:root {
      --primary: #4f46e5;
      --primary-gradient: linear-gradient(135deg, #6366f1 0%, #a855f7 50%, #ec4899 100%);
      --rainbow-subtle: linear-gradient(90deg, rgba(239,68,68,0.06), rgba(245,158,11,0.06), rgba(16,185,129,0.06), rgba(59,130,246,0.06), rgba(139,92,246,0.06));
      --text-main: #0f172a;
      --text-muted: #475569;
      --bg-body: #f8fafc;
      --bg-card: #ffffff;
      --border-color: #e2e8f0;
      --shadow-sm: 0 2px 8px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 24px rgba(149, 157, 165, 0.12);
      --shadow-lg: 0 16px 32px rgba(99, 102, 241, 0.15);
      --radius-lg: 16px;
      --radius-md: 10px;
      --radius-sm: 6px;
      --container-max: 1200px;
    }

    * {
      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(--bg-body);
      color: var(--text-main);
      line-height: 1.6;
    }

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

    a {
      color: var(--primary);
      text-decoration: none;
      transition: all 0.25s ease;
    }
    a:hover {
      opacity: 0.85;
    }

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

    /* 顶部导航 */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 1000;
      background: rgba(255, 255, 255, 0.92);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid rgba(226, 232, 240, 0.8);
      box-shadow: 0 2px 10px rgba(0,0,0,0.03);
    }
    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .brand-wrap {
      display: flex;
      align-items: center;
      gap: 12px;
    }
    .ai-page-logo {
      height: 40px;
      width: auto;
      object-fit: contain;
    }
    .nav-menu {
      display: flex;
      align-items: center;
      gap: 20px;
      list-style: none;
    }
    .nav-menu a {
      font-size: 15px;
      font-weight: 500;
      color: #334155;
    }
    .nav-menu a:hover {
      color: var(--primary);
    }
    .nav-actions {
      display: flex;
      align-items: center;
      gap: 12px;
    }

    /* 通用按钮 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 10px 22px;
      font-size: 15px;
      font-weight: 600;
      border-radius: var(--radius-md);
      cursor: pointer;
      border: 1px solid transparent;
      transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
      white-space: nowrap;
    }
    .btn-primary {
      background: var(--primary-gradient);
      color: #ffffff !important;
      box-shadow: 0 4px 14px rgba(99, 102, 241, 0.35);
    }
    .btn-primary:hover {
      transform: translateY(-2px);
      box-shadow: 0 6px 20px rgba(99, 102, 241, 0.45);
    }
    .btn-outline {
      border-color: #cbd5e1;
      background: #ffffff;
      color: #334155 !important;
    }
    .btn-outline:hover {
      border-color: var(--primary);
      color: var(--primary) !important;
      background: #f1f5f9;
    }

    /* 移动端菜单按钮 */
    .mobile-nav-toggle {
      display: none;
      background: none;
      border: none;
      font-size: 24px;
      cursor: pointer;
      color: var(--text-main);
    }

    /* 首屏 Hero - 禁止出现任何图片 */
    .hero-section {
      padding: 80px 0 60px;
      background: radial-gradient(circle at 10% 20%, rgba(99, 102, 241, 0.08) 0%, transparent 40%),
                  radial-gradient(circle at 90% 80%, rgba(236, 72, 153, 0.08) 0%, transparent 40%),
                  radial-gradient(circle at 50% 50%, rgba(16, 185, 129, 0.05) 0%, transparent 60%);
      text-align: center;
      position: relative;
    }
    .hero-badge {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      padding: 6px 16px;
      border-radius: 30px;
      background: rgba(255, 255, 255, 0.9);
      border: 1px solid #e2e8f0;
      box-shadow: var(--shadow-sm);
      font-size: 14px;
      font-weight: 600;
      color: #4f46e5;
      margin-bottom: 24px;
    }
    .hero-title {
      font-size: 2.5rem;
      font-weight: 800;
      line-height: 1.25;
      color: #0f172a;
      margin-bottom: 20px;
      letter-spacing: -0.5px;
    }
    .hero-title .highlight-text {
      background: linear-gradient(135deg, #4f46e5, #ec4899);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }
    .hero-desc {
      font-size: 1.15rem;
      color: #475569;
      max-width: 800px;
      margin: 0 auto 36px;
      line-height: 1.7;
    }
    .hero-buttons {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 16px;
      flex-wrap: wrap;
      margin-bottom: 48px;
    }
    .hero-stats {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
      gap: 20px;
      margin-top: 20px;
    }
    .stat-card {
      background: #ffffff;
      border: 1px solid #f1f5f9;
      border-radius: var(--radius-md);
      padding: 20px;
      box-shadow: var(--shadow-sm);
      border-top: 4px solid var(--primary);
    }
    .stat-card:nth-child(2) { border-top-color: #ec4899; }
    .stat-card:nth-child(3) { border-top-color: #10b981; }
    .stat-card:nth-child(4) { border-top-color: #f59e0b; }
    .stat-number {
      font-size: 1.8rem;
      font-weight: 800;
      color: #0f172a;
    }
    .stat-label {
      font-size: 0.9rem;
      color: #64748b;
    }

