:root {
  --primary: #4F46E5;
  --primary-light: #818CF8;
  --primary-bg: #EEF2FF;
  --success: #EF4444;
  --success-bg: #FEF2F2;
  --danger: #10B981;
  --danger-bg: #ECFDF5;
  --warning: #F59E0B;
  --warning-bg: #FFFBEB;
  --gray-50: #F9FAFB;
  --gray-100: #F3F4F6;
  --gray-200: #E5E7EB;
  --gray-300: #D1D5DB;
  --gray-400: #9CA3AF;
  --gray-500: #6B7280;
  --gray-600: #4B5563;
  --gray-700: #374151;
  --gray-800: #1F2937;
  --gray-900: #111827;
  --bg: #F5F7FA;
  --card: #FFFFFF;
  --border: #E5E7EB;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.05), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 15px rgba(0,0,0,0.06), 0 4px 6px rgba(0,0,0,0.04);
  --radius: 12px;
  --radius-sm: 8px;
  --transition: all 0.2s ease;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background: var(--bg);
  color: var(--gray-800);
  line-height: 1.6;
  min-height: 100vh;
}

/* Layout */
.app { display: flex; min-height: 100vh; }
.sidebar {
  width: 240px; background: var(--card); border-right: 1px solid var(--border);
  padding: 24px 16px; position: fixed; top: 0; left: 0; height: 100vh;
  overflow-y: auto; z-index: 10;
}
.sidebar-logo { font-size: 18px; font-weight: 700; color: var(--primary); padding: 0 8px 24px; }
.sidebar-logo span { font-size: 12px; color: var(--gray-400); font-weight: 400; display: block; }
.nav-item {
  display: flex; align-items: center; gap: 10px; padding: 10px 12px;
  border-radius: var(--radius-sm); cursor: pointer; transition: var(--transition);
  color: var(--gray-600); font-size: 14px; font-weight: 500; text-decoration: none;
}
.nav-item:hover { background: var(--gray-100); color: var(--gray-800); }
.nav-item.active { background: var(--primary-bg); color: var(--primary); font-weight: 600; }
.nav-item svg { width: 18px; height: 18px; flex-shrink: 0; }
.main { flex: 1; margin-left: 240px; padding: 24px 32px; }
.page { display: none; }
.page.active { display: block; }

/* Header */
.page-header { margin-bottom: 24px; }
.page-title { font-size: 24px; font-weight: 700; color: var(--gray-900); }
.page-subtitle { font-size: 14px; color: var(--gray-500); margin-top: 4px; }

/* Cards */
.card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); box-shadow: var(--shadow); padding: 20px;
  transition: var(--transition);
}
.card:hover { box-shadow: var(--shadow-md); }
.card-title { font-size: 14px; font-weight: 600; color: var(--gray-500); margin-bottom: 12px; text-transform: uppercase; letter-spacing: 0.5px; }

/* Grid */
.grid { display: grid; gap: 16px; }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
@media (max-width: 768px) { .grid-2, .grid-3, .grid-4 { grid-template-columns: 1fr; } }

/* Metric Cards */
.metric { text-align: center; padding: 20px; }
.metric-value { font-size: 32px; font-weight: 700; color: var(--gray-900); }
.metric-label { font-size: 13px; color: var(--gray-500); margin-top: 4px; }
.metric-change { font-size: 12px; margin-top: 4px; font-weight: 500; }
.metric-change.up { color: var(--success); }
.metric-change.down { color: var(--danger); }

/* Signal Banner */
.signal-banner {
  padding: 16px 24px; border-radius: var(--radius); margin-bottom: 24px;
  display: flex; align-items: center; gap: 12px; font-weight: 600; font-size: 16px;
}
.signal-green { background: var(--success-bg); color: #991B1B; border: 1px solid #FECACA; }
.signal-red { background: var(--danger-bg); color: #065F46; border: 1px solid #A7F3D0; }
.signal-yellow { background: var(--warning-bg); color: #92400E; border: 1px solid #FDE68A; }
.signal-icon { font-size: 24px; }

/* Tables */
.table { width: 100%; border-collapse: collapse; font-size: 14px; }
.table th { text-align: left; padding: 10px 12px; color: var(--gray-500); font-weight: 600; font-size: 12px; text-transform: uppercase; border-bottom: 2px solid var(--border); }
.table td { padding: 10px 12px; border-bottom: 1px solid var(--gray-100); }
.table tr:hover td { background: var(--gray-50); }

/* Badges */
.badge {
  display: inline-flex; align-items: center; padding: 2px 8px; border-radius: 99px;
  font-size: 12px; font-weight: 500;
}
.badge-green { background: var(--success-bg); color: #991B1B; }
.badge-red { background: var(--danger-bg); color: #065F46; }
.badge-yellow { background: var(--warning-bg); color: #92400E; }
.badge-blue { background: var(--primary-bg); color: var(--primary); }
.badge-gray { background: var(--gray-100); color: var(--gray-600); }

/* Date Picker */
.date-picker {
  display: flex; align-items: center; gap: 12px; margin-bottom: 24px;
}
.date-picker select {
  padding: 8px 12px; border: 1px solid var(--border); border-radius: var(--radius-sm);
  font-size: 14px; background: var(--card); cursor: pointer; min-width: 200px;
}
.date-picker button {
  padding: 8px 16px; border: 1px solid var(--border); border-radius: var(--radius-sm);
  background: var(--card); cursor: pointer; font-size: 14px;
}
.date-picker button:hover { background: var(--gray-50); }

/* Loading */
.loading { text-align: center; padding: 40px; color: var(--gray-400); }
.loading::after { content: ''; display: inline-block; width: 20px; height: 20px; border: 2px solid var(--gray-300); border-top-color: var(--primary); border-radius: 50%; animation: spin 0.6s linear infinite; margin-left: 8px; vertical-align: middle; }
@keyframes spin { to { transform: rotate(360deg); } }

/* Responsive */
@media (max-width: 768px) {
  .sidebar { display: none; }
  .main { margin-left: 0; padding: 16px; }
}