:root{
  --bg:#f5f8ff;--surface:#ffffff;--surface-2:#eef4ff;--ink:#14213d;--muted:#596985;
  --primary:#3157e8;--primary-dark:#203fae;--violet:#6948db;--mint:#e7f8f2;--mint-ink:#1f6d58;
  --navy:#13264d;--line:#dce5f4;--shadow:0 18px 50px rgba(29,52,98,.10);--shadow-soft:0 8px 24px rgba(29,52,98,.07)
}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;background:radial-gradient(circle at 85% 5%,#e8e5ff 0,transparent 28%),linear-gradient(180deg,#f8fbff 0%,var(--bg) 100%);color:var(--ink)}
a{color:inherit}.section-shell{width:min(100% - 40px,1160px);margin-inline:auto}.site-header{position:sticky;top:0;z-index:50;display:flex;justify-content:space-between;align-items:center;padding:14px max(20px,calc((100vw - 1160px)/2));background:rgba(248,251,255,.90);border-bottom:1px solid rgba(220,229,244,.9);backdrop-filter:blur(16px)}
.brand{display:flex;align-items:center;gap:12px;text-decoration:none}.brand-mark{width:46px;height:46px;border-radius:15px;display:grid;place-items:center;background:linear-gradient(135deg,var(--primary),var(--violet));color:#fff;font-weight:900;box-shadow:0 8px 20px rgba(49,87,232,.22)}.brand strong{display:block}.brand small{display:block;color:var(--muted);font-size:.78rem;margin-top:2px}.nav-links{display:flex;align-items:center;gap:24px}.nav-links a{text-decoration:none;color:#45536e;font-weight:750;font-size:.92rem}.nav-links a:hover{color:var(--primary)}.menu-toggle{display:none;border:0;background:transparent;font-size:1.35rem;color:var(--ink);cursor:pointer}
.hero{min-height:780px;display:grid;grid-template-columns:1.25fr .75fr;gap:58px;align-items:center;padding:90px 0}.eyebrow{text-transform:uppercase;letter-spacing:.13em;font-weight:900;font-size:.73rem;color:var(--primary);margin:0 0 14px}h1,h2,h3{line-height:1.08;margin-top:0}h1{font-size:clamp(3.1rem,6vw,5.7rem);letter-spacing:-.055em;margin-bottom:25px;max-width:980px}h2{font-size:clamp(2rem,4vw,3.5rem);letter-spacing:-.04em;margin-bottom:20px}h3{font-size:1.18rem;margin-bottom:10px}p{color:var(--muted);line-height:1.68}.hero-text{font-size:1.12rem;max-width:760px}.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin:30px 0}.btn{display:inline-flex;justify-content:center;align-items:center;border-radius:14px;padding:13px 19px;text-decoration:none;border:1px solid var(--primary);font-weight:850;cursor:pointer;transition:.2s}.btn.primary{background:linear-gradient(135deg,var(--primary),#536fef);color:#fff;box-shadow:0 10px 25px rgba(49,87,232,.22)}.btn.primary:hover,.btn.ghost:hover{transform:translateY(-2px)}.btn.ghost{background:rgba(255,255,255,.76);color:var(--primary);border-color:#cdd9f3}.btn.full{width:100%}.lesson-strip{display:flex;gap:10px;flex-wrap:wrap;margin-top:26px}.lesson-strip span{padding:10px 13px;border-radius:999px;background:#fff;border:1px solid var(--line);color:#52617c;font-size:.87rem;box-shadow:var(--shadow-soft)}.lesson-strip b{color:var(--primary)}
.hero-card{position:relative;background:rgba(255,255,255,.92);border:1px solid var(--line);border-radius:30px;padding:32px;box-shadow:var(--shadow);overflow:hidden}.hero-card:before{content:"ST";position:absolute;right:-8px;top:-22px;font-size:6rem;font-weight:950;color:rgba(49,87,232,.06);letter-spacing:-.08em}.card-label,.lesson-no,.example-card>span{display:inline-block;color:var(--violet);font-size:.72rem;font-weight:900;text-transform:uppercase;letter-spacing:.12em}.hero-card h2{font-size:2rem;margin-top:10px;position:relative}.formula{margin-top:22px;padding:14px 16px;border-radius:14px;background:linear-gradient(135deg,#eef3ff,#f0ebff);font-weight:900;color:var(--primary-dark)}
.learning-section{padding:110px 0}.section-heading{max-width:870px;margin-bottom:42px}.section-heading.narrow{max-width:760px}.lesson-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}.lesson-card{background:rgba(255,255,255,.88);border:1px solid var(--line);border-radius:22px;padding:24px;box-shadow:var(--shadow-soft);transition:.2s}.lesson-card:hover{transform:translateY(-3px);border-color:#b8c9ee}.lesson-card h3{margin-top:10px}.lesson-card p{font-size:.93rem;margin:.7rem 0}.lesson-card strong{color:var(--ink)}
.concept-band{background:linear-gradient(135deg,var(--navy),#1b3972);padding:100px 0;position:relative;overflow:hidden}.concept-band:after{content:"";position:absolute;width:460px;height:460px;border-radius:50%;border:1px solid rgba(255,255,255,.08);right:-150px;top:-160px;box-shadow:0 0 0 70px rgba(255,255,255,.025),0 0 0 140px rgba(255,255,255,.015)}.section-heading.light{position:relative;z-index:2}.section-heading.light h2{color:#fff}.concept-band .eyebrow{color:#9fb9ff}.example-grid{position:relative;z-index:2;display:grid;grid-template-columns:repeat(2,1fr);gap:16px}.example-card{background:rgba(255,255,255,.07);border:1px solid rgba(255,255,255,.13);border-radius:22px;padding:25px}.example-card>span{color:#b6c7ff}.example-card h3{color:#fff;margin-top:18px;margin-bottom:6px}.example-card p{color:#cad7ef;margin-top:0}