    /* 板块通用头部 */
    .section-padding {
      padding: 70px 0;
    }
    .section-padding:nth-child(even) {
      background: #ffffff;
    }
    .section-header {
      text-align: center;
      max-width: 760px;
      margin: 0 auto 48px;
    }
    .section-tag {
      font-size: 13px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 1px;
      color: #6366f1;
      background: rgba(99, 102, 241, 0.1);
      padding: 4px 12px;
      border-radius: 20px;
      display: inline-block;
      margin-bottom: 12px;
    }
    .section-title {
      font-size: 2rem;
      font-weight: 800;
      color: #0f172a;
      margin-bottom: 14px;
    }
    .section-desc {
      font-size: 1.05rem;
      color: #64748b;
    }

    /* 卡片网格布局 */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
      gap: 24px;
    }
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
      gap: 20px;
    }

    .feature-card {
      background: var(--bg-card);
      border-radius: var(--radius-lg);
      padding: 28px;
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
      transition: all 0.3s ease;
      position: relative;
      overflow: hidden;
    }
    .feature-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-lg);
      border-color: #c7d2fe;
    }
    .feature-icon {
      width: 52px;
      height: 52px;
      border-radius: 12px;
      background: var(--primary-gradient);
      display: flex;
      align-items: center;
      justify-content: center;
      color: #fff;
      font-size: 24px;
      margin-bottom: 20px;
    }
    .feature-title {
      font-size: 1.25rem;
      font-weight: 700;
      color: #0f172a;
      margin-bottom: 10px;
    }
    .feature-desc {
      font-size: 0.95rem;
      color: #475569;
      line-height: 1.6;
    }

    /* 标签云与模型组件 */
    .tag-cloud {
      display: flex;
      flex-wrap: wrap;
      gap: 10px;
      justify-content: center;
      margin-top: 24px;
    }
    .tag-badge {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      padding: 6px 14px;
      border-radius: 20px;
      font-size: 14px;
      font-weight: 600;
      color: #334155;
      box-shadow: 0 1px 3px rgba(0,0,0,0.05);
      transition: all 0.2s ease;
    }
    .tag-badge:hover {
      background: var(--primary-gradient);
      color: #ffffff;
      border-color: transparent;
      transform: translateY(-2px);
    }

    /* 对比评测表格 */
    .table-container {
      width: 100%;
      overflow-x: auto;
      background: #ffffff;
      border-radius: var(--radius-lg);
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-md);
    }
    .custom-table {
      width: 100%;
      border-collapse: collapse;
      text-align: left;
      min-width: 700px;
    }
    .custom-table th, .custom-table td {
      padding: 16px 20px;
      border-bottom: 1px solid #f1f5f9;
      font-size: 0.95rem;
    }
    .custom-table th {
      background: #f8fafc;
      font-weight: 700;
      color: #1e293b;
    }
    .custom-table tr:hover {
      background: #faf5ff;
    }
    .highlight-col {
      background: #f0fdf4 !important;
      font-weight: 600;
      color: #166534;
    }

    /* 评价与案例 */
    .review-card {
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-lg);
      padding: 24px;
      box-shadow: var(--shadow-sm);
    }
    .review-user {
      display: flex;
      align-items: center;
      gap: 14px;
      margin-bottom: 14px;
    }
    .user-avatar-text {
      width: 44px;
      height: 44px;
      border-radius: 50%;
      background: var(--primary-gradient);
      color: #ffffff;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      font-size: 16px;
    }
    .user-name {
      font-weight: 700;
      color: #0f172a;
    }
    .user-role {
      font-size: 13px;
      color: #64748b;
    }
    .stars {
      color: #f59e0b;
      font-size: 14px;
      margin-bottom: 8px;
    }

