:root {
  --primary: #2563eb;
  --dark: #0f172a;
  --light: #f8fafc;
  --danger: #ef4444;
  --success: #10b981;
}

* { margin: 0; padding: 0; box-sizing: border-box; font-family: 'Segoe UI', sans-serif; }

body { background: var(--light); color: #1e293b; }

/* Login */
.login-container {
  display: flex; justify-content: center; align-items: center;
  min-height: 100vh; background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}
.login-box {
  background: white; padding: 40px; border-radius: 10px;
  box-shadow: 0 10px 25px rgba(0,0,0,0.2); width: 90%; max-width: 400px;
}
.login-box h1 { margin-bottom: 30px; text-align: center; color: var(--dark); }
.form-group { margin-bottom: 20px; }
.form-group label { display: block; margin-bottom: 8px; font-weight: 600; }
.form-group input {
  width: 100%; padding: 12px; border: 2px solid #e2e8f0;
  border-radius: 6px; font-size: 16px;
}
.btn {
  width: 100%; padding: 14px; background: var(--primary); color: white;
  border: none; border-radius: 6px; font-size: 16px; font-weight: 600;
  cursor: pointer; transition: 0.3s;
}
.btn:hover { background: #1d4ed8; }
.error-msg {
  background: #fee2e2; color: var(--danger); padding: 12px;
  border-radius: 6px; margin-bottom: 20px; display: none;
}

/* Layout */
.app-container { display: flex; min-height: 100vh; }
.sidebar {
  width: 260px; background: var(--dark); color: white;
  position: fixed; height: 100vh; overflow-y: auto;
}
.sidebar-header { padding: 20px; font-size: 24px; font-weight: bold; border-bottom: 1px solid #1e293b; }
.nav-menu { padding: 20px 0; }
.nav-item {
  padding: 15px 20px; cursor: pointer; transition: 0.3s;
  display: flex; align-items: center; gap: 10px;
}
.nav-item:hover, .nav-item.active { background: #1e293b; }
.nav-item.logout { color: var(--danger); margin-top: auto; }
.main-content {
  flex: 1; margin-left: 260px; padding: 30px;
}
.page-header { margin-bottom: 30px; }
.page-header h1 { font-size: 32px; color: var(--dark); }

/* Cards */
.stats-grid {
  display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 20px; margin-top: 20px;
}
.stat-card {
  background: white; padding: 25px; border-radius: 10px;
  box-shadow: 0 2px 10px rgba(0,0,0,0.05);
}
.stat-card h3 { color: #64748b; font-size: 14px; margin-bottom: 10px; }
.stat-card .value { font-size: 32px; font-weight: bold; color: var(--primary); }

/* Mobile Responsive */
@media (max-width: 768px) {
  .sidebar { width: 100%; height: auto; position: relative; }
  .main-content { margin-left: 0; padding: 15px; }
  .stats-grid { grid-template-columns: 1fr; }
}