:root {
      --primary: #1d4ed8;
      --primary-hover: #1e40af;
      --primary-light: #eff6ff;
      --accent: #0284c7;
      --accent-bright: #06b6d4;
      --dark: #0f172a;
      --slate: #334155;
      --muted: #64748b;
      --light-bg: #f8fafc;
      --card-bg: #ffffff;
      --border-color: #e2e8f0;
      --shadow-sm: 0 2px 4px rgba(15, 23, 42, 0.05);
      --shadow-md: 0 10px 25px -5px rgba(29, 78, 216, 0.08);
      --shadow-lg: 0 20px 35px -10px rgba(15, 23, 42, 0.12);
      --radius: 12px;
      --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    }

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

    html {
      scroll-behavior: smooth;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
      background-color: var(--light-bg);
      color: var(--dark);
      line-height: 1.6;
    }

    body {
      overflow-x: hidden;
      background-color: var(--light-bg);
    }

    a {
      color: var(--primary);
      text-decoration: none;
      transition: var(--transition);
    }

    a:hover {
      color: var(--primary-hover);
    }

    .container {
      width: 100%;
      max-width: 1240px;
      margin: 0 auto;
      padding: 0 20px;
    }

    /* 顶部导航 */
    .header {
      position: sticky;
      top: 0;
      z-index: 1000;
      background: rgba(255, 255, 255, 0.95);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
    }

    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }

    .brand-area {
      display: flex;
      align-items: center;
      gap: 12px;
    }

    .ai-page-logo {
      height: 42px;
      width: auto;
      object-fit: contain;
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 0;
      list-style: none;
    }

    .nav-links li a {
      display: inline-block;
      padding: 8px 12px;
      font-size: 14px;
      font-weight: 500;
      color: var(--slate);
      border-radius: 6px;
    }

    .nav-links li a:hover,
    .nav-links li a.active {
      color: var(--primary);
      background-color: var(--primary-light);
    }

    .nav-actions {
      display: flex;
      align-items: center;
      gap: 12px;
    }

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 10px 22px;
      font-size: 15px;
      font-weight: 600;
      border-radius: 8px;
      cursor: pointer;
      border: 1px solid transparent;
      transition: var(--transition);
      white-space: nowrap;
    }

    .btn-primary {
      background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 100%);
      color: #ffffff;
      box-shadow: 0 4px 14px rgba(29, 78, 216, 0.3);
    }

    .btn-primary:hover {
      background: linear-gradient(135deg, var(--primary-hover) 0%, #0369a1 100%);
      color: #ffffff;
      transform: translateY(-2px);
      box-shadow: 0 6px 20px rgba(29, 78, 216, 0.4);
    }

    .btn-outline {
      background-color: transparent;
      border-color: var(--primary);
      color: var(--primary);
    }

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

    .mobile-menu-btn {
      display: none;
      background: none;
      border: none;
      font-size: 24px;
      color: var(--dark);
      cursor: pointer;
    }

    /* 首屏 HERO（严禁图片） */
    .hero-section {
      padding: 80px 0 60px;
      background: radial-gradient(circle at 50% 20%, #eff6ff 0%, #f8fafc 70%);
      border-bottom: 1px solid var(--border-color);
      text-align: center;
      position: relative;
    }

    .hero-badge {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      padding: 6px 16px;
      background: #dbeafe;
      color: var(--primary);
      font-size: 14px;
      font-weight: 600;
      border-radius: 50px;
      margin-bottom: 24px;
      border: 1px solid #bfdbfe;
    }

    .hero-title {
      font-size: 34px;
      font-weight: 800;
      color: var(--dark);
      letter-spacing: -0.5px;
      margin-bottom: 20px;
      line-height: 1.25;
    }

    .hero-subtitle {
      font-size: 18px;
      color: var(--slate);
      max-width: 860px;
      margin: 0 auto 36px;
      line-height: 1.6;
    }

    .hero-cta-group {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 16px;
      margin-bottom: 50px;
      flex-wrap: wrap;
    }

    .hero-stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 20px;
      margin-top: 20px;
    }

    .hero-stat-card {
      background: var(--card-bg);
      padding: 24px 16px;
      border-radius: var(--radius);
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }

    .hero-stat-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
      border-color: #93c5fd;
    }

    .stat-number {
      font-size: 32px;
      font-weight: 800;
      color: var(--primary);
      line-height: 1;
      margin-bottom: 8px;
    }

    .stat-label {
      font-size: 14px;
      color: var(--muted);
    }

    /* 板块通用 */
    .section-padding {
      padding: 80px 0;
    }

    .section-header {
      text-align: center;
      max-width: 760px;
      margin: 0 auto 50px;
    }

