:root {
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
  
  /* User-Defined Design Palette - Light Theme */
  --bg-primary: #F8F9FA;
  --bg-surface: #FFFFFF;
  --bg-surface-elevated: #FFFFFF;
  --bg-muted: #E9ECEF;
  --bg-subtle: #DEE2E6;
  
  --border-color: #DEE2E6;
  --border-subtle: #E9ECEF;
  --border-active: #5C7CFA;
  
  --text-primary: #212529;
  --text-secondary: #868E96;
  --text-muted: #868E96;
  --text-on-color: #FFFFFF;
  
  --accent-primary: #5C7CFA;
  --accent-primary-hover: #4C6EF5;
  --accent-primary-subtle: #EDF2FF;

  --secondary-main: #4DABF7;
  --secondary-light: #E7F5FF;
  
  --success: #51CF66;
  --success-subtle: rgba(81, 207, 102, 0.15);
  --warning: #FCC419;
  --warning-subtle: rgba(252, 196, 25, 0.15);
  --danger: #FF8787;
  --danger-hover: #fa5252;
  --danger-subtle: rgba(255, 135, 135, 0.15);

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -2px rgba(0, 0, 0, 0.04);
  --shadow-modal: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 10px 10px -5px rgba(0, 0, 0, 0.04);

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --radius-full: 9999px;

  --sidebar-width: 260px;
  --header-height: 64px;
}

[data-theme="dark"] {
  --bg-primary: #121418;
  --bg-surface: #1a1e24;
  --bg-surface-elevated: #242932;
  --bg-muted: #242932;
  --bg-subtle: #2f3642;

  --border-color: #2f3642;
  --border-subtle: #242932;
  --border-active: #5C7CFA;

  --text-primary: #F8F9FA;
  --text-secondary: #adb5bd;
  --text-muted: #868E96;
  --text-on-color: #FFFFFF;

  --accent-primary: #5C7CFA;
  --accent-primary-hover: #748ffc;
  --accent-primary-subtle: rgba(92, 124, 250, 0.18);

  --secondary-main: #4DABF7;
  --secondary-light: rgba(77, 171, 247, 0.18);

  --success: #51CF66;
  --success-subtle: rgba(81, 207, 102, 0.2);
  --warning: #FCC419;
  --warning-subtle: rgba(252, 196, 25, 0.2);
  --danger: #FF8787;
  --danger-hover: #fa5252;
  --danger-subtle: rgba(255, 135, 135, 0.2);

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
  --shadow-modal: 0 20px 25px -5px rgba(0, 0, 0, 0.6);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
}

/* Base Layout */
.app-container {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  width: var(--sidebar-width);
  background-color: var(--bg-surface);
  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 0.2s ease, background-color 0.2s ease;
}

.sidebar-brand {
  height: var(--header-height);
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 12px;
  border-bottom: 1px solid var(--border-color);
}

.brand-icon {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--accent-primary), var(--secondary-main));
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-on-color);
}

.brand-title {
  font-size: 1.05rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--text-primary);
}

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

.nav-link {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 14px;
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.92rem;
  font-weight: 500;
  transition: all 0.15s ease;
}

.nav-link svg {
  width: 20px;
  height: 20px;
  stroke: currentColor;
  stroke-width: 1.8;
  fill: none;
}

.nav-link:hover {
  background-color: var(--bg-muted);
  color: var(--text-primary);
}

.nav-link.active {
  background-color: var(--accent-primary-subtle);
  color: var(--accent-primary);
  font-weight: 600;
}

.sidebar-footer {
  padding: 16px;
  border-top: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.main-wrapper {
  margin-left: var(--sidebar-width);
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.topbar {
  height: var(--header-height);
  background-color: var(--bg-surface);
  border-bottom: 1px solid var(--border-color);
  padding: 0 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  position: sticky;
  top: 0;
  z-index: 30;
}

.topbar-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-primary);
}

.topbar-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.content-area {
  padding: 32px;
  flex: 1;
}

