:root{--bg:#f6f8fb;--paper:#fff;--ink:#161214;--muted:#6e5f64;--line:#dfe6ef;--brand:#22181c;--accent:#b8541a;--soft:#eef8fa;--bad:#fff1f0;--good:#e8f7ef}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.55 Inter,system-ui,-apple-system,Segoe UI,sans-serif}a{color:inherit}.wrap{width:min(1180px,calc(100% - 32px));margin:auto}.site-header{position:sticky;top:0;z-index:5;background:#fff;border-bottom:1px solid var(--line)}.header-inner{min-height:66px;display:flex;align-items:center;justify-content:space-between;gap:16px}.brand{display:flex;gap:10px;align-items:center;text-decoration:none}.brand-mark{width:38px;height:38px;border-radius:10px;background:var(--brand);display:grid;place-items:center;color:#fff;font-weight:900}.brand-name{font-weight:850;display:block}.brand-sub{font-size:.7rem;color:var(--muted);display:block}.back{padding:8px 12px;border:1px solid var(--line);border-radius:999px;text-decoration:none;font-size:.8rem;font-weight:700}.hero{padding:36px 0 22px}.crumbs{font-size:.8rem;color:var(--muted);margin-bottom:14px}.kicker{color:var(--accent);font-weight:800;text-transform:uppercase;letter-spacing:.1em;font-size:.75rem}.hero h1{font-size:clamp(2rem,4vw,3.2rem);line-height:1.1;margin:10px 0}.lead{max-width:900px;color:#6e5f64}.badges{display:flex;gap:8px;flex-wrap:wrap}.badge{padding:5px 10px;border:1px solid #cfe1e6;border-radius:999px;background:#fff;color:var(--accent);font-size:.75rem;font-weight:800}.tabs{display:flex;gap:8px;flex-wrap:wrap;margin:16px 0}.tab{border:1px solid var(--line);background:#fff;color:var(--brand);border-radius:10px;padding:10px 13px;font-weight:800;cursor:pointer}.tab.active,.tab:hover{background:var(--accent);color:#fff;border-color:var(--accent)}.panel{display:none}.panel.active{display:block}.study-grid{display:grid;gap:18px}.card,.subcard,.question,.comparison{background:#fff;border:1px solid var(--line);border-radius:16px;padding:20px;box-shadow:0 2px 10px #22181c08}.card h2{font-size:1.3rem;margin:0 0 14px}.card h3,.subcard h3{margin:0 0 8px}.card p,.subcard p{color:#6e5f64}.card ul,.subcard ul{padding-left:21px}.card li{margin:7px 0}.scope-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px}.scope-grid>div{background:var(--soft);padding:15px;border-radius:12px}.scope-grid p{margin:0}.subcard{margin:12px 0;background:#fbfcfe}.result{border-left:4px solid var(--accent);padding-left:12px}.level{display:inline-block;color:var(--accent);font-size:.72rem;font-weight:900;text-transform:uppercase;letter-spacing:.08em;margin-bottom:6px}.table-wrap{overflow:auto}table{width:100%;border-collapse:collapse;min-width:680px}th,td{text-align:left;vertical-align:top;padding:10px;border:1px solid var(--line)}th{background:#f0f5f8}.equation{font-size:1.05rem}.glossary{display:grid;gap:8px}.glossary div{display:grid;grid-template-columns:180px 1fr;gap:12px;border-bottom:1px solid var(--line);padding:8px 0}.question{margin:14px 0}.question h3{margin:0 0 12px;font-size:1rem}.options{display:grid;gap:8px}.option{padding:10px 12px;text-align:left;background:#fff;border:1px solid var(--line);border-radius:9px;cursor:pointer}.option:hover{border-color:var(--accent)}.option.correct{background:var(--good);border-color:#b45309}.option.incorrect{background:var(--bad);border-color:#dc6b64}.answer{display:none;color:#6e5f64;margin:12px 0 0}.question.answered .answer{display:block}.related{display:flex;gap:8px;flex-wrap:wrap;margin:16px 0 50px}.related a{padding:7px 10px;background:#fff;border:1px solid var(--line);border-radius:8px;text-decoration:none;font-size:.8rem}.footer{padding:28px 0;background:#fff;border-top:1px solid var(--line);color:var(--muted);font-size:.8rem}@media(max-width:680px){.scope-grid,.glossary div{grid-template-columns:1fr}.header-inner{align-items:flex-start;padding:12px 0;flex-direction:column}}