px,transparent 1px);
  background-size:44px 44px}
#scene{width:100%;height:100%;display:block;cursor:grab}
#scene:active{cursor:grabbing}
.stage-hint{position:absolute;left:16px;top:14px;font-size:12.5px;color:var(--fg-3);font-family:var(--mono);pointer-events:none}
.stage-load{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;gap:10px;
  background:rgba(13,19,26,.82);font-size:14px;color:var(--fg-2);transition:opacity .3s}
.stage-load[hidden]{display:none}
.spin{width:15px;height:15px;border-radius:50%;border:2px solid var(--line);border-top-color:var(--accent);animation:sp .8s linear infinite}
@keyframes sp{to{transform:rotate(360deg)}}
.stage-legend{position:absolute;left:16px;bottom:14px;display:flex;flex-wrap:wrap;gap:14px;font-size:12px;color:var(--fg-3);pointer-events:none}
.stage-legend span{display:inline-flex;align-items:center;gap:6px}
.stage-legend i{width:11px;height:3px;border-radius:2px;display:block}

.gal{display:grid;grid-template-columns:repeat(3,1fr);gap:18px;margin-top:22px}
.gal figure{margin:0}
.gal img{border-radius:var(--radius);border:1px solid var(--line);background:#e9eef2}
.gal figcaption{margin-top:10px;font-size:12.5px;color:var(--fg-3);font-family:var(--mono)}

/* ── CTA ── */
.cta{padding:76px 0;background:
  radial-gradient(60% 120% at 15% 0%,rgba(79,209,197,.13),transparent 65%),var(--bg)}
.cta-inner{display:flex;align-items:center;justify-content:space-between;gap:36px;flex-wrap:wrap}
.cta h2{font-size:30px;margin-bottom:10px}
.cta p{color:var(--fg-2);max-width:46ch}
.cta-actions{display:flex;gap:12px;flex-wrap:wrap}

/* ── foot ── */
.foot{border-top:1px solid var(--line-soft);padding:36px 0;background:#090d12}
.foot-inner{display:flex;align-items:center;gap:28px;flex-wrap:wrap;font-size:13.5px;color:var(--fg-3)}
.foot-brand{display:flex;flex-direction:column;gap:2px}
.foot-brand strong{color:var(--accent);font-size:15px;letter-spacing:.02em}
.foot-links{display:flex;gap:20px;margin-left:auto}
.foot-links a:hover{color:var(--fg)}
.foot-meta{display:flex;flex-direction:column;align-items:flex-end;gap:2px;font-family:var(--mono);font-size:12px}

/* ── responsive ── */
@media (max-width:1080px){
  .hero h1{font-size:44px}
  .c4{grid-template-columns:repeat(2,1fr)}
  .c3{grid-template-columns:repeat(2,1fr)}
  .steps{grid-template-columns:repeat(2,1fr)}
  .steps li:nth-child(2)::after{display:none}
}
@media (max-width:860px){
  .nav-links{display:none}
  .hero{padding:52px 0 60px}
  .hero-grid{grid-template-columns:1fr;gap:36px}
  .hero h1{font-size:36px}
  .hero-facts{gap:24px}
  .sec{padding:60px 0}
  .sec-head h2{font-size:26px}
  .c2,.c3,.c4,.steps,.split,.roi,.gal{grid-template-columns:1fr}
  .steps li::after{display:none}
  .viewer-meta{align-items:flex-start;text-align:left;margin-left:0}
  .stage{height:52vh}
  .stage-legend{display:none}
  .foot-inner{flex-direction:column;align-items:flex-start}
  .foot-links{margin-left:0}
  .foot-meta{align-items:flex-start}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *{animation-duration:.01ms!important;transition-duration:.01ms!important}
}