:root{
  --bg:#07131b;--bg2:#0a1b24;--panel:#0d222d;--panel2:#112b37;--text:#f5f8fa;
  --muted:#9fb5c0;--teal:#2ed2bf;--gold:#f2c75c;--purple:#a47cff;--line:rgba(255,255,255,.10);
  --ok:#54db91;--danger:#ff7c89;
}
*{box-sizing:border-box} html{scroll-behavior:smooth}
body{margin:0;font-family:Inter,system-ui,-apple-system,Segoe UI,sans-serif;color:var(--text);
background:
radial-gradient(circle at 15% 0%,rgba(46,210,191,.13),transparent 28%),
radial-gradient(circle at 88% 10%,rgba(164,124,255,.10),transparent 25%),var(--bg);}
a{color:inherit}.topbar{position:sticky;top:0;z-index:30;display:flex;align-items:center;justify-content:space-between;
padding:12px 4vw;background:rgba(5,15,22,.92);backdrop-filter:blur(14px);border-bottom:1px solid var(--line)}
.brand{display:flex;align-items:center;gap:12px;text-decoration:none}.brand-mark{width:42px;height:42px;border-radius:13px;
display:grid;place-items:center;background:linear-gradient(135deg,var(--gold),#8b6c1f);color:#07131b;font-size:25px;font-weight:900}
.brand strong{display:block;letter-spacing:.04em}.brand small{display:block;color:var(--muted);font-size:10px;letter-spacing:.12em;margin-top:3px}
.nav{display:flex;gap:8px;flex-wrap:wrap}.nav a{text-decoration:none;color:var(--muted);padding:9px 13px;border-radius:999px}
.nav a:hover,.nav a.active{background:rgba(46,210,191,.12);color:#fff}
.page{width:min(1220px,92vw);margin:auto}
.hero{display:grid;grid-template-columns:1.35fr .75fr;gap:28px;align-items:center;padding:64px 0 38px}
.eyebrow{display:inline-block;color:var(--teal);font-size:12px;font-weight:900;letter-spacing:.16em}
.hero h1{font-size:clamp(42px,6vw,74px);line-height:.98;margin:12px 0 16px}.hero h1 span{color:var(--gold)}
.hero p{font-size:18px;line-height:1.65;color:var(--muted);max-width:760px}
.hero-panel{padding:26px;border:1px solid var(--line);border-radius:22px;background:linear-gradient(145deg,#12303c,#0b1e27);
box-shadow:0 28px 80px rgba(0,0,0,.25)}.hero-panel h3{margin:0 0 8px;font-size:22px}.hero-panel p{font-size:15px;margin:0}
.stats{display:flex;gap:12px;margin-top:18px;flex-wrap:wrap}.stat{padding:10px 12px;border-radius:12px;background:rgba(255,255,255,.05);border:1px solid var(--line)}
.section{padding:24px 0 58px}.section-head{display:flex;align-items:flex-end;justify-content:space-between;gap:20px;margin-bottom:20px}
.section-head h2{font-size:34px;margin:4px 0}.search{width:min(360px,100%);padding:13px 14px;border-radius:13px;border:1px solid var(--line);background:#0a1c25;color:#fff}
.subject-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}
.subject-card{border:1px solid var(--line);border-radius:20px;background:linear-gradient(145deg,#102733,#0b1b24);padding:22px;display:flex;flex-direction:column;min-height:270px}
.subject-card.featured{grid-column:span 2;background:linear-gradient(145deg,#143b48,#0d2832)}
.subject-top{display:flex;align-items:center;justify-content:space-between;gap:12px}.subject-icon{font-size:34px}.badge{font-size:11px;font-weight:900;color:var(--teal);letter-spacing:.08em}
.subject-card h3{font-size:25px;margin:12px 0 8px}.subject-card p{color:var(--muted);line-height:1.5;margin:0}.topics{display:flex;flex-wrap:wrap;gap:7px;margin:16px 0}
.topics span{font-size:12px;color:#c7d6dd;padding:6px 8px;border-radius:999px;background:rgba(255,255,255,.05);border:1px solid var(--line)}
.card-actions{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-top:auto}.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;text-decoration:none;border:0;border-radius:12px;padding:12px 14px;font-weight:900;cursor:pointer}
.btn.primary{background:var(--teal);color:#05231f}.btn.secondary{background:rgba(164,124,255,.14);color:#e9e0ff;border:1px solid rgba(164,124,255,.34)}
.btn.gold{background:var(--gold);color:#271f07}.btn.ghost{background:transparent;color:#d7e4e9;border:1px solid var(--line)}
.study-shell{display:grid;grid-template-columns:minmax(0,1.2fr) minmax(320px,.8fr);gap:18px;align-items:start;padding:30px 0 70px}
