:root{--paper:#f2f4f3;--surface:#fff;--surface-2:#e9edec;--ink:#141b1f;--text:#1c2428;--text-dim:#57666b;--line:#d6dedd;--accent:#1c6f68;--accent-strong:#0e4a45;--accent-tint:#e2efec;--danger:#963c3c;--danger-tint:#f6e6e4;--good:#3c7a52;--radius:10px}*{box-sizing:border-box}html,body{margin:0;padding:0}body{background:var(--paper);color:var(--text);font-family:IBM Plex Sans,system-ui,-apple-system,Segoe UI,sans-serif;font-size:15px;line-height:1.5}a{color:var(--accent-strong)}h1,h2,h3{color:var(--ink);margin:0 0 8px}.shell{max-width:1080px;margin:0 auto;padding:28px 24px 80px}.topbar{border-bottom:1px solid var(--line);background:var(--surface);justify-content:space-between;align-items:center;padding:14px 24px;display:flex}.brand{color:var(--ink);letter-spacing:-.01em;font-size:17px;font-weight:700;text-decoration:none}.topbar nav a{color:var(--text-dim);font-weight:500;text-decoration:none}.topbar nav a:hover{color:var(--accent-strong)}.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:18px 20px}.grid{gap:14px;display:grid}.grid.cols-2{grid-template-columns:repeat(2,1fr)}button,.btn{border:1px solid var(--accent);background:var(--accent);color:#fff;cursor:pointer;border-radius:7px;padding:9px 16px;font-family:inherit;font-size:14px;font-weight:600}button.secondary{background:var(--surface);color:var(--accent-strong);border:1px solid var(--line)}button:disabled{opacity:.5;cursor:not-allowed}input,textarea,select{border:1px solid var(--line);background:var(--surface);color:var(--text);border-radius:7px;width:100%;padding:9px 11px;font-family:inherit;font-size:14px}label{color:var(--text-dim);margin-bottom:4px;font-size:12.5px;font-weight:500;display:block}.field{margin-bottom:14px}.error{background:var(--danger-tint);color:var(--danger);border-radius:7px;margin-bottom:14px;padding:9px 12px;font-size:13.5px}.pill{text-transform:uppercase;letter-spacing:.04em;background:var(--accent-tint);color:var(--accent-strong);border-radius:10px;padding:2px 8px;font-size:11px;font-weight:600;display:inline-block}.muted{color:var(--text-dim)}.classroom{grid-template-columns:1.1fr 1fr;gap:16px;height:calc(100vh - 130px);display:grid}.panel{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);flex-direction:column;display:flex;overflow:hidden}.panel-header{border-bottom:1px solid var(--line);text-transform:uppercase;letter-spacing:.06em;color:var(--text-dim);justify-content:space-between;align-items:center;padding:10px 16px;font-size:12px;font-weight:600;display:flex}.panel-tabs{gap:4px;display:flex}.panel-tabs .tab{color:var(--text-dim);text-transform:uppercase;letter-spacing:.06em;cursor:pointer;background:0 0;border:none;border-radius:5px;padding:4px 9px;font-size:12px;font-weight:600}.panel-tabs .tab.active{background:var(--accent-tint);color:var(--accent-strong)}.chat-log{flex-direction:column;flex:1;gap:12px;padding:16px;display:flex;overflow-y:auto}.bubble{white-space:pre-wrap;border-radius:12px;max-width:85%;padding:10px 14px;font-size:14px}.bubble.user{background:var(--accent);color:#fff;border-bottom-right-radius:3px;align-self:flex-end}.bubble.agent{background:var(--surface-2);color:var(--text);border-bottom-left-radius:3px;align-self:flex-start}.bubble.system{color:var(--text-dim);background:0 0;align-self:center;font-size:12.5px;font-style:italic}.chat-input{border-top:1px solid var(--line);gap:8px;padding:12px;display:flex}.chat-input textarea{resize:none;min-height:42px}.whiteboard{flex:1;position:relative;overflow:hidden}.wb-empty{height:100%;color:var(--text-dim);text-align:center;justify-content:center;align-items:center;padding:20px;font-size:13px;display:flex}.strategy-tag{color:var(--text-dim);margin-bottom:4px;font-size:11px}table{border-collapse:collapse;width:100%;font-size:13.5px}th,td{text-align:left;border-bottom:1px solid var(--line);padding:8px 10px}th{color:var(--text-dim);text-transform:uppercase;font-size:12px;font-weight:600}