:root{--navy:#14306b;--navy2:#1d3f86;--gold:#d6a630;--bg:#f5f6fa;--card:#fff;--ink:#1a2035;
--muted:#5d6680;--line:#e1e5ef;--accent:#2f6fdf;--r:14px}
@media (prefers-color-scheme:dark){:root{--bg:#0f1320;--card:#171d2e;--ink:#e7eaf3;--muted:#9aa3bb;--line:#273049}}
*{box-sizing:border-box}html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.55 system-ui,-apple-system,"Segoe UI",Roboto,
"Noto Sans","Noto Sans Devanagari",sans-serif}
a{color:inherit}
.wrap{max-width:1080px;margin:0 auto;padding:0 16px}
header.top{background:linear-gradient(135deg,var(--navy),var(--navy2));color:#fff}
header.top .wrap{padding-top:22px;padding-bottom:26px}
.crumbs{font-size:14px;opacity:.8;margin-bottom:10px}.crumbs a{text-decoration:none}.crumbs a:hover{text-decoration:underline}
h1{margin:0;font-size:clamp(26px,4.4vw,40px);line-height:1.15;letter-spacing:-.01em}
.sub{margin:8px 0 0;opacity:.85}
.hi{font-weight:600}
.bar{height:4px;background:var(--gold)}
main{padding:28px 0 56px}
h2{font-size:21px;margin:34px 0 4px}h2:first-child{margin-top:0}
.lead{color:var(--muted);margin:0 0 14px;font-size:15px}
.grid{display:grid;gap:14px;grid-template-columns:repeat(auto-fill,minmax(240px,1fr))}
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--r);padding:16px 18px;position:relative}
a.subj{display:block;text-decoration:none;border-top:4px solid var(--a);transition:transform .12s,box-shadow .12s}
a.subj:hover{transform:translateY(-2px);box-shadow:0 8px 24px rgba(20,48,107,.12)}
.subj .code{font:600 12px/1 ui-monospace,monospace;color:var(--a);letter-spacing:.06em}
.subj h3{margin:8px 0 2px;font-size:19px;line-height:1.25}
.subj .meta{color:var(--muted);font-size:14px}
.subj .count{margin-top:12px;font-size:13px;color:var(--muted)}
.qb h3,.sqp h3{margin:0;font-size:17px}
.qb .meta,.sqp .meta{color:var(--muted);font-size:13.5px;margin:2px 0 12px}
.btns{display:flex;gap:8px;flex-wrap:wrap}
.btn{display:inline-flex;align-items:center;gap:6px;padding:8px 13px;border-radius:9px;font-size:14px;font-weight:600;
text-decoration:none;border:1px solid var(--line);background:var(--bg);cursor:pointer;color:var(--ink)}
.btn:hover{border-color:var(--accent)}
.qb .btns{flex-wrap:nowrap}.qb .btn{padding:8px 11px}
.btn.tog{border-color:var(--accent);color:var(--accent);background:transparent}
details[open] .btn.tog{background:var(--accent);color:#fff}
.btn.pri{background:var(--accent);border-color:var(--accent);color:#fff}
.sqps{display:grid;gap:12px}
.sqp{background:var(--card);border:1px solid var(--line);border-radius:var(--r);overflow:hidden}
.sqp .row{display:flex;gap:14px;align-items:center;justify-content:space-between;flex-wrap:wrap;padding:14px 18px}
.sqp .row .meta{margin:2px 0 0}
details summary{list-style:none;cursor:pointer}details summary::-webkit-details-marker{display:none}
details[open] summary .chev{transform:rotate(180deg)}.chev{transition:transform .15s;display:inline-block}
.sol{border-top:1px solid var(--line);padding:16px;background:var(--bg)}
.pages{display:grid;gap:12px;max-width:820px;margin:0 auto}
.pages img{width:100%;height:auto;display:block;background:#fff;border-radius:6px;box-shadow:0 1px 6px rgba(0,0,0,.12)}
.disc{margin-top:8px}
.note{font-size:13.5px;color:var(--muted);background:var(--card);border:1px dashed var(--line);border-radius:10px;padding:10px 14px;margin-top:30px}
footer{color:var(--muted);font-size:13px;padding:0 0 30px}
.setnav{display:flex;gap:6px;flex-wrap:wrap;margin:16px 0 22px}
.setnav a{padding:6px 11px;border-radius:8px;border:1px solid var(--line);background:var(--card);text-decoration:none;font-size:14px}
.setnav a.on{background:var(--accent);color:#fff;border-color:var(--accent)}