:root{--bg:#f7f8fc;--surface:#fff;--text:#1c2033;--muted:#5d6480;--brand:#4f46e5;--brand-soft:#eef0ff;--border:#e3e6f0}@media (prefers-color-scheme:dark){:root{--bg:#0f1220;--surface:#171b2e;--text:#e8eaf6;--muted:#9aa1c2;--brand:#8b86ff;--brand-soft:#23284a;--border:#2a3050}}*{box-sizing:border-box;margin:0;padding:0}body{font-family:system-ui,-apple-system,Segoe UI,sans-serif;background:var(--bg);color:var(--text);line-height:1.6}a{color:inherit;text-decoration:none}.container{max-width:1000px;margin:0 auto;padding:32px 20px 64px;min-height:70vh}.nav{position:-webkit-sticky;position:sticky;top:0;z-index:10;background:var(--surface);border-bottom:1px solid var(--border)}.nav-inner{max-width:1000px;margin:0 auto;padding:12px 20px;display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:8px}.brand{font-size:1.4rem;font-weight:800}.brand span{color:var(--brand)}.links{display:flex;gap:6px;flex-wrap:wrap}.links a{padding:8px 14px;border-radius:999px;font-weight:600;color:var(--muted)}.links a:hover{background:var(--brand-soft);color:var(--brand)}.links a.active{background:var(--brand);color:#fff}.burger{display:none;background:none;border:1px solid var(--border);color:var(--text);font-size:1.2rem;padding:4px 12px;border-radius:8px;cursor:pointer}.hero{text-align:center;padding:56px 0 40px}.hero h1{font-size:clamp(2.4rem,7vw,4rem);font-weight:800}.hero h1 span{color:var(--brand)}.hero p{color:var(--muted);max-width:520px;margin:12px auto 24px;font-size:1.1rem}.btn{display:inline-block;background:var(--brand);color:#fff;padding:12px 24px;border-radius:12px;font-weight:700}.btn:hover{opacity:.9}.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(280px,1fr));grid-gap:18px;gap:18px}.card{background:var(--surface);border:1px solid var(--border);border-radius:16px;padding:22px;transition:transform .15s,box-shadow .15s}.card:hover{transform:translateY(-3px);box-shadow:0 8px 24px rgba(79,70,229,.15)}.card .icon{font-size:1.8rem}.card h3{margin-top:6px}.card small{color:var(--brand);font-weight:600}.card p{color:var(--muted);margin-top:8px;font-size:.95rem}.lesson h1{font-size:2rem}.lesson h1 small{color:var(--brand);font-size:1rem;font-weight:600}.lesson .intro{color:var(--muted);margin:10px 0 8px;font-size:1.05rem}.lesson section{margin-top:28px}.lesson h2{font-size:1.3rem;margin-bottom:12px;border-left:4px solid var(--brand);padding-left:10px}.table-wrap{overflow-x:auto;background:var(--surface);border:1px solid var(--border);border-radius:12px}table{width:100%;border-collapse:collapse;min-width:480px}td,th{text-align:left;padding:12px 14px;border-bottom:1px solid var(--border);vertical-align:top}th{background:var(--brand-soft);color:var(--brand);font-size:.9rem}tr:last-child td{border-bottom:none}.lesson ul{padding-left:22px}.lesson li{margin-bottom:6px}.footer{text-align:center;color:var(--muted);padding:24px;border-top:1px solid var(--border);font-size:.9rem}@media (max-width:720px){.burger{display:block}.links{display:none;width:100%;flex-direction:column}.links.open{display:flex}}.section-title{font-size:1.5rem;margin:40px 0 6px}.group-title{margin:22px 0 10px;color:var(--brand)}.crumb{margin-bottom:10px;color:var(--brand);font-weight:600}.form-card{background:var(--surface);border:1px solid var(--border);border-radius:14px;padding:16px 18px;margin-bottom:14px}.form-head{display:flex;align-items:center;gap:10px;flex-wrap:wrap;margin-bottom:8px}.form-head .num{background:var(--brand);color:#fff;width:26px;height:26px;border-radius:50%;display:grid;place-items:center;font-size:.85rem;font-weight:700}.bn-tag{color:var(--brand);border-radius:999px;padding:2px 10px;font-size:.85rem;font-weight:600}.bn-tag,.structure{background:var(--brand-soft)}.structure{display:block;color:var(--text);padding:8px 12px;border-radius:8px;font-size:.92rem;overflow-x:auto}.form-card .en{font-size:1.15rem;font-weight:600;margin-top:10px}.form-card .bn-line{color:var(--muted);font-size:1.1rem}.pager{display:flex;justify-content:space-between;gap:12px;margin-top:32px;font-weight:600;color:var(--brand)}.search{width:100%;padding:12px 16px;margin:14px 0 6px;border-radius:12px;border:1px solid var(--border);background:var(--surface);color:var(--text);font-size:1rem}.count{color:var(--muted);font-size:.9rem;margin-bottom:10px}:root{--note-bg:#fff7e0;--note-border:#f0b429;--diff-bg:#eef7ff;--diff-border:#3b9ae1;--rule-bg:#eefaf0;--rule-border:#3fa55b}@media (prefers-color-scheme:dark){:root{--note-bg:#2b2410;--note-border:#b8860b;--diff-bg:#13263a;--diff-border:#3b7fb8;--rule-bg:#142a1a;--rule-border:#2f8048}}.bn{display:block;color:var(--muted);font-weight:500}h1 .bn,h2 .bn,h3 .bn{display:inline;margin-left:8px;font-size:.85em;color:var(--brand)}th .bn{color:inherit;opacity:.85;font-weight:500}.bn-inline{color:var(--brand);font-size:.9em;margin-left:6px}.hero p.bn{color:var(--brand);margin-top:-8px}.card p{display:-webkit-box;-webkit-line-clamp:3;-webkit-box-orient:vertical;overflow:hidden}.sec-intro{color:var(--muted);margin-bottom:10px}.lesson td:first-child{font-weight:600}.box{border-radius:14px;padding:16px 18px;border-left:5px solid var(--border)}.box h2{border-left:none;padding-left:0}.box.note{background:var(--note-bg);border-left-color:var(--note-border)}.box.diff{background:var(--diff-bg);border-left-color:var(--diff-border)}.box.rule{background:var(--rule-bg);border-left-color:var(--rule-border)}.box .table-wrap{background:var(--surface)}