/* roulang page: index */
/* ----- CSS 变量 & 设计系统 ----- */
    :root {
      --primary: #0B1E3C;
      --primary-deep: #0F2743;
      --accent-cyan: #00C2D1;
      --accent-cyan-hover: #00A8B5;
      --accent-amber: #F59E0B;
      --bg-page: #F7F9FC;
      --bg-card: #FFFFFF;
      --bg-light-gray: #F1F5F9;
      --border-light: #E2E8F0;
      --text-primary: #0B1E3C;
      --text-body: #334155;
      --text-muted: #64748B;
      --text-on-dark: #E2E8F0;
      --success: #10B981;
      --warning: #F59E0B;
      --error: #EF4444;
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
      --font-mono: "Inter", "SF Mono", "Menlo", monospace;
      --shadow-sm: 0 2px 12px rgba(11,30,60,0.06);
      --shadow-md: 0 8px 24px rgba(11,30,60,0.12);
      --radius-lg: 12px;
      --radius-md: 8px;
      --radius-full: 40px;
      --transition: 0.25s ease;
      --container-max: 1200px;
    }
    
    /* ----- 全局重置 & 基础样式 ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    html {
      scroll-behavior: smooth;
      scroll-padding-top: 80px;
    }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg-page);
      color: var(--text-body);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }
    button, input, textarea {
      font-family: inherit;
      font-size: inherit;
    }
    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }
    @media (max-width: 768px) {
      .container {
        padding: 0 20px;
      }
    }
    
    /* ----- 排版工具 ----- */
    h1, h2, h3 {
      color: var(--text-primary);
      font-weight: 600;
    }
    h1 {
      font-size: 36px;
      line-height: 1.2;
    }
    h2 {
      font-size: 28px;
      line-height: 1.3;
      margin-bottom: 16px;
    }
    h3 {
      font-size: 20px;
      line-height: 1.4;
    }
    @media (max-width: 768px) {
      h1 { font-size: 28px; }
      h2 { font-size: 22px; }
      h3 { font-size: 18px; }
    }
    .text-muted { color: var(--text-muted); }
    .text-accent { color: var(--accent-cyan); }
    
    /* ----- 导航 (sticky 白底平台) ----- */
    #header {
      position: sticky;
      top: 0;
      z-index: 100;
      background: rgba(255,255,255,0.95);
      backdrop-filter: blur(8px);
      height: 72px;
      display: flex;
      align-items: center;
      border-bottom: 1px solid transparent;
      transition: box-shadow var(--transition), border-color var(--transition);
    }
    #header.scrolled {
      box-shadow: var(--shadow-sm);
      border-bottom: 1px solid var(--border-light);
    }
    .header-inner {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      display: flex;
      align-items: baseline;
      gap: 8px;
      font-weight: 700;
      font-size: 22px;
      color: var(--primary);
    }
    .logo .domain {
      font-size: 12px;
      color: var(--text-muted);
      font-weight: 400;
      margin-left: 4px;
    }
    .nav-links {
      display: flex;
      gap: 28px;
      align-items: center;
      font-weight: 500;
      color: var(--text-body);
    }
    .nav-links a {
      position: relative;
      padding: 8px 0;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-cyan);
      transition: width var(--transition);
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }
    /* 移动端底部导航 */
    .mobile-bottom-nav {
      display: none;
      position: fixed;
      bottom: 0;
      left: 0;
      right: 0;
      background: rgba(11,30,60,0.9);
      backdrop-filter: blur(10px);
      border-radius: 40px 40px 0 0;
      padding: 12px 24px;
      justify-content: space-around;
      z-index: 110;
      box-shadow: 0 -4px 12px rgba(0,0,0,0.2);
    }
    .mobile-bottom-nav a {
      color: var(--text-on-dark);
      display: flex;
      flex-direction: column;
      align-items: center;
      font-size: 12px;
      gap: 4px;
      opacity: 0.8;
    }
    .mobile-bottom-nav a i {
      font-size: 18px;
    }
    .mobile-bottom-nav a.active {
      color: var(--accent-cyan);
      opacity: 1;
    }
    @media (max-width: 768px) {
      #header { height: 56px; }
      .desktop-nav { display: none; }
      .mobile-bottom-nav { display: flex; }
      .logo { font-size: 20px; }
    }
    
    /* ----- 区块间距 ----- */
    section {
      padding: 80px 0;
    }
    @media (max-width: 768px) {
      section { padding: 60px 0; }
    }
    
    /* ----- 按钮系统 ----- */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 14px 32px;
      border-radius: var(--radius-md);
      font-weight: 600;
      transition: all var(--transition);
      cursor: pointer;
      border: none;
      background: transparent;
      line-height: 1.2;
    }
    .btn-primary {
      background: var(--accent-cyan);
      color: white;
    }
    .btn-primary:hover {
      background: var(--accent-cyan-hover);
      transform: translateY(-2px);
      box-shadow: var(--shadow-md);
    }
    .btn-outline {
      background: white;
      border: 1px solid var(--primary);
      color: var(--primary);
    }
    .btn-outline:hover {
      background: #E8EDF5;
    }
    .btn-link {
      color: var(--accent-cyan);
      padding: 0;
      background: none;
    }
    .btn-link:hover {
      text-decoration: underline;
    }
    
