@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&display=swap');

/* ===== CSS Variables ===== */
:root {
  --bg-primary: #0a0e1a;
  --bg-secondary: #111827;
  --bg-card: #1a1f35;
  --bg-card-hover: #222842;
  --bg-input: #151b2e;
  --border-color: rgba(99, 102, 241, 0.15);
  --border-focus: rgba(99, 102, 241, 0.5);
  --text-primary: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent-primary: #6366f1;
  --accent-secondary: #818cf8;
  --accent-glow: rgba(99, 102, 241, 0.25);
  --gradient-primary: linear-gradient(135deg, #6366f1, #8b5cf6);
  --gradient-card: linear-gradient(135deg, rgba(99,102,241,0.08), rgba(139,92,246,0.04));
  --success: #22c55e;
  --success-bg: rgba(34, 197, 94, 0.1);
  --danger: #ef4444;
  --danger-bg: rgba(239, 68, 68, 0.1);
  --warning: #f59e0b;
  --warning-bg: rgba(245, 158, 11, 0.1);
  --info: #3b82f6;
  --info-bg: rgba(59, 130, 246, 0.1);
  --sidebar-width: 260px;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 8px 40px rgba(0, 0, 0, 0.4);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', -apple-system, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
  line-height: 1.6;
}

.app-layout { display: flex; min-height: 100vh; }

/* ===== Sidebar ===== */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  display: flex; flex-direction: column;
  position: fixed; top: 0; left: 0; bottom: 0;
  z-index: 100; transition: var(--transition);
}

.sidebar-header { padding: 24px 20px; border-bottom: 1px solid var(--border-color); }

.sidebar-logo { display: flex; align-items: center; gap: 12px; text-decoration: none; }

.logo-icon {
  width: 42px; height: 42px;
  background: var(--gradient-primary);
  border-radius: var(--radius);
  display: flex; align-items: center; justify-content: center;
  font-size: 20px;
  box-shadow: 0 4px 15px var(--accent-glow);
}

.logo-text h1 { font-size: 16px; font-weight: 700; color: var(--text-primary); line-height: 1.2; }
.logo-text span { font-size: 11px; color: var(--text-muted); font-weight: 400; }

.sidebar-nav { flex: 1; padding: 16px 12px; display: flex; flex-direction: column; gap: 4px; }

.nav-item {
  display: flex; align-items: center; gap: 12px;
  padding: 12px 16px; border-radius: var(--radius-sm);
  color: var(--text-secondary); text-decoration: none;
  font-size: 14px; font-weight: 500; cursor: pointer;
  transition: var(--transition); border: 1px solid transparent;
  position: relative; overflow: hidden;
}
.nav-item::before {
  content: ''; position: absolute; left: 0; top: 0; bottom: 0;
  width: 3px; background: var(--gradient-primary);
  border-radius: 0 4px 4px 0; opacity: 0; transition: var(--transition);
}
.nav-item:hover { background: rgba(99, 102, 241, 0.08); color: var(--text-primary); }
.nav-item.active { background: rgba(99, 102, 241, 0.12); color: var(--accent-secondary); border-color: var(--border-color); }
.nav-item.active::before { opacity: 1; }

.nav-icon { font-size: 18px; width: 24px; text-align: center; flex-shrink: 0; }

.sidebar-footer { padding: 16px 12px; border-top: 1px solid var(--border-color); }
.sidebar-footer-info { display: flex; align-items: center; gap: 10px; padding: 10px 14px; border-radius: var(--radius-sm); background: var(--gradient-card); }
.footer-avatar { width: 36px; height: 36px; border-radius: 50%; background: var(--gradient-primary); display: flex; align-items: center; justify-content: center; font-size: 14px; font-weight: 600; }
.footer-text p { font-size: 13px; font-weight: 600; }
.footer-text span { font-size: 11px; color: var(--text-muted); }

/* ===== Main Content ===== */
.main-content { flex: 1; margin-left: var(--sidebar-width); padding: 32px; min-height: 100vh; }

/* ===== Page Header ===== */
.page-header { margin-bottom: 32px; }
.page-header h2 {
  font-size: 28px; font-weight: 800;
  background: linear-gradient(135deg, var(--text-primary), var(--accent-secondary));
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text;
  margin-bottom: 6px;
}
.page-header p { color: var(--text-muted); font-size: 14px; }

/* ===== Sections ===== */
.section-page { display: none; animation: fadeSlide 0.4s ease; }
.section-page.active { display: block; }
@keyframes fadeSlide { from { opacity: 0; transform: translateY(12px); } to { opacity: 1; transform: translateY(0); } }

/* ===== Stats Grid ===== */
.stats-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(240px, 1fr)); gap: 20px; margin-bottom: 32px; }

.stat-card {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); padding: 24px;
  position: relative; overflow: hidden; transition: var(--transition);
}
.stat-card::after {
  content: ''; position: absolute; top: 0; left: 0; right: 0;
  height: 3px; background: var(--gradient-primary); opacity: 0; transition: var(--transition);
}
.stat-card:hover { transform: translateY(-3px); border-color: rgba(99, 102, 241, 0.3); box-shadow: 0 8px 30px rgba(99, 102, 241, 0.1); }
.stat-card:hover::after { opacity: 1; }
.stat-card-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 16px; }

.stat-icon { width: 48px; height: 48px; border-radius: var(--radius); display: flex; align-items: center; justify-content: center; font-size: 22px; }
.stat-icon.students { background: var(--info-bg); }
.stat-icon.courses { background: var(--success-bg); }
.stat-icon.records { background: var(--warning-bg); }
.stat-icon.attendance { background: rgba(139, 92, 246, 0.1); }

.stat-value { font-size: 36px; font-weight: 800; line-height: 1; margin-bottom: 4px; }
.stat-label { font-size: 13px; color: var(--text-muted); font-weight: 500; }

/* ===== Content Card ===== */
.content-card { background: var(--bg-card); border: 1px solid var(--border-color); border-radius: var(--radius); overflow: hidden; margin-bottom: 24px; }
.content-card-header { display: flex; align-items: center; justify-content: space-between; padding: 20px 24px; border-bottom: 1px solid var(--border-color); flex-wrap: wrap; gap: 12px; }
.content-card-header h3 { font-size: 16px; font-weight: 700; display: flex; align-items: center; gap: 10px; }
.content-card-header h3 span.icon { font-size: 20px; }
.content-card-body { padding: 24px; }

.header-actions { display: flex; align-items: center; gap: 10px; }

/* ===== Filter Tabs ===== */
.filter-tabs {
  display: flex; background: var(--bg-input); border-radius: var(--radius-sm);
  border: 1px solid var(--border-color); overflow: hidden;
}
.filter-tab {
  padding: 8px 18px; font-family: 'Inter', sans-serif; font-size: 13px; font-weight: 600;
  background: transparent; color: var(--text-muted); border: none; cursor: pointer;
  transition: var(--transition);
}
.filter-tab:hover { color: var(--text-primary); }
.filter-tab.active { background: var(--gradient-primary); color: #fff; }

/* ===== Forms ===== */
.form-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 20px; }
.form-group { display: flex; flex-direction: column; gap: 6px; }
.form-group label { font-size: 13px; font-weight: 600; color: var(--text-secondary); text-transform: uppercase; letter-spacing: 0.5px; }
.form-group input, .form-group select, .form-group textarea {
  background: var(--bg-input); border: 1px solid var(--border-color);
  border-radius: var(--radius-sm); padding: 12px 16px; color: var(--text-primary);
  font-family: 'Inter', sans-serif; font-size: 14px; transition: var(--transition); outline: none;
}
.form-group input:focus, .form-group select:focus, .form-group textarea:focus { border-color: var(--accent-primary); box-shadow: 0 0 0 3px var(--accent-glow); }
.form-group input::placeholder { color: var(--text-muted); }
.form-group select option { background: var(--bg-secondary); color: var(--text-primary); }
.form-actions { display: flex; justify-content: flex-end; gap: 12px; margin-top: 20px; }

/* ===== Buttons ===== */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 12px 24px; border-radius: var(--radius-sm);
  font-family: 'Inter', sans-serif; font-size: 14px; font-weight: 600;
  border: none; cursor: pointer; transition: var(--transition); text-decoration: none;
}
.btn-primary { background: var(--gradient-primary); color: #fff; box-shadow: 0 4px 15px var(--accent-glow); }
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 6px 20px rgba(99, 102, 241, 0.4); }
.btn-secondary { background: rgba(99, 102, 241, 0.1); color: var(--accent-secondary); border: 1px solid var(--border-color); }
.btn-secondary:hover { background: rgba(99, 102, 241, 0.18); }
.btn-danger { background: var(--danger-bg); color: var(--danger); }
.btn-danger:hover { background: rgba(239, 68, 68, 0.2); }
.btn-success { background: var(--success-bg); color: var(--success); }
.btn-success:hover { background: rgba(34, 197, 94, 0.2); }
.btn-warning { background: var(--warning-bg); color: var(--warning); }
.btn-warning:hover { background: rgba(245, 158, 11, 0.2); }
.btn-sm { padding: 8px 14px; font-size: 12px; }
.btn-xs { padding: 6px 10px; font-size: 11px; border-radius: 6px; }

.action-btns { display: flex; gap: 6px; }

/* ===== Tables ===== */
.table-wrapper { overflow-x: auto; }
table { width: 100%; border-collapse: collapse; }
thead th {
  padding: 14px 20px; text-align: left; font-size: 12px; font-weight: 700;
  color: var(--text-muted); text-transform: uppercase; letter-spacing: 0.8px;
  border-bottom: 1px solid var(--border-color); background: rgba(0, 0, 0, 0.15); white-space: nowrap;
}
tbody tr { transition: var(--transition); border-bottom: 1px solid rgba(99, 102, 241, 0.06); }
tbody tr:hover { background: rgba(99, 102, 241, 0.04); }
tbody td { padding: 14px 20px; font-size: 14px; color: var(--text-secondary); white-space: nowrap; }
tbody td:first-child { color: var(--text-primary); font-weight: 500; }

