:root {
  --bg-primary: #0a0a0b;
  --bg-secondary: #111113;
  --bg-tertiary: #1a1a1d;
  --bg-card: #16161a;
  --bg-hover: #1e1e22;
  --bg-input: #1a1a1d;
  --border-color: #2a2a2e;
  --border-focus: #5b5bd6;
  --text-primary: #ececef;
  --text-secondary: #8b8b8e;
  --text-muted: #5c5c5f;
  --accent: #5b5bd6;
  --accent-hover: #6e6ede;
  --accent-subtle: rgba(91, 91, 214, 0.15);
  --success: #30a46c;
  --warning: #f5a623;
  --danger: #e5484d;
  --danger-hover: #f26367;
  --sidebar-width: 260px;
  --radius: 8px;
  --radius-sm: 6px;
  --transition: 150ms ease;
}

/* 1. Reset & Base */
*, *::before, *::after {
  box-sizing: border-box;
}

body, h1, h2, h3, h4, p, ul, ol {
  margin: 0;
  padding: 0;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover {
  color: var(--accent-hover);
}

/* 16. Scrollbar */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: var(--bg-primary); 
}
::-webkit-scrollbar-thumb {
  background: var(--border-color); 
  border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted); 
}

/* 2. Layout */
.layout {
  display: flex;
  min-height: 100vh;
}

/* Mobile Menu Toggle (CSS Hack) */
.menu-toggle-checkbox {
  display: none;
}
.mobile-header {
  display: none;
}
.sidebar-overlay {
  display: none;
}

/* 3. Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background-color: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  z-index: 40;
  transition: transform var(--transition);
}

.sidebar-header {
  padding: 24px;
  font-size: 1.25rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 12px;
  border-bottom: 1px solid var(--border-color);
}

.sidebar-header .icon {
  color: var(--text-primary);
  font-size: 1.5rem;
}

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

.nav-link {
  display: flex;
  align-items: center;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  font-weight: 500;
  transition: background-color var(--transition), color var(--transition);
}

.nav-link:hover:not(.disabled) {
  background-color: var(--bg-hover);
  color: var(--text-primary);
}

.nav-link.active {
  background-color: var(--accent-subtle);
  color: var(--accent);
}

.nav-link.disabled {
  color: var(--text-muted);
  cursor: not-allowed;
  pointer-events: none;
}

.sidebar-footer {
  padding: 16px;
  border-top: 1px solid var(--border-color);
}

.user-info {
  margin-bottom: 12px;
  display: flex;
  flex-direction: column;
}

.user-info .username {
  font-weight: 600;
  font-size: 0.9rem;
}

.user-info a {
  font-size: 0.8rem;
  color: var(--text-secondary);
}
.user-info a:hover {
  color: var(--text-primary);
}

/* 4. Main Content */
.main-wrapper {
  flex: 1;
  margin-left: var(--sidebar-width);
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.main-content {
  padding: 32px;
  max-width: 1200px;
  width: 100%;
  margin: 0 auto;
}

/* 5. Typography */
h1 { font-size: 2rem; font-weight: 700; margin-bottom: 1rem; }
h2 { font-size: 1.5rem; font-weight: 600; margin-bottom: 0.75rem; }
h3 { font-size: 1.25rem; font-weight: 600; margin-bottom: 0.5rem; }
p { margin-bottom: 1rem; color: var(--text-secondary); }
small { font-size: 0.875rem; }

.text-muted { color: var(--text-muted); }
.text-secondary { color: var(--text-secondary); }
.text-center { text-align: center; }

/* 6. Cards & Stats Grid */
.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 24px;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

/* 7. Stat Cards */
.stat-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  align-items: center;
  gap: 16px;
}

.stat-icon {
  font-size: 2rem;
  background-color: var(--bg-tertiary);
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius);
}

.stat-info {
  display: flex;
  flex-direction: column;
}

.stat-label {
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

/* 8. Forms */
.form-group {
  margin-bottom: 16px;
  display: flex;
  flex-direction: column;
}

.form-label {
  margin-bottom: 6px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.form-input {
  background-color: var(--bg-input);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  transition: border-color var(--transition), box-shadow var(--transition);
  width: 100%;
}

.form-input:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 2px var(--accent-subtle);
}

.form-error {
  color: var(--danger);
  font-size: 0.8rem;
  margin-top: 4px;
}

/* 9. Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  font-weight: 500;
  font-size: 0.95rem;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all var(--transition);
  text-decoration: none;
}
.btn:disabled, .btn[disabled] {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-primary {
  background-color: var(--accent);
  color: #fff;
}
.btn-primary:hover:not(:disabled) {
  background-color: var(--accent-hover);
}

