:root{--bg: #f6f8fb;--card: #ffffff;--text: #1c2733;--muted: #67788c;--primary: #2563eb;--primary-dark: #1d4ed8;--danger: #dc2626;--border: #e3e9f1;--radius: 12px}*{box-sizing:border-box}body{margin:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;background:var(--bg);color:var(--text)}.app-shell{display:flex;min-height:100vh}.sidebar{width:240px;flex-shrink:0;background:#1e293b;color:#e2e8f0;display:flex;flex-direction:column;padding:16px 12px;gap:8px}.sidebar .brand{font-weight:700;font-size:1.25rem;color:#fff;padding:8px 12px 16px;border-bottom:1px solid #334155;margin-bottom:8px}.nav{display:flex;flex-direction:column;gap:4px;flex:1}.nav-item{display:flex;align-items:center;gap:10px;background:transparent;border:none;color:#94a3b8;padding:10px 12px;border-radius:8px;cursor:pointer;font-size:.95rem;text-align:left;width:100%}.nav-item:hover{background:#334155;color:#fff}.nav-item.active{background:var(--primary);color:#fff}.nav-icon{font-size:1.1rem;width:22px;text-align:center}.nav-label{white-space:nowrap}.sidebar .logout{margin-top:auto;align-self:stretch;justify-content:center}.content{flex:1;max-width:960px;width:100%;padding:20px 24px 48px}.topbar{display:flex;align-items:center;gap:16px;padding:14px 0;flex-wrap:wrap}.brand{font-weight:700;font-size:1.15rem;color:var(--primary)}.tabs{display:flex;gap:6px;flex:1;flex-wrap:wrap}.tab{border:none;background:transparent;padding:8px 14px;border-radius:999px;cursor:pointer;color:var(--muted);font-size:.95rem}.tab.active{background:var(--primary);color:#fff}.card{background:var(--card);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:16px}.section-head{display:flex;justify-content:space-between;align-items:center}h2{font-size:1.2rem;margin:12px 0}input,select{padding:9px 12px;border:1px solid var(--border);border-radius:8px;font-size:.95rem;background:#fff;min-width:0}.grid-form{display:grid;grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:12px;align-items:end}.grid-form label{display:flex;flex-direction:column;gap:6px;font-size:.85rem;color:var(--muted)}.grid-form button{grid-column:1 / -1}.row-form{display:flex;gap:8px;flex-wrap:wrap}.row-form input{flex:1}.btn{background:var(--primary);color:#fff;border:none;padding:10px 16px;border-radius:8px;cursor:pointer;font-size:.95rem}.btn:hover{background:var(--primary-dark)}.btn:disabled{opacity:.6;cursor:default}.btn.ghost{background:transparent;color:var(--muted);border:1px solid var(--border)}.btn.danger{background:var(--danger)}.btn.small{padding:6px 10px;font-size:.85rem}.table{width:100%;border-collapse:collapse;background:var(--card);border:1px solid var(--border);border-radius:var(--radius);overflow:hidden}.table th,.table td{text-align:left;padding:12px 14px;border-bottom:1px solid var(--border);font-size:.95rem}.table th{background:#f0f4f9;color:var(--muted);font-weight:600;font-size:.8rem;text-transform:uppercase;letter-spacing:.04em}.table tr:last-child td{border-bottom:none}.badge{background:#fef9c3;border-radius:999px;padding:3px 10px;font-size:.85rem;white-space:nowrap}.list{list-style:none;padding:0;margin:0}.list-item{display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap}.actions{display:flex;gap:8px}.assignment .q{margin:14px 0}.assignment .choices{list-style:none;padding-left:8px;margin:6px 0}.assignment .choices li{padding:3px 0}.assignment .choices li.answer{color:#15803d;font-weight:600}.muted{color:var(--muted)}.small{font-size:.85rem}.error{color:var(--danger);background:#fef2f2;border:1px solid #fecaca;border-radius:8px;padding:10px 12px}.login{min-height:100vh;display:flex;align-items:center;justify-content:center}.login-card{background:var(--card);border:1px solid var(--border);border-radius:16px;padding:40px;text-align:center;max-width:360px;width:100%}.login-card h1{color:var(--primary);margin:0 0 4px}.gsi{display:flex;justify-content:center;margin-top:18px}@media(max-width:768px){.app-shell{flex-direction:column}.sidebar{width:100%;flex-direction:row;flex-wrap:wrap;align-items:center}.sidebar .brand{border-bottom:none;margin:0 8px 0 0}.nav{flex-direction:row;flex-wrap:wrap}.sidebar .logout{margin-top:0;margin-left:auto}.content{padding:16px}.table th:nth-child(2),.table td:nth-child(2){display:none}}