:root{
  --bg:#0c0e16; --bg-soft:#12151f; --card:#161a26; --card-2:#1c2030;
  --line:#262b3d; --ink:#eef1f8; --muted:#9aa3bd;
  --brand:#6c8cff; --brand-2:#9a6cff; --accent:#36e3b0; --warn:#ffcb6b; --bad:#ff8b8b;
  --radius:18px; --maxw:1120px; --shadow:0 20px 60px rgba(0,0,0,.45);
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  background:radial-gradient(1200px 700px at 80% -10%, rgba(108,140,255,.16), transparent 60%),
             radial-gradient(900px 600px at -10% 10%, rgba(154,108,255,.12), transparent 55%), var(--bg);
  color:var(--ink); line-height:1.55;
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Inter,Roboto,Helvetica,Arial,sans-serif;
  -webkit-font-smoothing:antialiased;
}
a{color:inherit;text-decoration:none}
em{color:var(--ink);font-style:italic}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 22px}
.narrow{max-width:820px}
.pill{display:inline-flex;align-items:center;gap:8px;font-size:13px;font-weight:600;color:var(--muted);
  border:1px solid var(--line);background:var(--bg-soft);padding:7px 13px;border-radius:999px}
.dot{width:8px;height:8px;border-radius:50%;background:var(--accent);box-shadow:0 0 12px var(--accent)}

header.nav{position:sticky;top:0;z-index:50;backdrop-filter:blur(12px);
  background:rgba(12,14,22,.72);border-bottom:1px solid var(--line)}
.nav-in{display:flex;align-items:center;justify-content:space-between;height:64px}
.logo{display:flex;align-items:center;gap:10px;font-weight:800;letter-spacing:-.3px;font-size:18px}
.logo .mark{width:30px;height:30px;border-radius:9px;background:linear-gradient(135deg,var(--brand),var(--brand-2));
  display:grid;place-items:center;font-size:16px}
nav.links{display:flex;gap:24px;font-size:14px;color:var(--muted);font-weight:500}
nav.links a:hover{color:var(--ink)}
.btn{display:inline-flex;align-items:center;gap:8px;font-weight:700;font-size:14px;padding:11px 18px;
  border-radius:12px;border:1px solid transparent;cursor:pointer;transition:.18s}
.btn-primary{background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff}
.btn-primary:hover{transform:translateY(-1px);box-shadow:0 10px 26px rgba(108,140,255,.4)}
.btn-ghost{border-color:var(--line);color:var(--ink);background:var(--bg-soft)}
.btn-ghost:hover{border-color:var(--brand)}
.btn-sm{padding:8px 13px;font-size:13px}
@media(max-width:820px){nav.links{display:none}}

.hero{padding:84px 0 52px}
.hero h1{font-size:clamp(34px,6vw,60px);line-height:1.05;letter-spacing:-1.5px;font-weight:850;max-width:16ch}
.hero h1 .grad{background:linear-gradient(120deg,var(--brand),var(--accent) 70%);-webkit-background-clip:text;background-clip:text;color:transparent}
.hero p.sub{margin-top:22px;font-size:clamp(16px,2.2vw,20px);color:var(--muted);max-width:58ch}
.hero .cta{margin-top:34px;display:flex;gap:14px;flex-wrap:wrap;align-items:center}
.meta-row{margin-top:40px;display:flex;gap:34px;flex-wrap:wrap}
.meta-row .stat b{font-size:26px;font-weight:800;letter-spacing:-.5px;display:block}
.meta-row .stat span{font-size:13px;color:var(--muted)}

section{padding:62px 0}
.eyebrow{color:var(--brand);font-weight:700;font-size:13px;letter-spacing:.12em;text-transform:uppercase}
.h2{font-size:clamp(26px,4vw,40px);font-weight:820;letter-spacing:-.8px;margin-top:10px}
.lead{color:var(--muted);max-width:64ch;margin-top:14px;font-size:17px}

.quoteband{border-top:1px solid var(--line);border-bottom:1px solid var(--line);
  background:linear-gradient(180deg,rgba(108,140,255,.06),transparent)}
.quoteband .wrap{padding:46px 22px;text-align:center}
.quoteband q{font-size:clamp(20px,3.4vw,30px);font-weight:800;letter-spacing:-.5px;quotes:none}
.quoteband q .grad{background:linear-gradient(120deg,var(--accent),var(--brand));-webkit-background-clip:text;background-clip:text;color:transparent}
.quoteband .by{margin-top:12px;color:var(--muted);font-size:14px;font-weight:600}

.myth{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin-top:38px}
@media(max-width:720px){.myth{grid-template-columns:1fr}}
.panel{border:1px solid var(--line);border-radius:var(--radius);padding:26px}
.panel.bad{background:linear-gradient(180deg,rgba(255,107,107,.08),transparent)}
.panel.good{background:linear-gradient(180deg,rgba(54,227,176,.09),transparent)}
.panel h3{font-size:15px;text-transform:uppercase;letter-spacing:.08em;font-weight:800}
.panel.bad h3{color:var(--bad)}.panel.good h3{color:var(--accent)}
.panel ul{list-style:none;margin-top:14px;display:flex;flex-direction:column;gap:11px}
.panel li{display:flex;gap:10px;font-size:15px;color:var(--muted)}
.panel li b{color:var(--ink)}

.hier{display:flex;flex-direction:column;gap:14px;margin-top:36px}
.tier{display:grid;grid-template-columns:120px 1fr;gap:20px;align-items:center;
  border:1px solid var(--line);border-radius:16px;padding:20px 22px;background:var(--card)}
.tier .ord{font-size:13px;font-weight:800;color:var(--brand);text-transform:uppercase;letter-spacing:.08em}
.tier h3{font-size:20px;font-weight:800;letter-spacing:-.4px}
.tier p{color:var(--muted);font-size:14.5px;margin-top:3px}
.tier.apply{background:var(--bg-soft);border-style:dashed}
.tier .badge,.frame .badge{display:inline-block;font-size:11px;font-weight:800;color:var(--accent);border:1px solid var(--line);
  padding:3px 9px;border-radius:999px;margin-left:8px;vertical-align:middle}

.chapter{border:1px solid var(--line);border-radius:20px;margin-top:18px;overflow:hidden;background:var(--card)}
.ch-head{display:grid;grid-template-columns:56px 1fr auto;align-items:center;gap:18px;padding:22px 24px;
  background:linear-gradient(135deg,rgba(108,140,255,.12),rgba(154,108,255,.06))}
.ch-head .cn{width:48px;height:48px;border-radius:13px;display:grid;place-items:center;font-weight:850;font-size:20px;
  background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff}
.ch-head h3{font-size:21px;font-weight:800;letter-spacing:-.4px}
.ch-head h3 .frame{font-size:12px;font-weight:800;color:var(--accent);border:1px solid var(--line);
  padding:3px 9px;border-radius:999px;margin-left:8px;vertical-align:middle;letter-spacing:.05em}
.ch-head p{color:var(--muted);font-size:14px;margin-top:3px}
.ch-head .span{font-size:12px;font-weight:700;color:var(--accent);border:1px solid var(--line);
  padding:6px 11px;border-radius:999px;white-space:nowrap;background:var(--bg-soft)}
.lesson{display:grid;grid-template-columns:74px 1fr 18px;gap:16px;align-items:center;padding:15px 24px;border-top:1px solid var(--line);transition:.15s}
.lesson:hover{background:var(--card-2)}
.lesson:hover .arw{color:var(--brand)}
.lesson .ts{font-variant-numeric:tabular-nums;font-size:13px;font-weight:700;color:var(--brand);
  background:var(--bg-soft);border:1px solid var(--line);border-radius:8px;padding:5px 0;text-align:center}
.lesson h4{font-size:15.5px;font-weight:680}
.lesson p{color:var(--muted);font-size:13.5px;margin-top:2px}
.lesson .arw{color:var(--muted);font-weight:800}

.acros{display:grid;grid-template-columns:1fr 1fr;gap:18px;margin-top:34px}
@media(max-width:760px){.acros{grid-template-columns:1fr}}
.acro{border:1px solid var(--line);border-radius:var(--radius);padding:24px;background:var(--card)}
.acro h3{font-size:18px;font-weight:800}
.acro .tag{font-size:12px;color:var(--brand);font-weight:700}
.acro ul{list-style:none;margin-top:14px;display:flex;flex-direction:column;gap:9px}
.acro li{display:flex;gap:11px;font-size:14px;color:var(--muted)}
.acro li b{color:var(--ink);font-weight:800;min-width:96px}

.ladder{background:linear-gradient(180deg,var(--bg-soft),var(--card));border:1px solid var(--line);
  border-radius:24px;padding:34px;margin-top:30px}
.rung{display:flex;align-items:center;gap:16px;padding:12px 0;border-bottom:1px dashed var(--line)}
.rung:last-child{border-bottom:0}
.rung .lvl{font-size:11px;font-weight:800;width:96px}
.rung .lvl.lo{color:var(--bad)}.rung .lvl.hi{color:var(--accent)}
.bar{flex:1;height:12px;border-radius:999px;background:var(--bg);overflow:hidden;border:1px solid var(--line)}
.bar i{display:block;height:100%;border-radius:999px;background:linear-gradient(90deg,var(--brand),var(--accent))}
.rung .nm{width:160px;font-weight:680;font-size:14.5px}

.numbers{display:grid;grid-template-columns:repeat(4,1fr);gap:16px;margin-top:34px}
@media(max-width:760px){.numbers{grid-template-columns:1fr 1fr}}
.nbox{border:1px solid var(--line);border-radius:16px;padding:22px;background:var(--card);text-align:center}
.nbox b{font-size:30px;font-weight:850;letter-spacing:-1px;background:linear-gradient(120deg,var(--brand),var(--accent));-webkit-background-clip:text;background-clip:text;color:transparent}
.nbox span{display:block;color:var(--muted);font-size:13px;margin-top:6px}

.final{text-align:center;background:radial-gradient(700px 300px at 50% 0%,rgba(108,140,255,.2),transparent 70%);
  border:1px solid var(--line);border-radius:28px;padding:64px 24px;margin:30px 0}
.final h2{font-size:clamp(28px,5vw,46px);font-weight:850;letter-spacing:-1px}
.final p{color:var(--muted);max-width:54ch;margin:16px auto 0;font-size:17px}

footer{border-top:1px solid var(--line);padding:34px 0;color:var(--muted);font-size:13.5px}
.foot-in{display:flex;justify-content:space-between;flex-wrap:wrap;gap:14px}

/* ---------- LESSON PAGE ---------- */
.crumb{display:flex;align-items:center;gap:8px;color:var(--muted);font-size:13px;font-weight:600;margin-top:34px;flex-wrap:wrap}
.crumb a:hover{color:var(--ink)}
.lhead{padding:18px 0 8px}
.lhead .chiprow{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin-bottom:16px}
.chip{font-size:12px;font-weight:800;color:var(--brand);border:1px solid var(--line);background:var(--bg-soft);
  padding:6px 11px;border-radius:999px;letter-spacing:.04em}
.chip.acc{color:var(--accent)}
.lhead h1{font-size:clamp(28px,5vw,46px);font-weight:850;letter-spacing:-1px;line-height:1.06}
.lhead .sum{color:var(--muted);font-size:18px;margin-top:16px;max-width:70ch}
.block{margin-top:40px}
.block h2{font-size:20px;font-weight:800;letter-spacing:-.3px;display:flex;align-items:center;gap:10px}
.block h2 .bdot{width:9px;height:9px;border-radius:50%;background:var(--brand)}
.points{list-style:none;margin-top:18px;display:flex;flex-direction:column;gap:14px}
.points li{display:grid;grid-template-columns:26px 1fr;gap:8px;color:#cdd3e6;font-size:15.5px}
.points li .k{color:var(--accent);font-weight:800}
.steps{list-style:none;margin-top:18px;display:flex;flex-direction:column;gap:12px;counter-reset:s}
.steps li{display:grid;grid-template-columns:30px 1fr;gap:12px;align-items:start;color:#cdd3e6;font-size:15.5px;
  border:1px solid var(--line);border-radius:12px;padding:14px 16px;background:var(--card)}
.steps li::before{counter-increment:s;content:counter(s);width:24px;height:24px;border-radius:7px;display:grid;place-items:center;
  font-size:12px;font-weight:800;background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff}
.qcards{display:flex;flex-direction:column;gap:14px;margin-top:18px}
.qcard{border-left:3px solid var(--accent);background:var(--bg-soft);border-radius:0 12px 12px 0;padding:16px 20px}
.qcard q{font-size:17px;font-weight:700;quotes:none;font-style:italic}
.lnav{display:flex;justify-content:space-between;gap:14px;margin:48px 0 10px;flex-wrap:wrap}
.lnav a{flex:1;min-width:200px;border:1px solid var(--line);border-radius:14px;padding:16px 18px;background:var(--card);transition:.15s}
.lnav a:hover{border-color:var(--brand);transform:translateY(-2px)}
.lnav .dir{font-size:12px;color:var(--muted);font-weight:700}
.lnav .ti{font-weight:750;font-size:15px;margin-top:3px}
.lnav .nx{text-align:right}
.lnav .disabled{opacity:.35;pointer-events:none}

