:root{--bg: #f4f5f8;--panel: #ffffff;--panel-2: #f7f8fa;--text: #171a21;--hint: #6b7280;--hint-2: #98a0ad;--border: #e6e8ec;--border-strong: #d7dae0;--accent: #2f6fed;--accent-hover: #2560d6;--accent-tint: #eaf0fe;--accent-text: #ffffff;--success: #17875a;--success-tint: #e5f5ee;--danger: #d1433f;--danger-tint: #fbeae9;--warning: #a8631a;--warning-tint: #fbeee0;--shadow-sm: 0 1px 2px rgba(20, 24, 33, .04);--shadow-card: 0 1px 2px rgba(20, 24, 33, .04), 0 6px 16px -8px rgba(20, 24, 33, .1);--radius-sm: 8px;--radius: 12px;--radius-lg: 16px;--font-ui: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;--font-display: "Inter Tight", var(--font-ui)}@media (prefers-color-scheme: dark){:root{--bg: #0f1115;--panel: #171a21;--panel-2: #1d2029;--text: #edeef1;--hint: #9aa0ac;--hint-2: #6b7280;--border: #2a2e38;--border-strong: #383d49;--accent: #5b8bfa;--accent-hover: #7aa0fb;--accent-tint: rgba(91, 139, 250, .14);--accent-text: #0f1115;--success: #3fbf8f;--success-tint: rgba(63, 191, 143, .14);--danger: #ec6b66;--danger-tint: rgba(236, 107, 102, .14);--warning: #e0a458;--warning-tint: rgba(224, 164, 88, .14);--shadow-sm: 0 1px 2px rgba(0, 0, 0, .3);--shadow-card: 0 1px 2px rgba(0, 0, 0, .3), 0 8px 20px -10px rgba(0, 0, 0, .5)}}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--text);font-family:var(--font-ui);font-size:14px;line-height:1.5;-webkit-font-smoothing:antialiased}h1,h2,h3{font-family:var(--font-display);font-weight:700;letter-spacing:-.01em;margin:0}h1{font-size:1.5rem;margin-bottom:22px}.page-header h1{margin-bottom:4px}h2{font-size:1.15rem}h3{font-family:var(--font-ui);font-size:.78rem;font-weight:600;letter-spacing:.02em;text-transform:uppercase;color:var(--hint);margin:0 0 14px}p{margin:0 0 10px}.muted{color:var(--hint)}.error{color:var(--danger);background:var(--danger-tint);border-radius:var(--radius-sm);padding:8px 12px;font-size:.85rem}.screen-center{min-height:100vh;display:flex;align-items:center;justify-content:center;background:var(--bg)}.login-card{width:340px;display:flex;flex-direction:column;gap:4px;padding:32px}.login-card h1{margin-bottom:2px}.login-card>.muted{margin-bottom:20px}.login-card label{margin-bottom:14px}.login-card .button{margin-top:8px}.layout{display:flex;min-height:100vh}.sidebar{width:232px;flex-shrink:0;background:var(--panel);border-right:1px solid var(--border);display:flex;flex-direction:column;padding:20px 14px;gap:2px}.sidebar-title{font-family:var(--font-display);font-weight:700;font-size:1.02rem;letter-spacing:-.01em;padding:6px 10px 20px}.nav-link{display:block;padding:9px 12px;border-radius:var(--radius-sm);color:var(--text);text-decoration:none;font-size:.88rem;font-weight:500;background:none;border:none;text-align:left;cursor:pointer;transition:background-color .12s ease}.nav-link:hover{background:var(--panel-2)}.nav-link.active{background:var(--accent-tint);color:var(--accent);font-weight:600}.nav-link.logout{margin-top:auto;color:var(--danger)}.nav-link.logout:hover{background:var(--danger-tint)}.content{flex:1;padding:32px 40px 64px;max-width:1180px}.page-header{display:flex;align-items:flex-start;justify-content:space-between;gap:16px;margin-bottom:24px}.page-header .lede{color:var(--hint);font-size:.9rem;margin-top:2px}.card{background:var(--panel);border:1px solid var(--border);border-radius:var(--radius);box-shadow:var(--shadow-card);padding:20px 22px;margin-bottom:20px}.card>*:last-child{margin-bottom:0}.stat-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:16px}.stat{display:flex;flex-direction:column;gap:4px}.stat-label{font-size:.78rem;color:var(--hint)}.stat-value{font-family:var(--font-display);font-size:1.75rem;font-weight:700;letter-spacing:-.01em;font-variant-numeric:tabular-nums}.stat-hint{font-size:.78rem;color:var(--hint-2)}.toolbar{display:flex;flex-wrap:wrap;align-items:flex-end;gap:10px;margin-bottom:20px}.toolbar label{margin-bottom:0}.preset-group{display:flex;flex-wrap:wrap;gap:6px}label{display:flex;flex-direction:column;gap:5px;font-size:.8rem;font-weight:500;color:var(--hint);margin-bottom:14px}input,textarea,select{font:inherit;font-size:.88rem;padding:8px 11px;border-radius:var(--radius-sm);border:1px solid var(--border-strong);background:var(--panel);color:var(--text);transition:border-color .12s ease,box-shadow .12s ease}input:focus,textarea:focus,select:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-tint)}input::placeholder,textarea::placeholder{color:var(--hint-2)}textarea{font-family:var(--font-ui);resize:vertical}.button{display:inline-flex;align-items:center;justify-content:center;gap:6px;background:var(--accent);color:var(--accent-text);border:1px solid transparent;border-radius:var(--radius-sm);padding:8px 16px;font:inherit;font-size:.85rem;font-weight:600;cursor:pointer;transition:background-color .12s ease,border-color .12s ease,transform .05s ease;white-space:nowrap}.button:hover{background:var(--accent-hover)}.button:active{transform:translateY(1px)}.button:disabled{opacity:.5;cursor:default;transform:none}.button:focus-visible{outline:2px solid var(--accent);outline-offset:2px}.button.secondary{background:var(--panel);color:var(--text);border:1px solid var(--border-strong)}.button.secondary:hover{background:var(--panel-2);border-color:var(--hint-2)}.button.danger{background:transparent;color:var(--danger);border:1px solid var(--border-strong)}.button.danger:hover{background:var(--danger-tint);border-color:var(--danger)}.button.small{padding:5px 11px;font-size:.76rem;border-radius:7px}.badge{display:inline-flex;align-items:center;padding:3px 10px;border-radius:999px;background:var(--panel-2);color:var(--hint);font-size:.74rem;font-weight:600;letter-spacing:.01em}.badge-success{background:var(--success-tint);color:var(--success)}.badge-danger{background:var(--danger-tint);color:var(--danger)}.badge-warning{background:var(--warning-tint);color:var(--warning)}.avatar{width:32px;height:32px;border-radius:50%;object-fit:cover;display:block}.avatar-placeholder{display:flex;align-items:center;justify-content:center;background:var(--accent);color:var(--accent-text);font-family:var(--font-display);font-size:.82rem;font-weight:700}.avatar-lg{width:56px;height:56px}.avatar-lg.avatar-placeholder{font-size:1.3rem}table{width:100%;border-collapse:collapse}th,td{text-align:left;padding:11px 12px;border-bottom:1px solid var(--border);font-size:.85rem}th{color:var(--hint);font-weight:600;font-size:.73rem;letter-spacing:.03em;text-transform:uppercase;white-space:nowrap}td:first-child,th:first-child{padding-left:4px}td:last-child,th:last-child{padding-right:4px}tbody tr{transition:background-color .1s ease}tbody tr:hover td{background:var(--panel-2)}tbody tr:last-child td{border-bottom:none}a.row-link{color:inherit;text-decoration:none;display:block}.row{display:flex;gap:10px;align-items:flex-end;flex-wrap:wrap}.row.between{justify-content:space-between;align-items:center}.course-meta{display:flex;align-items:center;gap:12px;margin-bottom:20px}.list{list-style:none;margin:0;padding:0}.list li{padding:9px 0;border-bottom:1px solid var(--border);font-size:.88rem}.list li:last-child{border-bottom:none;padding-bottom:0}.list li:first-child{padding-top:0}.section-gap{margin-top:28px}.chat{display:flex;flex-direction:column;gap:8px;max-height:400px;overflow-y:auto;margin-bottom:14px;padding:4px}.chat-bubble{max-width:70%;padding:9px 13px;border-radius:14px;font-size:.88rem;line-height:1.4}.chat-bubble.in{background:var(--panel-2);border:1px solid var(--border);align-self:flex-start;border-bottom-left-radius:4px}.chat-bubble.out{background:var(--accent);color:var(--accent-text);align-self:flex-end;border-bottom-right-radius:4px}.chat-meta{font-size:.72rem;opacity:.7;margin-top:3px}