:root {
  /* Colors */
  --primary: #4F46E5;
  --primary-hover: #4338CA;
  --secondary: #10B981;
  --secondary-hover: #059669;
  --danger: #EF4444;
  --danger-hover: #DC2626;
  --warning: #F59E0B;
  --background: #F3F4F6;
  --surface: #FFFFFF;
  --text-main: #111827;
  --text-muted: #6B7280;
  --border: #E5E7EB;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  
  /* Layout & Spacing */
  --sidebar-width: 260px;
  --header-height: 70px;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  
  /* Effects */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: var(--font-sans);
  background-color: var(--background);
  color: var(--text-main);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  display: flex;
  height: 100vh;
  overflow: hidden;
}

/* Utilities */
.hidden { display: none !important; }
.text-danger { color: var(--danger); }
.text-warning { color: var(--warning); }
.text-success { color: var(--secondary); }
.font-bold { font-weight: 600; }
.flex { display: flex; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: 0.5rem; }
.gap-4 { gap: 1rem; }
.cursor-pointer { cursor: pointer; }

/* Buttons & Inputs */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  border: none;
  font-size: 0.875rem;
}

.btn-primary { background-color: var(--primary); color: white; }
.btn-primary:hover { background-color: var(--primary-hover); }

.btn-secondary { background-color: var(--surface); color: var(--text-main); border: 1px solid var(--border); }
.btn-secondary:hover { background-color: var(--background); }

.btn-danger { background-color: var(--danger); color: white; }
.btn-danger:hover { background-color: var(--danger-hover); }

.btn-sm { padding: 0.25rem 0.5rem; font-size: 0.75rem; }

.input-group { margin-bottom: 1rem; }
.input-label { display: block; font-size: 0.875rem; font-weight: 500; margin-bottom: 0.5rem; color: var(--text-main); }
.input-field {
  width: 100%;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  transition: var(--transition);
  font-family: var(--font-sans);
}
.input-field:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1); }
select.input-field { appearance: none; background-color: white; }

/* Layout: Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background-color: var(--surface);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  z-index: 10;
}

.brand {
  height: var(--header-height);
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  border-bottom: 1px solid var(--border);
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--primary);
  gap: 0.75rem;
}
.brand i { font-size: 1.5rem; }

.nav-menu {
  flex: 1;
  padding: 1.5rem 1rem;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  color: var(--text-muted);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
  cursor: pointer;
}

.nav-item:hover {
  background-color: var(--background);
  color: var(--text-main);
}

.nav-item.active {
  background-color: rgba(79, 70, 229, 0.1);
  color: var(--primary);
}

.nav-item i { font-size: 1.25rem; width: 24px; text-align: center; }

/* Layout: Main Content */
.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.header {
  height: var(--header-height);
  background-color: var(--surface);
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2rem;
  box-shadow: var(--shadow-sm);
  z-index: 5;
}

.header-title { font-size: 1.25rem; font-weight: 600; }

.content-area {
  flex: 1;
  padding: 2rem;
  overflow-y: auto;
}

/* Views Container */
.view-section {
  display: none;
  animation: fadeIn 0.3s ease-out forwards;
}
.view-section.active { display: block; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Dashboard Cards */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.stat-card {
  background-color: var(--surface);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
  gap: 1rem;
  border: 1px solid var(--border);
  transition: var(--transition);
}
.stat-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); }

.stat-header { display: flex; align-items: center; justify-content: space-between; color: var(--text-muted); font-size: 0.875rem; font-weight: 500; }
.stat-icon { width: 40px; height: 40px; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-size: 1.25rem; }
.stat-icon.primary { background-color: rgba(79, 70, 229, 0.1); color: var(--primary); }
.stat-icon.success { background-color: rgba(16, 185, 129, 0.1); color: var(--secondary); }
.stat-icon.warning { background-color: rgba(245, 158, 11, 0.1); color: var(--warning); }
.stat-icon.danger { background-color: rgba(239, 68, 68, 0.1); color: var(--danger); }

.stat-value { font-size: 2rem; font-weight: 700; color: var(--text-main); }

/* Data Tables */
.card {
  background-color: var(--surface);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border);
  overflow: hidden;
  margin-bottom: 2rem;
}


.card-header {
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.card-title { font-weight: 600; font-size: 1.125rem; }

.table-container { overflow-x: auto; }
.data-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}
.data-table th, .data-table td {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
}
.data-table th {
  background-color: #F9FAFB;
  font-weight: 500;
  color: var(--text-muted);
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.data-table tr:hover { background-color: #F9FAFB; }
.data-table tr:last-child td { border-bottom: none; }

.badge {
  display: inline-flex;
  align-items: center;
  padding: 0.125rem 0.5rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 500;
}
.badge-success { background-color: rgba(16, 185, 129, 0.1); color: var(--secondary); }
.badge-danger { background-color: rgba(239, 68, 68, 0.1); color: var(--danger); }
.badge-primary { background-color: rgba(79, 70, 229, 0.1); color: var(--primary); }

.empty-state {
  padding: 3rem;
  text-align: center;
  color: var(--text-muted);
}
.empty-state i { font-size: 3rem; margin-bottom: 1rem; opacity: 0.5; }

/* Modals */
.modal-overlay {
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background-color: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 50;
  backdrop-filter: blur(2px);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}
.modal-overlay.show { opacity: 1; pointer-events: auto; }

.modal {
  background-color: var(--surface);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 500px;
  box-shadow: var(--shadow-lg);
  transform: scale(0.95);
  transition: transform 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
  display: flex;
  flex-direction: column;
  max-height: 90vh;
}
.modal-overlay.show .modal { transform: scale(1); }

.modal-header {
  padding: 1.5rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.modal-title { font-weight: 600; font-size: 1.25rem; }
.modal-close {
  background: none; border: none; font-size: 1.5rem; color: var(--text-muted);
  cursor: pointer; transition: var(--transition);
}
.modal-close:hover { color: var(--text-main); }

.modal-body {
  padding: 1.5rem;
  overflow-y: auto;
}

.modal-footer {
  padding: 1.5rem;
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: flex-end;
  gap: 1rem;
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  z-index: 100;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.toast {
  background-color: var(--surface);
  border-left: 4px solid var(--primary);
  box-shadow: var(--shadow-lg);
  padding: 1rem 1.5rem;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  gap: 1rem;
  animation: slideInRight 0.3s cubic-bezier(0.0, 0.0, 0.2, 1);
}
.toast-success { border-left-color: var(--secondary); }
.toast-success i { color: var(--secondary); }
.toast-error { border-left-color: var(--danger); }
.toast-error i { color: var(--danger); }
.toast-body { font-size: 0.875rem; font-weight: 500; }

@keyframes slideInRight {
  from { transform: translateX(100%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}
@keyframes fadeOut {
  from { opacity: 1; }
  to { opacity: 0; }
}

/* --- Mobile Responsiveness --- */
@media (max-width: 768px) {
  /* Turn container into a vertical stack with nav at the bottom */
  #appContainer {
    flex-direction: column-reverse !important;
  }

  /* Bottom Tab Navigation */
  .sidebar {
    width: 100%;
    height: 60px;
    border-right: none;
    border-top: 1px solid var(--border);
    flex-direction: row;
    z-index: 20;
  }
  .brand { display: none; }
  .nav-menu {
    padding: 0;
    flex-direction: row;
    justify-content: space-around;
    align-items: center;
    width: 100%;
    overflow: visible;
  }
  .nav-item {
    flex-direction: column;
    padding: 0.5rem 0;
    gap: 0.25rem;
    font-size: 0.7rem;
    border-radius: 0;
    flex: 1;
    justify-content: center;
    align-items: center;
  }
  .nav-item.active {
    background-color: transparent;
    color: var(--primary);
    border-top: 2px solid var(--primary);
  }

  /* Header & Content Area */
  .header {
    padding: 0 1rem;
    height: 60px;
  }
  .header-actions .gap-4 { gap: 0.5rem; }
  .header-actions .gap-2 { gap: 0.25rem; }
  
  .content-area {
    padding: 1rem;
    padding-bottom: 2rem; /* Extra space at the bottom */
  }

  /* Hide the clock on very narrow screens */
  #currentTime { display: none; }
  
  /* Cards & Tables */
  .stats-grid { grid-template-columns: 1fr; gap: 1rem; }
  .card-header {
    flex-direction: column;
    align-items: stretch;
    gap: 1rem;
  }
  .card-header button { width: 100%; justify-content: center; }
  .card-header .flex { flex-direction: column; width: 100%; }
  
  /* Modal optimization */
  .modal {
    margin: 1rem;
    width: calc(100% - 2rem);
    max-height: calc(100vh - 2rem);
  }
  
  /* Login Screen */
  #authContainer .card {
    padding: 1.5rem;
    margin: 1rem;
    border: none;
    box-shadow: none;
    background-color: transparent;
  }
}