    .section-tag {
      font-size: 13px;
      font-weight: 700;
      text-transform: uppercase;
      color: var(--accent);
      letter-spacing: 1px;
      margin-bottom: 8px;
      display: block;
    }

    .section-title {
      font-size: 32px;
      font-weight: 700;
      color: var(--dark);
      margin-bottom: 16px;
    }

    .section-desc {
      font-size: 16px;
      color: var(--muted);
    }

    /* 网格卡片 */
    .grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px; }
    .grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
    .grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }

    .feature-card {
      background: var(--card-bg);
      padding: 30px;
      border-radius: var(--radius);
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      display: flex;
      flex-direction: column;
      height: 100%;
    }

    .feature-card:hover {
      box-shadow: var(--shadow-md);
      border-color: #bfdbfe;
      transform: translateY(-3px);
    }

    .feature-icon {
      width: 48px;
      height: 48px;
      border-radius: 10px;
      background: var(--primary-light);
      color: var(--primary);
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 22px;
      font-weight: 700;
      margin-bottom: 20px;
    }

    .feature-title {
      font-size: 20px;
      font-weight: 700;
      margin-bottom: 12px;
      color: var(--dark);
    }

    .feature-desc {
      font-size: 14px;
      color: var(--slate);
      line-height: 1.6;
      flex-grow: 1;
    }

    .tag-cloud {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
      margin-top: 16px;
    }

    .chip {
      background: var(--light-bg);
      border: 1px solid var(--border-color);
      padding: 4px 10px;
      border-radius: 20px;
      font-size: 12px;
      color: var(--slate);
    }

    /* 包含图片的图文模块（非首屏） */
    .media-card {
      background: var(--card-bg);
      border-radius: var(--radius);
      border: 1px solid var(--border-color);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }

    .media-card:hover {
      box-shadow: var(--shadow-md);
    }

    .media-img-wrapper {
      width: 100%;
      overflow: hidden;
      background: #f1f5f9;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .ai-page-image {
      width: 100%;
      height: auto;
      object-fit: cover;
      display: block;
      transition: transform 0.5s ease;
    }

    .media-card:hover .ai-page-image {
      transform: scale(1.03);
    }

    .media-content {
      padding: 24px;
    }

    /* 对比表格 */
    .table-wrapper {
      background: var(--card-bg);
      border-radius: var(--radius);
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
      overflow-x: auto;
    }

    .comp-table {
      width: 100%;
      border-collapse: collapse;
      text-align: left;
      min-width: 700px;
    }

    .comp-table th, .comp-table td {
      padding: 16px 20px;
      border-bottom: 1px solid var(--border-color);
      font-size: 14px;
    }

    .comp-table th {
      background: #f8fafc;
      font-weight: 700;
      color: var(--dark);
    }

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

    .highlight-cell {
      background: var(--primary-light);
      color: var(--primary);
      font-weight: 700;
    }

    .score-badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
      padding: 6px 14px;
      background: linear-gradient(135deg, #fbbf24 0%, #f59e0b 100%);
      color: #ffffff;
      font-size: 16px;
      font-weight: 800;
      border-radius: 20px;
      margin-bottom: 16px;
    }

    /* 折叠面板 FAQ */
    .faq-list {
      display: flex;
      flex-direction: column;
      gap: 16px;
      max-width: 900px;
      margin: 0 auto;
    }

    .faq-item {
      background: var(--card-bg);
      border: 1px solid var(--border-color);
      border-radius: var(--radius);
      overflow: hidden;
      transition: var(--transition);
    }

    .faq-header {
      padding: 20px 24px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      cursor: pointer;
      font-weight: 600;
      color: var(--dark);
      font-size: 16px;
    }

    .faq-header:hover {
      background-color: var(--primary-light);
    }

    .faq-icon {
      font-size: 18px;
      transition: transform 0.3s ease;
      color: var(--primary);
    }

    .faq-item.active .faq-icon {
      transform: rotate(180deg);
    }

    .faq-body {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      padding: 0 24px;
      color: var(--slate);
      font-size: 14px;
      line-height: 1.6;
      background: #ffffff;
    }

    .faq-item.active .faq-body {
      max-height: 300px;
      padding: 0 24px 20px;
      border-top: 1px dashed var(--border-color);
    }

    /* 评论卡片 */
    .review-card {
      background: var(--card-bg);
      border-radius: var(--radius);
      border: 1px solid var(--border-color);
      padding: 24px;
      box-shadow: var(--shadow-sm);
      display: flex;
      flex-direction: column;
      justify-content: space-between;
    }

    .review-stars {
      color: #f59e0b;
      margin-bottom: 12px;
      font-size: 14px;
    }

    .review-text {
      font-size: 14px;
      color: var(--slate);
      line-height: 1.6;
      margin-bottom: 20px;
    }

