:root {
  --primary: #4f46e5;
  --primary-dark: #3730a3;
  --primary-light: #eef2ff;
  --success: #16a34a;
  --warning: #f59e0b;
  --danger: #dc2626;
  --gray-50: #f9fafb;
  --gray-100: #f3f4f6;
  --gray-200: #e5e7eb;
  --gray-300: #d1d5db;
  --gray-400: #9ca3af;
  --gray-500: #6b7280;
  --gray-600: #4b5563;
  --gray-700: #374151;
  --gray-800: #1f2937;
  --gray-900: #111827;
  --sidebar: 260px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: 'Segoe UI', system-ui, sans-serif; background: var(--gray-50); color: var(--gray-800); min-height: 100vh; }

/* ============ LOGIN ============ */
.login-page { display: flex; align-items: center; justify-content: center; min-height: 100vh; background: linear-gradient(135deg, var(--primary) 0%, #7c3aed 100%); padding: 20px; }
.login-card { background: #fff; border-radius: 16px; padding: 40px; width: 100%; max-width: 420px; box-shadow: 0 20px 60px rgba(0,0,0,.2); }
.login-card h1 { font-size: 1.5rem; color: var(--gray-900); margin-bottom: 4px; }
.login-card p { color: var(--gray-500); font-size: .9rem; margin-bottom: 24px; }
.form-group { margin-bottom: 16px; }
.form-group label { display: block; font-size: .85rem; font-weight: 600; color: var(--gray-700); margin-bottom: 4px; }
.form-group input, .form-group select, .form-group textarea { width: 100%; padding: 10px 14px; border: 1.5px solid var(--gray-300); border-radius: 8px; font-size: .9rem; transition: .2s; outline: none; font-family: inherit; }
.form-group input:focus, .form-group select:focus, .form-group textarea:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-light); }
.form-group textarea { min-height: 80px; resize: vertical; }
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 6px; padding: 10px 20px; border-radius: 8px; font-size: .9rem; font-weight: 600; border: none; cursor: pointer; transition: .2s; text-decoration: none; font-family: inherit; }
.btn-primary { background: var(--primary); color: #fff; }
.btn-primary:hover { background: var(--primary-dark); }
.btn-success { background: var(--success); color: #fff; }
.btn-success:hover { background: #15803d; }
.btn-warning { background: var(--warning); color: #fff; }
.btn-warning:hover { background: #d97706; }
.btn-danger { background: var(--danger); color: #fff; }
.btn-danger:hover { background: #b91c1c; }
.btn-outline { background: transparent; border: 1.5px solid var(--gray-300); color: var(--gray-700); }
.btn-outline:hover { background: var(--gray-100); }
.btn-sm { padding: 6px 12px; font-size: .8rem; }
.btn-block { width: 100%; }
.btn:disabled { opacity: .6; cursor: not-allowed; }

/* ============ DASHBOARD LAYOUT ============ */
.app-layout { display: flex; min-height: 100vh; }
.sidebar { width: var(--sidebar); background: var(--gray-900); color: #fff; display: flex; flex-direction: column; position: fixed; top: 0; left: 0; bottom: 0; z-index: 100; transition: transform .3s; }
.sidebar-header { padding: 20px; border-bottom: 1px solid rgba(255,255,255,.1); }
.sidebar-header h2 { font-size: 1.1rem; font-weight: 700; }
.sidebar-header p { font-size: .75rem; color: rgba(255,255,255,.5); margin-top: 2px; }
.sidebar-nav { flex: 1; overflow-y: auto; padding: 12px 0; }
.sidebar-nav a { display: flex; align-items: center; gap: 10px; padding: 10px 20px; color: rgba(255,255,255,.7); text-decoration: none; font-size: .85rem; transition: .2s; border-left: 3px solid transparent; }
.sidebar-nav a:hover, .sidebar-nav a.active { background: rgba(255,255,255,.08); color: #fff; }
.sidebar-nav a.active { border-left-color: var(--primary); }
.sidebar-nav .nav-section { padding: 8px 20px 4px; font-size: .7rem; text-transform: uppercase; letter-spacing: 1px; color: rgba(255,255,255,.35); }
.sidebar-footer { padding: 16px 20px; border-top: 1px solid rgba(255,255,255,.1); }
.sidebar-footer .user-info { font-size: .8rem; }
.sidebar-footer .user-info strong { display: block; color: #fff; }
.sidebar-footer .user-info span { color: rgba(255,255,255,.5); }
.main-content { margin-left: var(--sidebar); flex: 1; min-height: 100vh; }
.top-bar { background: #fff; padding: 12px 24px; border-bottom: 1px solid var(--gray-200); display: flex; align-items: center; justify-content: space-between; position: sticky; top: 0; z-index: 50; }
.top-bar .page-title { font-size: 1.1rem; font-weight: 700; color: var(--gray-900); }
.top-bar .top-actions { display: flex; align-items: center; gap: 12px; }
.menu-toggle { display: none; background: none; border: none; font-size: 1.3rem; cursor: pointer; color: var(--gray-700); }
.content { padding: 24px; }

