:root{--bg:#fafaf9;--fg:#1c1917;--muted:#78716c;--line:#e7e5e4;--accent:#1d4ed8;--ok:#15803d;--bad:#b91c1c;--card:#fff}@media (prefers-color-scheme:dark){:root{--bg:#0c0a09;--fg:#f5f5f4;--muted:#a8a29e;--line:#292524;--accent:#60a5fa;--ok:#4ade80;--bad:#f87171;--card:#1c1917}}*{box-sizing:border-box}body{background:var(--bg);color:var(--fg);margin:0;font:16px/1.5 system-ui,sans-serif}main{max-width:860px;margin:0 auto;padding:16px}nav{border-bottom:1px solid var(--line);flex-wrap:wrap;justify-content:space-between;gap:12px;padding:12px 16px;display:flex}nav a{color:inherit;font-weight:600;text-decoration:none}a{color:var(--accent)}h1{font-size:1.5rem}h2{margin-top:2rem;font-size:1.15rem}.muted{color:var(--muted)}.ok{color:var(--ok)}.bad{color:var(--bad)}.card{background:var(--card);border:1px solid var(--line);border-radius:8px;margin:12px 0;padding:12px 16px}input,textarea,select,button{font:inherit}input[type=text],input[type=email],input[type=password],textarea,select{border:1px solid var(--line);background:var(--card);width:100%;color:var(--fg);border-radius:6px;padding:6px 8px}textarea{min-height:6rem}label{margin:8px 0;display:block}button{border:1px solid var(--accent);background:var(--accent);color:#fff;cursor:pointer;border-radius:6px;padding:6px 14px}button.secondary{color:var(--accent);background:0 0}button.link{color:var(--accent);background:0 0;border:0;padding:0}button:disabled{opacity:.6;cursor:wait}.row{flex-wrap:wrap;align-items:center;gap:8px;display:flex}table{border-collapse:collapse;width:100%}th,td{text-align:left;border-bottom:1px solid var(--line);vertical-align:top;padding:6px 8px}.table-wrap{overflow-x:auto}blockquote{border-left:3px solid var(--line);color:var(--muted);margin:8px 0;padding-left:12px}.lesson-body{white-space:pre-wrap}.chat-msg{margin:6px 0}