/* ---------- GRIND DEMO ---------- */
.grind{border:1px solid var(--line);border-radius:20px;background:var(--card);padding:22px;margin-top:22px}
.grind .gtabs{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:16px}
.grind .gtab{border:1px solid var(--line);background:var(--bg-soft);color:var(--muted);border-radius:11px;
  padding:9px 13px;font-weight:800;font-size:13px;cursor:pointer;transition:.15s;display:flex;gap:8px;align-items:center}
.grind .gtab .gl{width:22px;height:22px;border-radius:6px;display:grid;place-items:center;font-size:12px;
  background:var(--card-2);color:var(--ink)}
.grind .gtab.on{border-color:var(--brand);color:var(--ink);background:linear-gradient(135deg,rgba(108,140,255,.18),rgba(154,108,255,.1))}
.grind .gtab.on .gl{background:linear-gradient(135deg,var(--brand),var(--brand-2));color:#fff}
.grind .gstage{border:1px solid var(--line);border-radius:14px;background:var(--bg);overflow:hidden}
.grind svg{display:block;width:100%;height:auto}
.grind .gcap{display:flex;gap:12px;align-items:flex-start;margin-top:14px;color:var(--muted);font-size:14.5px}
.grind .gcap b{color:var(--ink)}
.grind .gctrl{display:flex;gap:10px;margin-top:14px;flex-wrap:wrap}
.gnode{transition:opacity .4s ease, transform .4s ease}
.gedge{transition:opacity .5s ease, stroke-dashoffset .8s ease}
.ghide{opacity:0}

/* ---------- FLASHCARD DEMO ---------- */
.fc-session{display:flex;gap:8px;margin-bottom:16px;flex-wrap:wrap}
.fc-seg{font-size:12px;font-weight:700;color:var(--muted);border:1px solid var(--line);
  background:var(--bg-soft);border-radius:999px;padding:6px 12px}
.fc-seg.on{color:var(--ink);border-color:var(--brand);background:linear-gradient(135deg,rgba(108,140,255,.18),rgba(154,108,255,.1))}
.fc-card{background:linear-gradient(135deg,var(--card-2),var(--bg-soft));border:1px solid var(--line);
  border-radius:16px;padding:26px;min-height:160px;cursor:pointer;user-select:none;display:flex;flex-direction:column;gap:12px;transition:.15s}
.fc-card:hover{border-color:var(--brand)}
.fc-side{font-size:12px;font-weight:800;letter-spacing:.06em;color:var(--brand);text-transform:uppercase}
.fc-side.ans{color:var(--accent)}
.fc-text{font-size:20px;font-weight:750;line-height:1.35}
.fc-flag .flag{display:inline-block;font-size:12.5px;font-weight:800;border-radius:999px;padding:6px 12px;border:1px solid var(--line)}
.fc-flag .flag.up{color:var(--accent);background:rgba(54,227,176,.1)}
.fc-flag .flag.down{color:var(--warn);background:rgba(255,203,107,.1)}
.fc-rate{display:flex;gap:10px;margin-top:14px}
.fc-rate .fc-btn{flex:1;border-radius:11px;border:1px solid var(--line);background:var(--bg-soft);
  color:var(--ink);padding:12px;font-weight:800;font-size:13px;cursor:pointer;transition:.15s}
.fc-rate .fc-btn:hover{transform:translateY(-2px);border-color:var(--brand)}
.fc-rate .again{color:var(--bad)}.fc-rate .hard{color:var(--warn)}
.fc-rate .good{color:var(--accent)}.fc-rate .easy{color:var(--brand)}