    .review-author {
      display: flex;
      align-items: center;
      gap: 12px;
      border-top: 1px solid var(--border-color);
      padding-top: 12px;
    }

    .author-avatar {
      width: 40px;
      height: 40px;
      border-radius: 50%;
      background: var(--primary-light);
      color: var(--primary);
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
    }

    .author-info h4 {
      font-size: 14px;
      font-weight: 700;
      color: var(--dark);
    }

    .author-info p {
      font-size: 12px;
      color: var(--muted);
    }

    /* 表单区块 */
    .form-container {
      background: var(--card-bg);
      border-radius: var(--radius);
      border: 1px solid var(--border-color);
      padding: 40px;
      box-shadow: var(--shadow-md);
      max-width: 800px;
      margin: 0 auto;
    }

    .form-group {
      margin-bottom: 20px;
    }

    .form-label {
      display: block;
      font-size: 14px;
      font-weight: 600;
      color: var(--dark);
      margin-bottom: 8px;
    }

    .form-input, .form-select, .form-textarea {
      width: 100%;
      padding: 12px 16px;
      border: 1px solid var(--border-color);
      border-radius: 8px;
      font-size: 14px;
      color: var(--dark);
      background-color: var(--light-bg);
      transition: var(--transition);
    }

    .form-input:focus, .form-select:focus, .form-textarea:focus {
      outline: none;
      border-color: var(--primary);
      background-color: #ffffff;
      box-shadow: 0 0 0 3px rgba(29, 78, 216, 0.1);
    }

    /* 页脚 */
    .footer {
      background: var(--dark);
      color: #94a3b8;
      padding: 60px 0 30px;
      border-top: 1px solid #1e293b;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      margin-bottom: 40px;
    }

    .footer-brand h3 {
      color: #ffffff;
      font-size: 20px;
      margin-bottom: 16px;
    }

    .footer-brand p {
      font-size: 14px;
      line-height: 1.6;
      margin-bottom: 20px;
    }

    .footer-links h4 {
      color: #ffffff;
      font-size: 16px;
      margin-bottom: 16px;
    }

    .footer-links ul {
      list-style: none;
    }

    .footer-links ul li {
      margin-bottom: 10px;
    }

    .footer-links ul li a {
      color: #94a3b8;
      font-size: 14px;
    }

    .footer-links ul li a:hover {
      color: #ffffff;
    }

    .friendship-links {
      border-top: 1px solid #1e293b;
      padding-top: 24px;
      margin-top: 24px;
      display: flex;
      flex-wrap: wrap;
      gap: 16px;
      align-items: center;
    }

    .friendship-links span {
      color: #ffffff;
      font-size: 14px;
      font-weight: 600;
    }

    .friendship-links a {
      color: #94a3b8;
      font-size: 13px;
    }

    .friendship-links a:hover {
      color: #ffffff;
    }

    .footer-bottom {
      border-top: 1px solid #1e293b;
      padding-top: 24px;
      text-align: center;
      font-size: 13px;
    }

    /* 浮动客服 */
    .floating-widget {
      position: fixed;
      right: 20px;
      bottom: 20px;
      z-index: 999;
      display: flex;
      flex-direction: column;
      gap: 12px;
    }

    .float-btn {
      width: 48px;
      height: 48px;
      border-radius: 50%;
      background: var(--primary);
      color: #ffffff;
      display: flex;
      align-items: center;
      justify-content: center;
      box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
      cursor: pointer;
      transition: var(--transition);
    }

    .float-btn:hover {
      transform: scale(1.1);
      background: var(--primary-hover);
    }

    .kefu-popup {
      display: none;
      position: absolute;
      bottom: 60px;
      right: 0;
      background: #ffffff;
      border: 1px solid var(--border-color);
      padding: 16px;
      border-radius: 12px;
      box-shadow: var(--shadow-lg);
      width: 200px;
      text-align: center;
    }

    .kefu-popup img {
      width: 100%;
      height: auto;
      border-radius: 8px;
    }

    .floating-widget:hover .kefu-popup {
      display: block;
    }

    /* 响应式调整 */
    @media (max-width: 992px) {
      .grid-4, .hero-stats-grid { grid-template-columns: repeat(2, 1fr); }
      .grid-3 { grid-template-columns: repeat(2, 1fr); }
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }

    @media (max-width: 768px) {
      .mobile-menu-btn { display: block; }
      .nav-links {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        width: 100%;
        background: #ffffff;
        flex-direction: column;
        padding: 20px;
        border-bottom: 1px solid var(--border-color);
        box-shadow: var(--shadow-md);
      }
      .nav-links.show { display: flex; }
      .hero-title { font-size: 26px; }
      .grid-2, .grid-3, .grid-4, .hero-stats-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
      .form-container { padding: 24px; }
    }