/* ===== Badges ===== */
.badge { display: inline-flex; align-items: center; gap: 5px; padding: 4px 12px; border-radius: 20px; font-size: 12px; font-weight: 600; }
.badge-presente { background: var(--success-bg); color: var(--success); }
.badge-ausente { background: var(--danger-bg); color: var(--danger); }
.badge-ativo { background: var(--success-bg); color: var(--success); }
.badge-inativo { background: var(--danger-bg); color: var(--danger); }

/* ===== Modal ===== */
.modal-overlay {
  position: fixed; inset: 0; background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px); z-index: 1000;
  display: none; align-items: center; justify-content: center;
  animation: fadeIn 0.2s ease;
}
.modal-overlay.show { display: flex; }
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }

.modal {
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius); width: 90%; max-width: 560px;
  box-shadow: var(--shadow-lg);
  animation: modalSlide 0.3s ease;
}
@keyframes modalSlide { from { opacity: 0; transform: translateY(-20px) scale(0.97); } to { opacity: 1; transform: translateY(0) scale(1); } }

.modal-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 20px 24px; border-bottom: 1px solid var(--border-color);
}
.modal-header h3 { font-size: 18px; font-weight: 700; }
.modal-close {
  width: 32px; height: 32px; border-radius: 50%;
  background: rgba(239, 68, 68, 0.1); color: var(--danger);
  border: none; font-size: 20px; cursor: pointer;
  display: flex; align-items: center; justify-content: center;
  transition: var(--transition);
}
.modal-close:hover { background: rgba(239, 68, 68, 0.2); }
.modal-body { padding: 24px; }
.modal-body .form-grid { grid-template-columns: 1fr 1fr; }
.modal-footer { display: flex; justify-content: flex-end; gap: 12px; padding: 16px 24px; border-top: 1px solid var(--border-color); }

/* ===== Toast ===== */
.toast-container { position: fixed; top: 24px; right: 24px; z-index: 9999; display: flex; flex-direction: column; gap: 10px; }
.toast {
  padding: 14px 20px; border-radius: var(--radius-sm); font-size: 14px; font-weight: 500;
  color: #fff; box-shadow: var(--shadow-lg);
  display: flex; align-items: center; gap: 10px;
  animation: toastIn 0.4s ease; min-width: 300px;
}
.toast-success { background: linear-gradient(135deg, #059669, #10b981); }
.toast-error { background: linear-gradient(135deg, #dc2626, #ef4444); }
.toast.removing { animation: toastOut 0.3s ease forwards; }
@keyframes toastIn { from { opacity: 0; transform: translateX(100px); } to { opacity: 1; transform: translateX(0); } }
@keyframes toastOut { from { opacity: 1; transform: translateX(0); } to { opacity: 0; transform: translateX(100px); } }

/* ===== Confirm Dialog ===== */
.confirm-text { font-size: 15px; color: var(--text-secondary); line-height: 1.6; text-align: center; padding: 12px 0; }
.confirm-text strong { color: var(--text-primary); }

/* ===== Empty State ===== */
.empty-state { text-align: center; padding: 48px 24px; color: var(--text-muted); }
.empty-state .icon { font-size: 48px; margin-bottom: 12px; opacity: 0.4; }
.empty-state p { font-size: 15px; }

/* ===== Spinner ===== */
.spinner { display: inline-block; width: 20px; height: 20px; border: 2px solid rgba(255,255,255,0.3); border-top-color: #fff; border-radius: 50%; animation: spin 0.6s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

/* ===== Mobile ===== */
.mobile-menu-btn {
  display: none; position: fixed; top: 16px; left: 16px; z-index: 200;
  background: var(--bg-card); border: 1px solid var(--border-color);
  border-radius: var(--radius-sm); padding: 10px 12px;
  color: var(--text-primary); font-size: 20px; cursor: pointer;
}

@media (max-width: 768px) {
  .mobile-menu-btn { display: block; }
  .sidebar { transform: translateX(-100%); }
  .sidebar.open { transform: translateX(0); }
  .main-content { margin-left: 0; padding: 72px 16px 24px; }
  .stats-grid { grid-template-columns: 1fr 1fr; }
  .form-grid { grid-template-columns: 1fr; }
  .modal-body .form-grid { grid-template-columns: 1fr; }
  .page-header h2 { font-size: 22px; }
  .content-card-header { flex-direction: column; align-items: flex-start; }
}
@media (max-width: 480px) { .stats-grid { grid-template-columns: 1fr; } }

/* ===== Scrollbar ===== */
::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: rgba(99, 102, 241, 0.3); border-radius: 10px; }
::-webkit-scrollbar-thumb:hover { background: rgba(99, 102, 241, 0.5); }