    /* FAQ 折叠面板 */
    .faq-list {
      display: flex;
      flex-direction: column;
      gap: 16px;
      max-width: 900px;
      margin: 0 auto;
    }
    .faq-item {
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
    }
    .faq-question {
      padding: 18px 24px;
      font-size: 1.05rem;
      font-weight: 700;
      color: #0f172a;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      background: #ffffff;
    }
    .faq-question::after {
      content: "+";
      font-size: 20px;
      font-weight: 400;
      color: #6366f1;
      transition: transform 0.25s ease;
    }
    .faq-item.active .faq-question::after {
      content: "-";
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s cubic-bezier(0, 1, 0, 1);
      background: #f8fafc;
      padding: 0 24px;
    }
    .faq-item.active .faq-answer {
      max-height: 500px;
      transition: max-height 0.3s ease-in-out;
      padding: 16px 24px 20px;
      border-top: 1px solid #f1f5f9;
    }

    /* 表单组件 */
    .contact-form-wrap {
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-lg);
      padding: 36px;
      box-shadow: var(--shadow-md);
    }
    .form-group {
      margin-bottom: 20px;
    }
    .form-label {
      display: block;
      font-size: 14px;
      font-weight: 600;
      color: #334155;
      margin-bottom: 8px;
    }
    .form-input, .form-select, .form-textarea {
      width: 100%;
      padding: 12px 16px;
      font-size: 15px;
      border: 1px solid #cbd5e1;
      border-radius: var(--radius-md);
      outline: none;
      transition: border-color 0.2s;
    }
    .form-input:focus, .form-select:focus, .form-textarea:focus {
      border-color: #6366f1;
      box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
    }
    .form-textarea {
      min-height: 120px;
      resize: vertical;
    }

    /* 文章列表样式 */
    .article-links-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
      gap: 16px;
    }
    .article-item {
      background: #ffffff;
      border: 1px solid var(--border-color);
      padding: 16px 20px;
      border-radius: var(--radius-md);
      font-size: 15px;
      display: flex;
      align-items: center;
      justify-content: space-between;
    }

    /* 页脚 */
    .site-footer {
      background: #0f172a;
      color: #94a3b8;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
      gap: 32px;
      margin-bottom: 40px;
    }
    .footer-col h4 {
      color: #ffffff;
      font-size: 1.1rem;
      margin-bottom: 18px;
    }
    .footer-col ul {
      list-style: none;
    }
    .footer-col ul li {
      margin-bottom: 10px;
    }
    .footer-col ul li a {
      color: #94a3b8;
    }
    .footer-col ul li a:hover {
      color: #ffffff;
    }
    .friendly-links-wrap {
      border-top: 1px solid #1e293b;
      padding-top: 24px;
      margin-top: 24px;
    }
    .friendly-links {
      display: flex;
      flex-wrap: wrap;
      gap: 14px;
    }
    .friendly-links a {
      color: #64748b;
      font-size: 14px;
    }
    .friendly-links a:hover {
      color: #38bdf8;
    }
    .footer-bottom {
      border-top: 1px solid #1e293b;
      padding-top: 24px;
      text-align: center;
      font-size: 14px;
    }

    /* 浮动客服悬浮窗 */
    .float-kefu-btn {
      position: fixed;
      right: 24px;
      bottom: 24px;
      z-index: 999;
      background: var(--primary-gradient);
      color: #fff;
      padding: 12px 20px;
      border-radius: 30px;
      box-shadow: 0 8px 24px rgba(99, 102, 241, 0.4);
      display: flex;
      align-items: center;
      gap: 8px;
      cursor: pointer;
      font-weight: 600;
    }
    .kefu-modal {
      display: none;
      position: fixed;
      right: 24px;
      bottom: 80px;
      z-index: 1000;
      background: #ffffff;
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-lg);
      padding: 20px;
      width: 240px;
      text-align: center;
      border: 1px solid var(--border-color);
    }
    .kefu-modal img {
      max-width: 100%;
      height: auto;
      border-radius: 8px;
      margin-bottom: 10px;
    }

    /* 响应式适配 */
    @media (max-width: 768px) {
      .nav-menu {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        right: 0;
        background: #ffffff;
        flex-direction: column;
        padding: 20px;
        border-bottom: 1px solid #e2e8f0;
        box-shadow: var(--shadow-md);
      }
      .nav-menu.active {
        display: flex;
      }
      .mobile-nav-toggle {
        display: block;
      }
      .hero-title {
        font-size: 1.8rem;
      }
      .section-title {
        font-size: 1.5rem;
      }
      .btn {
        width: 100%;
      }
    }