/* UI Elements */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 8px 16px;
  font-size: 0.88rem;
  font-weight: 500;
  border-radius: var(--radius-md);
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.15s ease;
  font-family: inherit;
}

.btn svg {
  width: 16px;
  height: 16px;
  stroke: currentColor;
  stroke-width: 2;
  fill: none;
}

.btn-primary {
  background-color: var(--accent-primary);
  color: var(--text-on-color);
}
.btn-primary:hover {
  background-color: var(--accent-primary-hover);
}

.btn-secondary {
  background-color: var(--bg-muted);
  border-color: var(--border-color);
  color: var(--text-primary);
}
.btn-secondary:hover {
  background-color: var(--bg-subtle);
}

.btn-danger {
  background-color: var(--danger-subtle);
  color: var(--danger);
}
.btn-danger:hover {
  background-color: var(--danger);
  color: var(--text-on-color);
}

.btn-sm {
  padding: 5px 10px;
  font-size: 0.8rem;
}

.btn-icon {
  width: 36px;
  height: 36px;
  padding: 0;
  border-radius: var(--radius-md);
  background-color: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
}
.btn-icon:hover {
  background-color: var(--bg-muted);
  color: var(--text-primary);
}

/* Forms & Inputs */
.form-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 16px;
}

.form-label {
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.form-input {
  padding: 9px 12px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background-color: var(--bg-surface);
  color: var(--text-primary);
  font-size: 0.9rem;
  font-family: inherit;
  outline: none;
  transition: border-color 0.15s ease;
}

.form-input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px var(--accent-primary-subtle);
}

/* Badges */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 8px;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

.badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: currentColor;
}

.badge-dot.pulse {
  animation: pulse-dot 1.8s infinite;
}

@keyframes pulse-dot {
  0% { transform: scale(0.95); opacity: 0.8; }
  50% { transform: scale(1.3); opacity: 1; }
  100% { transform: scale(0.95); opacity: 0.8; }
}

.badge-success { background-color: var(--success-subtle); color: var(--success); }
.badge-warning { background-color: var(--warning-subtle); color: var(--warning); }
.badge-danger { background-color: var(--danger-subtle); color: var(--danger); }
.badge-muted { background-color: var(--bg-muted); color: var(--text-muted); }

/* Table */
.table-container {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

.data-table th {
  background-color: var(--bg-muted);
  padding: 12px 16px;
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border-color);
}

.data-table td {
  padding: 14px 16px;
  font-size: 0.88rem;
  color: var(--text-primary);
  border-bottom: 1px solid var(--border-subtle);
}

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

.data-table tr:hover td {
  background-color: var(--bg-muted);
}

/* Modal Overlay & Dialog */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, 0.45);
  backdrop-filter: blur(4px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  opacity: 0;
  visibility: hidden;
  transition: all 0.2s ease;
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal-box {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  width: 100%;
  max-width: 460px;
  box-shadow: var(--shadow-modal);
  transform: translateY(12px) scale(0.98);
  transition: all 0.2s ease;
  overflow: hidden;
}

.modal-overlay.active .modal-box {
  transform: translateY(0) scale(1);
}

.modal-header {
  padding: 18px 24px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.modal-title {
  font-size: 1.05rem;
  font-weight: 600;
}

.modal-body {
  padding: 20px 24px;
}

.modal-footer {
  padding: 14px 24px;
  border-top: 1px solid var(--border-color);
  background-color: var(--bg-muted);
  display: flex;
  justify-content: flex-end;
  gap: 10px;
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  z-index: 200;
}

.toast {
  padding: 12px 18px;
  border-radius: var(--radius-md);
  background-color: var(--bg-surface);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.88rem;
  font-weight: 500;
  transform: translateY(20px);
  opacity: 0;
  animation: toast-in 0.25s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

@keyframes toast-in {
  to { transform: translateY(0); opacity: 1; }
}

.toast.toast-success { border-left: 4px solid var(--success); }
.toast.toast-error { border-left: 4px solid var(--danger); }
.toast.toast-info { border-left: 4px solid var(--accent-primary); }