/* ==========================================================================
   Design System & Theme Variables
   Inspired by Stripe & Shopify Merchant Dashboards
   ========================================================================== */
:root {
  --primary: #2563EB;
  --primary-hover: #1D4ED8;
  --primary-light: #EFF6FF;
  
  --success: #22C55E;
  --success-light: #F0FDF4;
  --success-border: #BBF7D0;
  
  --warning: #EAB308;
  --warning-light: #FEFCE8;
  --warning-border: #FEF08A;
  
  --danger: #EF4444;
  --danger-light: #FEF2F2;
  --danger-border: #FECACA;

  --bg-page: #F8FAFC;
  --bg-card: #FFFFFF;
  --border-subtle: #E2E8F0;
  
  --text-main: #0F172A;
  --text-muted: #64748B;
  --text-inverse: #FFFFFF;
  
  --shadow-subtle: 0 1px 3px 0 rgba(0, 0, 0, 0.05), 0 1px 2px -1px rgba(0, 0, 0, 0.05);
  --shadow-card: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-hover: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.04);
  
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

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

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

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

/* Sidebar Navigation */
.sidebar {
  width: 260px;
  background-color: var(--bg-card);
  border-right: 1px solid var(--border-subtle);
  display: flex;
  flex-direction: column;
  position: sticky;
  top: 0;
  height: 100vh;
}

.sidebar-brand {
  padding: 24px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.brand-icon {
  background-color: var(--primary);
  color: var(--text-inverse);
  padding: 8px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
}

.brand-text {
  font-size: 1.15rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-main);
}

.sidebar-nav {
  padding: 0 16px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  flex: 1;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: var(--transition);
}

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

.nav-item.active {
  background-color: var(--primary-light);
  color: var(--primary);
  font-weight: 600;
}

.nav-item.disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.sidebar-footer {
  padding: 20px 24px;
  border-top: 1px solid var(--border-subtle);
}

.sync-badge {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 500;
}

.status-indicator {
  width: 8px;
  height: 8px;
  background-color: var(--success);
  border-radius: 50%;
}

/* Main Content Surface */
.main-content {
  flex: 1;
  padding: 32px;
  max-width: 1440px;
  margin: 0 auto;
  overflow-y: auto;
}

.top-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 32px;
}

.header-title h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  color: var(--text-main);
}

.subtitle {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-top: 4px;
}

.btn-primary {
  background-color: var(--primary);
  color: var(--text-inverse);
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-size: 0.9rem;
  font-weight: 600;
  transition: var(--transition);
  display: inline-flex;
  align-items: center;
}

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

/* Metric KPI Cards (6 Grid Layout) */
.kpi-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 20px;
  margin-bottom: 32px;
}

.kpi-card {
  background-color: var(--bg-card);
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
  padding: 20px;
  box-shadow: var(--shadow-subtle);
  transition: var(--transition);
  display: flex;
  flex-direction: column;
}

.kpi-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

.kpi-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 12px;
}

.kpi-title {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.kpi-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
}

.icon-primary { background-color: var(--primary-light); color: var(--primary); }
.icon-success { background-color: var(--success-light); color: var(--success); }
.icon-warning { background-color: var(--warning-light); color: var(--warning); }
.icon-danger  { background-color: var(--danger-light); color: var(--danger); }

.kpi-value {
  font-size: 1.65rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-main);
  margin-bottom: 4px;
}

.kpi-subtext {
  font-size: 0.75rem;
  color: var(--text-muted);
}

.text-warning { color: var(--warning); }
.text-danger { color: var(--danger); }
.text-success { color: var(--success); }

/* Structural Grid & Modular Panels */
.grid-two-column {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-bottom: 32px;
}

.panel {
  background-color: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-subtle);
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
}

.panel-header h3 {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.badge {
  background-color: var(--bg-page);
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid var(--border-subtle);
}

.pill-tag {
  background-color: var(--primary-light);
  color: var(--primary);
  font-size: 0.75rem;
  font-weight: 600;
  padding: 4px 8px;
  border-radius: 999px;
}

/* Alert Items */
.alert-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-height: 280px;
  overflow-y: auto;
}

.alert-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  border: 1px solid transparent;
}

.alert-danger {
  background-color: var(--danger-light);
  border-color: var(--danger-border);
  color: #991B1B;
}

.alert-warning {
  background-color: var(--warning-light);
  border-color: var(--warning-border);
  color: #854D0E;
}

.alert-success {
  background-color: var(--success-light);
  border-color: var(--success-border);
  color: #166534;
}

/* Insights Container */
.insights-container {
  display: flex;
  flex-direction: column;
  gap: 12px;
  max-height: 280px;
  overflow-y: auto;
}

.insight-card {
  padding: 14px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-page);
  border-left: 4px solid var(--primary);
  font-size: 0.875rem;
  color: var(--text-main);
  line-height: 1.4;
}

/* Charts Grid */
.charts-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 32px;
}

.chart-card {
  display: flex;
  flex-direction: column;
}

.chart-wrapper {
  position: relative;
  flex: 1;
  min-height: 240px;
}

/* Top Products Table */
.table-responsive {
  width: 100%;
  overflow-x: auto;
}

.saas-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.875rem;
}

.saas-table th {
  padding: 12px 16px;
  background-color: var(--bg-page);
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  font-size: 0.75rem;
  letter-spacing: 0.05em;
  border-bottom: 1px solid var(--border-subtle);
}

.saas-table td {
  padding: 14px 16px;
  border-bottom: 1px solid var(--border-subtle);
  color: var(--text-main);
}

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

.tag-status {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
}

.tag-healthy { background: var(--success-light); color: var(--success); }
.tag-warning { background: var(--warning-light); color: var(--warning); }
.tag-danger  { background: var(--danger-light); color: var(--danger); }

/* Mobile & Tablet Responsiveness */
@media (max-width: 1100px) {
  .charts-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 900px) {
  .app-layout {
    flex-direction: column;
  }
  
  .sidebar {
    width: 100%;
    height: auto;
    position: relative;
  }

  .sidebar-nav {
    flex-direction: row;
    overflow-x: auto;
    padding-bottom: 12px;
  }

  .grid-two-column {
    grid-template-columns: 1fr;
  }

  .main-content {
    padding: 16px;
  }
}