/* ============ CARDS & STATS ============ */
.stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 16px; margin-bottom: 24px; }
.stat-card { background: #fff; border-radius: 12px; padding: 20px; box-shadow: 0 1px 3px rgba(0,0,0,.08); }
.stat-card .label { font-size: .8rem; color: var(--gray-500); margin-bottom: 4px; }
.stat-card .value { font-size: 1.6rem; font-weight: 700; color: var(--gray-900); }
.stat-card .sub { font-size: .75rem; color: var(--gray-400); margin-top: 2px; }
.card { background: #fff; border-radius: 12px; box-shadow: 0 1px 3px rgba(0,0,0,.08); margin-bottom: 16px; }
.card-header { padding: 16px 20px; border-bottom: 1px solid var(--gray-200); display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 8px; }
.card-header h3 { font-size: .95rem; font-weight: 700; color: var(--gray-800); }
.card-body { padding: 20px; }

/* ============ FILTER BAR ============ */
.filter-bar { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; align-items: center; }
.filter-input { padding: 8px 12px; border: 1.5px solid var(--gray-300); border-radius: 8px; font-size: .85rem; outline: none; min-width: 200px; transition: .2s; font-family: inherit; }
.filter-input:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-light); }
.filter-select { padding: 8px 12px; border: 1.5px solid var(--gray-300); border-radius: 8px; font-size: .85rem; outline: none; background: #fff; cursor: pointer; font-family: inherit; }
.filter-select:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-light); }
.ms-1 { margin-left: 6px; }

/* ============ TABLES ============ */
.table-wrap { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: .85rem; }
thead th { background: var(--gray-50); padding: 10px 14px; text-align: left; font-weight: 600; color: var(--gray-600); border-bottom: 2px solid var(--gray-200); white-space: nowrap; }
tbody td { padding: 10px 14px; border-bottom: 1px solid var(--gray-100); color: var(--gray-700); }
tbody tr:hover { background: var(--gray-50); }
.badge { display: inline-block; padding: 2px 10px; border-radius: 12px; font-size: .75rem; font-weight: 600; }
.badge-success { background: #dcfce7; color: #166534; }
.badge-warning { background: #fef3c7; color: #92400e; }
.badge-danger { background: #fee2e2; color: #991b1b; }
.badge-info { background: #dbeafe; color: #1e40af; }

/* ============ MODAL ============ */
.modal-overlay { display: none; position: fixed; inset: 0; background: rgba(0,0,0,.5); z-index: 200; align-items: center; justify-content: center; padding: 20px; }
.modal-overlay.open { display: flex; }
.modal { background: #fff; border-radius: 16px; max-width: 560px; width: 100%; max-height: 90vh; overflow-y: auto; box-shadow: 0 20px 60px rgba(0,0,0,.2); }
.modal-header { padding: 16px 20px; border-bottom: 1px solid var(--gray-200); display: flex; align-items: center; justify-content: space-between; }
.modal-header h3 { font-size: 1rem; font-weight: 700; }
.modal-close { background: none; border: none; font-size: 1.3rem; cursor: pointer; color: var(--gray-400); padding: 4px; }
.modal-body { padding: 20px; }
.modal-footer { padding: 12px 20px; border-top: 1px solid var(--gray-200); display: flex; gap: 8px; justify-content: flex-end; }

/* ============ SLIDE MODAL ============ */
.slide-modal-overlay { display: none; position: fixed; inset: 0; background: rgba(0,0,0,.5); z-index: 300; align-items: flex-end; justify-content: flex-end; }
.slide-modal-overlay.open { display: flex; }
.slide-modal { background: #fff; width: 520px; max-width: 100vw; height: 100vh; overflow-y: auto; box-shadow: -4px 0 20px rgba(0,0,0,.1); animation: slideInRight .3s ease; }
.slide-modal-header { padding: 16px 20px; border-bottom: 1px solid var(--gray-200); display: flex; align-items: center; justify-content: space-between; position: sticky; top: 0; background: #fff; z-index: 1; }
.slide-modal-header h3 { font-size: 1rem; font-weight: 700; }
.slide-modal-body { padding: 20px; }
@keyframes slideInRight { from { transform: translateX(100%); } to { transform: translateX(0); } }

/* ============ FORM ============ */
.form-row { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; }
.form-actions { display: flex; gap: 8px; justify-content: flex-end; margin-top: 20px; }

/* ============ TOAST ============ */
.toast-container { position: fixed; top: 20px; right: 20px; z-index: 999; display: flex; flex-direction: column; gap: 8px; }
.toast { padding: 12px 20px; border-radius: 8px; color: #fff; font-size: .85rem; font-weight: 500; box-shadow: 0 4px 12px rgba(0,0,0,.15); animation: slideIn .3s ease; min-width: 280px; }
.toast-success { background: var(--success); }
.toast-error { background: var(--danger); }
.toast-warning { background: var(--warning); }
.toast-info { background: var(--primary); }
@keyframes slideIn { from { transform: translateX(100%); opacity: 0; } to { transform: translateX(0); opacity: 1; } }

/* ============ UTILITY ============ */
.text-center { text-align: center; }
.text-right { text-align: right; }
.mt-2 { margin-top: 8px; }
.mt-4 { margin-top: 16px; }
.mb-2 { margin-bottom: 8px; }
.mb-4 { margin-bottom: 16px; }
.flex { display: flex; }
.flex-between { display: flex; justify-content: space-between; align-items: center; }
.gap-2 { gap: 8px; }
.gap-4 { gap: 16px; }
.empty-state { text-align: center; padding: 40px 20px; color: var(--gray-400); }
.empty-state .icon { font-size: 3rem; margin-bottom: 12px; }
.loading { text-align: center; padding: 60px 20px; color: var(--gray-400); font-size: .9rem; }
.menu-toggle { display: none; background: none; border: none; font-size: 1.3rem; cursor: pointer; color: var(--gray-700); padding: 4px 8px; }
.search-bar { padding: 8px 14px; border: 1.5px solid var(--gray-300); border-radius: 8px; font-size: .85rem; outline: none; width: 240px; transition: .2s; }
.search-bar:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-light); }
.loading { text-align: center; padding: 40px; color: var(--gray-400); }

/* ============ TIMETABLE ============ */
.timetable-grid { width: 100%; border-collapse: collapse; }
.timetable-grid th, .timetable-grid td { border: 1px solid var(--gray-200); padding: 8px; text-align: center; vertical-align: middle; font-size: .8rem; }
.timetable-grid th { background: var(--gray-50); font-weight: 600; color: var(--gray-600); }
.tt-cell { cursor: pointer; min-height: 60px; transition: .15s; }
.tt-cell.empty { background: var(--gray-50); color: var(--gray-300); }
.tt-cell.empty:hover { background: var(--primary-light); color: var(--primary); }
.tt-cell.occupied { background: #fff; }
.tt-cell.occupied:hover { background: var(--primary-light); box-shadow: inset 0 0 0 2px var(--primary); }
.tt-subject { font-weight: 600; color: var(--gray-800); }
.tt-teacher { font-size: .75rem; color: var(--gray-500); }
.tt-time { font-size: .7rem; color: var(--gray-400); }
.tt-room { font-size: .7rem; color: var(--gray-500); margin-top: 2px; }
.tt-add { font-size: 1.2rem; }
.gap-1 { gap: 4px; }
.note-item { margin-bottom: 8px; padding: 12px; border: 1px solid var(--border); border-radius: 8px; }
.note-header { display: flex; justify-content: space-between; align-items: start; }
.note-content { margin-top: 6px; color: var(--gray-600); white-space: pre-wrap; }
.note-date { margin-top: 4px; font-size: .75rem; color: var(--gray-400); }

/* ============ RESPONSIVE ============ */
@media (max-width: 768px) {
  .sidebar { transform: translateX(-100%); }
  .sidebar.open { transform: translateX(0); }
  .menu-toggle { display: block; }
  .main-content { margin-left: 0; }
  .form-row { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .search-bar { width: 100%; }
  .card-header { flex-direction: column; align-items: stretch; }
}