    /* ----- 卡片基础 ----- */
    .card {
      background: var(--bg-card);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-lg);
      padding: 32px;
      box-shadow: var(--shadow-sm);
      transition: box-shadow var(--transition), transform var(--transition);
    }
    .card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-4px);
    }
    
    /* ----- Hero 区域 ----- */
    #hero {
      background: linear-gradient(135deg, #F7F9FC 0%, #E8EDF5 100%);
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      position: relative;
      padding: 100px 0 80px;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }
    .hero-metrics {
      display: flex;
      flex-wrap: wrap;
      gap: 20px;
      margin: 32px 0 24px;
    }
    .metric-card {
      background: white;
      border-radius: var(--radius-md);
      padding: 16px 20px;
      box-shadow: var(--shadow-sm);
      border-top: 3px solid var(--accent-cyan);
      min-width: 120px;
      flex: 1;
    }
    .metric-number {
      font-family: var(--font-mono);
      font-size: 32px;
      font-weight: 700;
      color: var(--primary);
    }
    .metric-label {
      font-size: 13px;
      color: var(--text-muted);
      margin-top: 6px;
    }
    .hero-image img {
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-md);
    }
    @media (max-width: 1024px) {
      .hero-grid {
        grid-template-columns: 1fr;
        gap: 32px;
      }
      .hero-metrics {
        justify-content: center;
      }
    }
    
    /* 服务矩阵 1+2 不对称 */
    .services-grid {
      display: grid;
      grid-template-columns: 1.4fr 1fr;
      gap: 24px;
      margin-top: 32px;
    }
    .service-card-large {
      border-left: 4px solid var(--accent-cyan);
    }
    .service-card-small-group {
      display: flex;
      flex-direction: column;
      gap: 24px;
    }
    .tech-tag {
      display: inline-block;
      background: #F1F5F9;
      color: var(--text-body);
      font-size: 12px;
      padding: 4px 12px;
      border-radius: 20px;
      margin-top: 12px;
      font-weight: 500;
    }
    @media (max-width: 768px) {
      .services-grid {
        grid-template-columns: 1fr;
      }
    }
    
    /* 对比表格 */
    .comparison-table {
      width: 100%;
      border-collapse: collapse;
      margin: 24px 0;
      background: white;
      border-radius: var(--radius-lg);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
    }
    .comparison-table th {
      background: #F1F5F9;
      padding: 16px;
      text-align: left;
      font-weight: 600;
    }
    .comparison-table td {
      padding: 16px;
      border-bottom: 1px solid var(--border-light);
    }
    .highlight-col {
      background: #F0F9FF;
      border-left: 4px solid var(--accent-cyan);
      font-weight: 500;
    }
    @media (max-width: 768px) {
      .comparison-table, .comparison-table thead, .comparison-table tbody, .comparison-table th, .comparison-table td, .comparison-table tr {
        display: block;
      }
      .comparison-table thead { display: none; }
      .comparison-table tr {
        margin-bottom: 16px;
        background: white;
        border-radius: var(--radius-md);
        box-shadow: var(--shadow-sm);
      }
      .comparison-table td {
        display: flex;
        justify-content: space-between;
        padding: 12px;
      }
    }
    
    /* FAQ 手风琴 */
    .faq-item {
      background: white;
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      margin-bottom: 12px;
      overflow: hidden;
    }
    .faq-question {
      padding: 18px 24px;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
      background: white;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: #F1F5F9;
      padding: 0 24px;
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding: 16px 24px;
    }
    
    /* 表单 */
    .contact-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
      margin-top: 24px;
    }
    .input-field {
      width: 100%;
      padding: 14px 16px;
      border: 1px solid #CBD5E1;
      border-radius: var(--radius-md);
      margin-bottom: 16px;
      transition: border var(--transition);
    }
    .input-field:focus {
      outline: none;
      border-color: var(--accent-cyan);
      box-shadow: 0 0 0 3px rgba(0,194,209,0.2);
    }
    .trust-badges {
      display: flex;
      flex-wrap: wrap;
      gap: 16px;
    }
    .badge-placeholder {
      width: 80px;
      height: 80px;
      background: #F1F5F9;
      border: 2px dashed #CBD5E1;
      border-radius: var(--radius-md);
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--text-muted);
      font-size: 12px;
    }
    @media (max-width: 768px) {
      .contact-grid {
        grid-template-columns: 1fr;
      }
    }
    
    /* 页脚 */
    footer {
      background: var(--primary-deep);
      color: var(--text-on-dark);
      padding: 60px 0 20px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr;
      gap: 40px;
      margin-bottom: 40px;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }