:root{--bg-primary:#0f172a;--bg-secondary:#1e293b;--bg-card:#1e293b;--bg-card-hover:#273549;--border-color:#334155;--text-primary:#f1f5f9;--text-secondary:#94a3b8;--text-muted:#64748b;--accent:#6366f1;--accent-hover:#818cf8;--accent-glow:#6366f126;--success:#22c55e;--success-bg:#22c55e1a;--warning:#f59e0b;--warning-bg:#f59e0b1a;--danger:#ef4444;--danger-bg:#ef44441a;--info:#3b82f6;--info-bg:#3b82f61a;--radius-sm:6px;--radius-md:10px;--radius-lg:16px;--shadow-card:0 1px 3px #0000004d, 0 1px 2px #0003;--shadow-elevated:0 10px 30px #0006;--transition:.2s cubic-bezier(.4, 0, .2, 1)}*{box-sizing:border-box;margin:0;padding:0}body{background:var(--bg-primary);color:var(--text-primary);min-height:100vh;font-family:Inter,-apple-system,BlinkMacSystemFont,sans-serif;line-height:1.5}#app{min-height:100vh;display:flex}.login-page{background:linear-gradient(135deg,#0f172a 0%,#1e1b4b 50%,#0f172a 100%);justify-content:center;align-items:center;width:100%;min-height:100vh;display:flex;position:relative;overflow:hidden}.login-page:before{content:"";background:radial-gradient(circle,#6366f126 0%,#0000 70%);border-radius:50%;width:500px;height:500px;position:absolute;top:-100px;right:-100px}.login-page:after{content:"";background:radial-gradient(circle,#8b5cf61a 0%,#0000 70%);border-radius:50%;width:400px;height:400px;position:absolute;bottom:-80px;left:-80px}.login-card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);width:100%;max-width:420px;box-shadow:var(--shadow-elevated);z-index:1;padding:48px 40px;animation:.5s ease-out fadeInUp;position:relative}@keyframes fadeInUp{0%{opacity:0;transform:translateY(20px)}to{opacity:1;transform:translateY(0)}}.login-card .logo{text-align:center;background:linear-gradient(135deg, var(--accent), #a78bfa);-webkit-text-fill-color:transparent;-webkit-background-clip:text;background-clip:text;margin-bottom:8px;font-size:2rem;font-weight:700}.login-card .subtitle{text-align:center;color:var(--text-secondary);margin-bottom:32px;font-size:.9rem}.form-group{margin-bottom:20px}.form-group label{color:var(--text-secondary);margin-bottom:6px;font-size:.85rem;font-weight:500;display:block}.form-group input{background:var(--bg-primary);border:1px solid var(--border-color);border-radius:var(--radius-md);width:100%;color:var(--text-primary);transition:border-color var(--transition);outline:none;padding:12px 14px;font-family:inherit;font-size:.95rem}.form-group input:focus{border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-glow)}.login-error{color:var(--danger);min-height:22px;margin-bottom:8px;font-size:.85rem}.btn{border-radius:var(--radius-md);cursor:pointer;transition:all var(--transition);border:none;justify-content:center;align-items:center;gap:8px;padding:12px 20px;font-family:inherit;font-size:.95rem;font-weight:500;text-decoration:none;display:inline-flex}.btn-primary{background:var(--accent);color:#fff;width:100%}.btn-primary:hover{background:var(--accent-hover);box-shadow:0 4px 15px var(--accent-glow);transform:translateY(-1px)}.btn-primary:disabled{opacity:.6;cursor:not-allowed;transform:none}.sidebar{background:var(--bg-secondary);border-right:1px solid var(--border-color);z-index:100;width:260px;transition:transform var(--transition);flex-direction:column;display:flex;position:fixed;top:0;bottom:0;left:0}.sidebar-brand{border-bottom:1px solid var(--border-color);align-items:center;gap:12px;padding:24px 20px;display:flex}.sidebar-brand .brand-icon{background:linear-gradient(135deg, var(--accent), #a78bfa);border-radius:var(--radius-md);color:#fff;justify-content:center;align-items:center;width:38px;height:38px;font-size:1.2rem;font-weight:700;display:flex}.sidebar-brand .brand-text{letter-spacing:-.02em;font-size:1.15rem;font-weight:700}.sidebar-brand .brand-sub{color:var(--text-muted);text-transform:uppercase;letter-spacing:.05em;font-size:.72rem}.sidebar-nav{flex-direction:column;flex:1;gap:4px;padding:16px 12px;display:flex}.nav-item{border-radius:var(--radius-md);color:var(--text-secondary);cursor:pointer;transition:all var(--transition);text-align:left;background:0 0;border:none;align-items:center;gap:12px;width:100%;padding:11px 14px;font-family:inherit;font-size:.9rem;font-weight:450;text-decoration:none;display:flex}.nav-item:hover{background:var(--bg-card-hover);color:var(--text-primary)}.nav-item.active{background:var(--accent-glow);color:var(--accent-hover);font-weight:600}.nav-item .nav-icon{text-align:center;width:24px;font-size:1.15rem}.sidebar-footer{border-top:1px solid var(--border-color);padding:16px 14px}.sidebar-footer .user-info{align-items:center;gap:10px;margin-bottom:10px;display:flex}.sidebar-footer .user-avatar{background:linear-gradient(135deg, var(--accent), #a78bfa);border-radius:50%;justify-content:center;align-items:center;width:34px;height:34px;font-size:.85rem;font-weight:600;display:flex}.sidebar-footer .user-name{font-size:.85rem;font-weight:500}.sidebar-footer .user-role{color:var(--text-muted);text-transform:uppercase;letter-spacing:.04em;font-size:.72rem}.btn-logout{border:1px solid var(--border-color);width:100%;color:var(--text-secondary);border-radius:var(--radius-sm);cursor:pointer;transition:all var(--transition);background:0 0;padding:8px;font-family:inherit;font-size:.82rem}.btn-logout:hover{border-color:var(--danger);color:var(--danger);background:var(--danger-bg)}.main-content{flex:1;min-height:100vh;margin-left:260px;padding:28px 32px}.page-header{margin-bottom:28px}.page-header h1{letter-spacing:-.02em;margin-bottom:4px;font-size:1.6rem;font-weight:700}.page-header p{color:var(--text-secondary);font-size:.9rem}.stats-grid{grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:16px;margin-bottom:28px;display:grid}.stat-card{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);transition:all var(--transition);padding:22px}.stat-card:hover{border-color:var(--accent);box-shadow:0 0 0 1px var(--accent-glow);transform:translateY(-2px)}.stat-card .stat-icon{border-radius:var(--radius-md);justify-content:center;align-items:center;width:42px;height:42px;margin-bottom:14px;font-size:1.3rem;display:flex}.stat-card .stat-icon.blue{background:var(--info-bg)}.stat-card .stat-icon.green{background:var(--success-bg)}.stat-card .stat-icon.yellow{background:var(--warning-bg)}.stat-card .stat-icon.red{background:var(--danger-bg)}.stat-card .stat-value{letter-spacing:-.03em;margin-bottom:4px;font-size:2rem;font-weight:700;line-height:1}.stat-card .stat-label{color:var(--text-muted);text-transform:uppercase;letter-spacing:.04em;font-size:.82rem}.table-container{background:var(--bg-card);border:1px solid var(--border-color);border-radius:var(--radius-lg);overflow:hidden}.table-header{border-bottom:1px solid var(--border-color);justify-content:space-between;align-items:center;gap:16px;padding:18px 22px;display:flex}.table-header h2{font-size:1.05rem;font-weight:600}.search-input{background:var(--bg-primary);border:1px solid var(--border-color);border-radius:var(--radius-sm);color:var(--text-primary);width:260px;transition:border-color var(--transition);outline:none;padding:8px 14px;font-family:inherit;font-size:.85rem}.search-input:focus{border-color:var(--accent)}table{border-collapse:collapse;width:100%}thead th{text-align:left;color:var(--text-muted);text-transform:uppercase;letter-spacing:.05em;border-bottom:1px solid var(--border-color);background:#00000026;padding:12px 22px;font-size:.78rem;font-weight:600}tbody tr{border-bottom:1px solid var(--border-color);transition:background var(--transition)}tbody tr:last-child{border-bottom:none}tbody tr:hover{background:var(--bg-card-hover)}tbody td{padding:14px 22px;font-size:.9rem}.user-cell{align-items:center;gap:10px;display:flex}.user-cell .avatar{background:linear-gradient(135deg, var(--accent), #a78bfa);color:#fff;border-radius:50%;flex-shrink:0;justify-content:center;align-items:center;width:32px;height:32px;font-size:.8rem;font-weight:600;display:flex}.user-cell .name{font-weight:500}.user-cell .email{color:var(--text-muted);font-size:.8rem}.badge{border-radius:20px;align-items:center;gap:5px;padding:4px 10px;font-size:.78rem;font-weight:500;display:inline-flex}.badge-admin{color:#c4b5fd;background:#8b5cf626;border:1px solid #8b5cf64d}.badge-teacher{background:var(--info-bg);color:#93c5fd;border:1px solid #3b82f64d}.badge-student{background:var(--success-bg);color:#86efac;border:1px solid #22c55e4d}.role-select{background:var(--bg-primary);border:1px solid var(--border-color);border-radius:var(--radius-sm);color:var(--text-primary);cursor:pointer;transition:border-color var(--transition);outline:none;padding:6px 10px;font-family:inherit;font-size:.82rem}.role-select:focus{border-color:var(--accent)}.role-select:disabled{opacity:.5;cursor:not-allowed}.toast{border-radius:var(--radius-md);z-index:999;box-shadow:var(--shadow-elevated);padding:14px 22px;font-size:.9rem;font-weight:500;animation:.3s ease-out slideInRight;position:fixed;bottom:24px;right:24px}.toast.success{color:#bbf7d0;background:#166534;border:1px solid #22c55e}.toast.error{color:#fecaca;background:#7f1d1d;border:1px solid #ef4444}@keyframes slideInRight{0%{opacity:0;transform:translate(100px)}to{opacity:1;transform:translate(0)}}.loading-spinner{color:var(--text-muted);justify-content:center;align-items:center;gap:10px;padding:60px;display:flex}.loading-spinner:before{content:"";border:2px solid var(--border-color);border-top-color:var(--accent);border-radius:50%;width:20px;height:20px;animation:.8s linear infinite spin}@keyframes spin{to{transform:rotate(360deg)}}.empty-state{text-align:center;color:var(--text-muted);padding:60px 20px}.empty-state .icon{margin-bottom:12px;font-size:3rem}@media (width<=768px){.sidebar{transform:translate(-100%)}.main-content{margin-left:0;padding:20px 16px}.stats-grid{grid-template-columns:1fr 1fr}.table-header{flex-direction:column;align-items:stretch}.search-input{width:100%}}