.btn-danger {
  background-color: var(--danger);
  color: #fff;
}
.btn-danger:hover:not(:disabled) {
  background-color: var(--danger-hover);
}

.btn-ghost {
  background-color: transparent;
  color: var(--text-secondary);
  border-color: var(--border-color);
}
.btn-ghost:hover:not(:disabled) {
  background-color: var(--bg-hover);
  color: var(--text-primary);
}

.btn-sm {
  padding: 6px 12px;
  font-size: 0.85rem;
}
.w-full {
  width: 100%;
}

/* 10. Messages/Alerts */
.messages {
  margin-bottom: 24px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.alert {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  border: 1px solid var(--border-color);
  background-color: var(--bg-card);
}

.alert-success {
  background-color: rgba(48, 164, 108, 0.1);
  border-color: rgba(48, 164, 108, 0.2);
  color: var(--success);
}

.alert-error, .alert-danger {
  background-color: rgba(229, 72, 77, 0.1);
  border-color: rgba(229, 72, 77, 0.2);
  color: var(--danger);
}

.alert-info {
  background-color: rgba(91, 91, 214, 0.1);
  border-color: rgba(91, 91, 214, 0.2);
  color: var(--accent);
}

/* 11. Tables */
.table-responsive {
  width: 100%;
  overflow-x: auto;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  background: var(--bg-card);
}

table {
  width: 100%;
  border-collapse: collapse;
}

th, td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
  font-size: 0.95rem;
}

th {
  background-color: var(--bg-tertiary);
  color: var(--text-secondary);
  font-weight: 500;
}

tr:last-child td {
  border-bottom: none;
}

tr:hover td {
  background-color: var(--bg-hover);
}

/* 12. Badges */
.badge {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 500;
  background: var(--bg-tertiary);
  border: 1px solid var(--border-color);
}

.badge-success { background: rgba(48, 164, 108, 0.1); color: var(--success); border-color: rgba(48, 164, 108, 0.2); }
.badge-warning { background: rgba(245, 166, 35, 0.1); color: var(--warning); border-color: rgba(245, 166, 35, 0.2); }
.badge-danger { background: rgba(229, 72, 77, 0.1); color: var(--danger); border-color: rgba(229, 72, 77, 0.2); }

/* 13. Empty States */
.empty-state {
  text-align: center;
  padding: 48px 24px;
  background: var(--bg-card);
  border: 1px dashed var(--border-color);
  border-radius: var(--radius);
}
.empty-state .icon {
  font-size: 3rem;
  margin-bottom: 16px;
  opacity: 0.5;
}

/* 14. Utilities */
.flex { display: flex; }
.gap-1 { gap: 4px; }
.gap-2 { gap: 8px; }
.gap-3 { gap: 12px; }
.gap-4 { gap: 16px; }
.mt-sm { margin-top: 12px; }
.mt-md { margin-top: 24px; }
.mt-lg { margin-top: 32px; }
.mb-sm { margin-bottom: 12px; }
.mb-md { margin-bottom: 24px; }
.mb-lg { margin-bottom: 32px; }

/* 15. Responsive */
@media (max-width: 1024px) {
  :root {
    --sidebar-width: 220px;
  }
}

@media (max-width: 768px) {
  .mobile-header {
    display: flex;
    align-items: center;
    padding: 16px;
    background-color: var(--bg-secondary);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 30;
  }
  
  .menu-toggle-label {
    font-size: 1.5rem;
    cursor: pointer;
    margin-right: 16px;
    color: var(--text-primary);
  }
  
  .mobile-logo {
    font-size: 1.25rem;
    font-weight: 600;
  }
  
  .sidebar {
    transform: translateX(-100%);
  }
  
  .main-wrapper {
    margin-left: 0;
  }
  
  /* The hack */
  .menu-toggle-checkbox:checked ~ .layout .sidebar {
    transform: translateX(0);
  }
  
  .menu-toggle-checkbox:checked ~ .layout .sidebar-overlay {
    display: block;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.5);
    z-index: 35;
    backdrop-filter: blur(2px);
  }
}

@media (max-width: 480px) {
  .main-content {
    padding: 16px;
  }
  .stats-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 320px) {
  body {
    overflow-x: hidden;
  }
  .main-content {
    padding: 12px;
  }
}