.practice-section{padding:110px 0}.practice-layout{display:grid;grid-template-columns:.8fr 1.2fr;gap:30px}.five-test{display:grid;gap:12px}.five-test>div{display:grid;grid-template-columns:auto 1fr;gap:14px;align-items:start;background:rgba(255,255,255,.80);border:1px solid var(--line);padding:17px;border-radius:18px}.five-test span{width:37px;height:37px;display:grid;place-items:center;border-radius:12px;background:#e8eeff;color:var(--primary-dark);font-weight:950}.five-test p{margin:5px 0 0}.decision-lab{background:#fff;border:1px solid var(--line);border-radius:26px;padding:28px;box-shadow:var(--shadow)}.decision-lab>label{display:block;font-weight:850;margin-bottom:8px}.decision-lab input[type="text"]{width:100%;padding:14px 16px;border:1px solid #cbd8ee;border-radius:14px;outline:none;margin-bottom:18px}.decision-lab input[type="text"]:focus{border-color:var(--primary);box-shadow:0 0 0 4px rgba(49,87,232,.10)}.question-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:18px}.question-grid label{display:flex;align-items:flex-start;gap:9px;padding:13px;border-radius:14px;background:#f8faff;border:1px solid #e1e8f4;color:#495974;font-size:.92rem}.question-grid input{margin-top:3px;accent-color:var(--primary)}.result-box{margin-top:14px;padding:14px 16px;border-radius:14px;background:var(--mint);border:1px solid #cceee3;color:var(--mint-ink);font-weight:750;line-height:1.55}
.scenario-section{padding:0 0 110px}.scenario-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px}.scenario-grid details{background:#fff;border:1px solid var(--line);border-radius:18px;padding:18px 20px;box-shadow:var(--shadow-soft)}.scenario-grid summary{cursor:pointer;font-weight:850;color:var(--ink);line-height:1.4}.scenario-grid details[open]{border-color:#b8c9ee}.scenario-grid p{margin-bottom:0}
.quiz-band{background:linear-gradient(180deg,#edf3ff 0%,#edf9f5 100%);padding:100px 0;border-top:1px solid #dbe5f5;border-bottom:1px solid #d9ece7}.quiz-layout{display:grid;grid-template-columns:.75fr 1.25fr;gap:50px;align-items:start}.quiz-card{background:#fff;border:1px solid var(--line);border-radius:26px;padding:28px;box-shadow:var(--shadow)}fieldset{border:0;padding:0;margin:0 0 25px}legend{font-weight:900;margin-bottom:10px;line-height:1.4}.quiz-card label{display:flex;gap:10px;align-items:flex-start;padding:10px 0;color:#53627d}.quiz-card input{margin-top:4px;accent-color:var(--primary)}
.final-section{text-align:center;max-width:900px;padding:100px 0 120px}.final-section p{font-size:1.07rem}.final-section .btn{margin-top:10px}footer{background:#edf3ff;border-top:1px solid var(--line);padding:34px 0}.footer-inner{display:flex;justify-content:space-between;gap:40px;align-items:flex-start}.footer-inner p{margin:.2rem 0}.disclaimer{max-width:650px;font-size:.86rem}.back-to-top{position:fixed;right:22px;bottom:22px;width:48px;height:48px;border-radius:15px;display:grid;place-items:center;background:var(--navy);color:#fff;text-decoration:none;font-size:1.25rem;font-weight:900;box-shadow:0 14px 32px rgba(20,35,66,.22);z-index:40;opacity:0;pointer-events:none;transform:translateY(8px);transition:.2s}.back-to-top.visible{opacity:1;pointer-events:auto;transform:translateY(0)}.back-to-top:hover{background:var(--primary)}
@media(max-width:950px){.nav-links{display:none;position:absolute;top:73px;left:18px;right:18px;background:#fff;padding:18px;border:1px solid var(--line);border-radius:18px;box-shadow:var(--shadow);flex-direction:column;align-items:flex-start}.nav-links.open{display:flex}.menu-toggle{display:block}.hero,.practice-layout,.quiz-layout{grid-template-columns:1fr}.hero{min-height:auto;padding-top:65px}.lesson-grid{grid-template-columns:1fr 1fr}.example-grid,.scenario-grid{grid-template-columns:1fr}.hero-card{max-width:680px}.section-shell{width:min(100% - 28px,1160px)}}
@media(max-width:620px){h1{font-size:3rem}.hero{padding:55px 0}.learning-section,.concept-band,.practice-section,.quiz-band,.final-section{padding-top:75px;padding-bottom:75px}.lesson-grid,.question-grid{grid-template-columns:1fr}.lesson-strip{display:grid;grid-template-columns:1fr 1fr}.brand small{display:none}.footer-inner{flex-direction:column}.back-to-top{right:14px;bottom:14px}}