.study-content,.chat-panel,.sidebar-card{border:1px solid var(--line);border-radius:20px;background:#0b1d26}
.study-content{padding:26px}.study-head{display:flex;justify-content:space-between;gap:20px;align-items:flex-start}
.study-head h1{font-size:40px;margin:8px 0}.study-head p{color:var(--muted);line-height:1.6}
.unit-tabs{display:flex;gap:8px;overflow:auto;padding:5px 0 18px}.unit-tabs button{white-space:nowrap;border:1px solid var(--line);background:#102832;color:#d7e3e8;border-radius:999px;padding:9px 12px;cursor:pointer}
.unit-tabs button.active{background:rgba(46,210,191,.16);border-color:rgba(46,210,191,.38);color:#fff}
.lesson-block{border-top:1px solid var(--line);padding-top:20px}.lesson-block h2{font-size:30px;margin:0 0 10px}.lesson-block h3{margin-top:24px}
.lesson-block p,.lesson-block li{color:#c5d4db;line-height:1.7}.example,.exercise,.tip{padding:18px;border-radius:16px;margin:18px 0;border:1px solid var(--line)}
.example{background:#102b35}.exercise{background:#131f2b}.tip{background:rgba(242,199,92,.08);border-color:rgba(242,199,92,.26)}
.exercise details{margin-top:10px}.exercise summary{cursor:pointer;color:var(--teal);font-weight:900}
.study-side{display:grid;gap:16px;position:sticky;top:92px}.sidebar-card{padding:18px}.sidebar-card h3{margin:0 0 8px}.sidebar-card p{color:var(--muted);line-height:1.55}
.room-code{display:flex;align-items:center;gap:10px;margin-top:12px;padding:12px;border-radius:12px;background:#102832}.room-code strong{color:var(--gold);letter-spacing:.1em}
.chat-panel{overflow:hidden;display:flex;flex-direction:column;min-height:560px}.chat-head{padding:16px 18px;display:flex;justify-content:space-between;align-items:center;border-bottom:1px solid var(--line)}
.chat-head small{display:block;color:var(--muted);margin-top:3px}.online-dot{width:10px;height:10px;border-radius:50%;background:var(--ok);box-shadow:0 0 14px var(--ok)}
.chat-rules{padding:10px 14px;background:#102a34;color:#bed1d9;font-size:12px;line-height:1.4}.messages{flex:1;min-height:280px;max-height:420px;overflow:auto;padding:14px}
.msg{padding:10px 12px;border-radius:13px;background:#102832;margin:8px 0}.msg strong{color:var(--teal);font-size:13px}.msg time{color:#78919b;font-size:11px;margin-left:8px}.msg p{margin:5px 0 0;white-space:pre-wrap;word-break:break-word}
.chat-form{border-top:1px solid var(--line);padding:12px;display:grid;gap:8px}.chat-form input{width:100%;padding:11px 12px;border-radius:10px;border:1px solid var(--line);background:#07151c;color:#fff}
.send-row{display:flex;gap:8px}.send-row button{border:0;border-radius:10px;padding:0 16px;background:var(--teal);font-weight:900;color:#05231f}
.enem-grid{display:grid;grid-template-columns:repeat(5,1fr);gap:12px}.enem-card{padding:18px;border-radius:17px;border:1px solid var(--line);background:#0d222d}
.enem-card h3{margin:8px 0}.enem-card p{color:var(--muted);font-size:14px;line-height:1.5}.enem-card a{color:var(--teal);font-weight:900;text-decoration:none}
.notice{padding:16px 18px;border-radius:14px;background:rgba(46,210,191,.08);border:1px solid rgba(46,210,191,.22);color:#cbeae6}
.footer-note{padding:24px 0 50px;color:#78929e;text-align:center;font-size:13px}
@media(max-width:950px){.hero,.study-shell{grid-template-columns:1fr}.study-side{position:static}.subject-grid{grid-template-columns:1fr 1fr}.enem-grid{grid-template-columns:1fr 1fr}.subject-card.featured{grid-column:span 2}}
@media(max-width:650px){.nav{display:none}.hero{padding-top:38px}.hero h1{font-size:46px}.subject-grid,.enem-grid{grid-template-columns:1fr}.subject-card.featured{grid-column:span 1}.section-head{flex-direction:column;align-items:stretch}.card-actions{grid-template-columns:1fr}.study-head{display:block}.study-content{padding:18px}.study-head h1{font-size:32px}.send-row{flex-direction:column}.send-row button{padding:12px}.brand small{display:none}}