:root {
    --primary-color: #2563eb;
    --secondary-color: #3b82f6;
    --success-color: #22c55e;
    --warning-color: #f59e0b;
    --error-color: #ef4444;
    --text-primary: #1e293b;
    --text-secondary: #64748b;
    --bg-light: #f8fafc;
  }
  
  /* Base Styles */
  body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    color: var(--text-primary);
    background-color: var(--bg-light);
    line-height: 1.6;
  }
  
  .container-main {
    max-width: 1280px;
    margin: 2rem auto;
    padding: 0 1rem;
  }
  
  /* Responsive Navigation */
  .navbar-brand {
    font-weight: 600;
    letter-spacing: -0.025em;
  }
  
  .nav-link {
    transition: all 0.2s ease;
    padding: 0.5rem 1rem !important;
    border-radius: 0.375rem;
  }
  
  .nav-link:hover {
    background-color: rgba(255, 255, 255, 0.1);
  }
  
  /* Calculator Form */
  .calculator-card {
    background: white;
    border-radius: 1rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    padding: 2rem;
    margin: 2rem 0;
  }
  
  .input-group-3d {
    position: relative;
  }
  
  .input-group-3d input, 
  .input-group-3d select {
    border: 1px solid #e2e8f0;
    border-radius: 0.5rem;
    padding: 0.875rem 1rem;
    transition: all 0.2s ease;
    width: 100%;
  }
  
  .input-group-3d input:focus,
  .input-group-3d select:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
  }
  
  /* Result Panel */
  .result-card {
    border-left: 4px solid var(--success-color);
    background: white;
    border-radius: 0.75rem;
    padding: 1.5rem;
    margin-top: 2rem;
    animation: slideIn 0.3s ease;
  }
  
  @keyframes slideIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
  }
  
  /* Mobile Optimization */
  @media (max-width: 768px) {
    .calculator-card {
      margin: 1rem -0.5rem;
      border-radius: 0;
    }
    
    .navbar-collapse {
      margin-top: 1rem;
      padding: 1rem;
      background: var(--primary-color);
      border-radius: 0.5rem;
    }
  }
  
  建议配合以下CSS样式（添加到base模板中）：


.input-group-text {
    transition: opacity 0.3s ease;
}
.progress-bar {
    transition: width 0.5s ease, background-color 0.3s ease;
}

/* Cost Breakdown Visual Enhancement */
.cost-breakdown {
    background: #fff;
    border-radius: 1rem;
    box-shadow: 0 2px 12px 0 rgba(37,99,235,0.08);
    padding: 2rem 1.5rem 1.5rem 1.5rem;
    margin-bottom: 2rem;
}
.cost-breakdown .cost-item {
    border: 1.5px solid #e0e7ef;
    box-shadow: 0 1px 4px 0 rgba(37,99,235,0.04);
    transition: box-shadow 0.2s, border-color 0.2s;
    margin-bottom: 0.5rem;
}
.cost-breakdown .cost-item:hover {
    border-color: var(--primary-color);
    box-shadow: 0 4px 16px 0 rgba(37,99,235,0.10);
    background: #f1f5fd;
}
.cost-breakdown .h4.text-primary {
    font-weight: 700;
    letter-spacing: 0.5px;
}
.cost-breakdown .small.text-muted {
    font-size: 0.98rem;
    color: var(--text-secondary);
}
.cost-breakdown .total-cost {
    background: linear-gradient(90deg, #e0e7ef 0%, #f8fafc 100%);
    border-width: 2.5px;
    box-shadow: 0 2px 8px 0 rgba(37,99,235,0.10);
}
.cost-breakdown .total-cost span {
    letter-spacing: 1.5px;
}