:root{--bg:#f6f7fb;--panel:#fff;--ink:#172033;--muted:#657087;--line:#dfe4ec;--accent:#3d4fb5;--accent2:#eef0ff;--good:#1f7a57;--warn:#a45b12;--shadow:0 10px 30px rgba(23,32,51,.08)}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;line-height:1.6}a{color:inherit;text-decoration:none}.shell{max-width:1180px;margin:auto;padding:20px}.top{position:sticky;top:0;z-index:10;background:rgba(246,247,251,.94);backdrop-filter:blur(12px);border-bottom:1px solid var(--line)}.nav{max-width:1180px;margin:auto;display:flex;align-items:center;justify-content:space-between;gap:16px;padding:14px 20px}.brand{font-weight:800;letter-spacing:-.02em}.brand small{display:block;color:var(--muted);font-weight:500;font-size:.72rem}.links{display:flex;gap:14px;flex-wrap:wrap}.links a{padding:7px 9px;color:var(--muted);font-weight:650}.links a:hover{color:var(--ink)}.hero{padding:55px 0 25px}.eyebrow{display:inline-block;font-size:.75rem;text-transform:uppercase;letter-spacing:.12em;font-weight:800;color:var(--accent);margin-bottom:10px}.hero h1{font-size:clamp(2rem,5vw,4rem);line-height:1.03;margin:0 0 16px;max-width:850px;letter-spacing:-.04em}.hero p{font-size:1.08rem;color:var(--muted);max-width:760px}.actions{display:flex;gap:10px;flex-wrap:wrap;margin:22px 0}.button{display:inline-flex;align-items:center;justify-content:center;padding:10px 15px;border-radius:10px;background:var(--accent);color:white;font-weight:750;border:1px solid var(--accent);cursor:pointer}.button.secondary{background:var(--panel);color:var(--ink);border-color:var(--line)}.grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:16px}.grid.two{grid-template-columns:repeat(2,minmax(0,1fr))}.card{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:20px;box-shadow:var(--shadow)}.card h2,.card h3{line-height:1.2;margin-top:0}.muted{color:var(--muted)}.tag{display:inline-flex;padding:4px 8px;border-radius:999px;background:var(--accent2);color:var(--accent);font-size:.75rem;font-weight:750;margin:3px}.stat{font-size:2rem;font-weight:850}.section{margin:34px 0}.section h2{letter-spacing:-.02em}.search{width:100%;padding:13px 15px;border:1px solid var(--line);border-radius:12px;font:inherit;background:#fff}.list{display:grid;gap:12px;margin-top:14px}.list-item{display:block;background:#fff;border:1px solid var(--line);padding:16px;border-radius:13px}.list-item:hover{border-color:#aeb8da;box-shadow:0 6px 20px rgba(23,32,51,.06)}.split{display:grid;grid-template-columns:260px 1fr;gap:20px}.side{position:sticky;top:82px;align-self:start}.toc a{display:block;padding:7px 0;color:var(--muted)}.toc a:hover{color:var(--accent)}.content h2{margin-top:30px}.callout{border-left:4px solid var(--accent);background:var(--accent2);padding:15px 17px;border-radius:0 10px 10px 0}.quiz-option{display:block;width:100%;text-align:left;border:1px solid var(--line);background:#fff;border-radius:11px;padding:12px;margin:9px 0;cursor:pointer}.quiz-option:hover{border-color:#9ba7d4}.quiz-option.correct{border-color:#78b99d;background:#eef9f4}.quiz-option.wrong{border-color:#d49b7d;background:#fff4ef}.progress{height:8px;background:#e7eaf1;border-radius:999px;overflow:hidden}.progress span{display:block;height:100%;background:var(--accent)}footer{margin-top:60px;padding:28px 0;color:var(--muted);font-size:.9rem;border-top:1px solid var(--line)}@media(max-width:800px){.grid,.grid.two{grid-template-columns:1fr}.split{grid-template-columns:1fr}.side{position:static}.links{display:none}.hero{padding-top:35px}.shell{padding:15px}}