:root {
      --primary-color: #ff5722;
      --primary-hover: #f4511e;
      --primary-gradient: linear-gradient(135deg, #ff6b00 0%, #ff3d00 100%);
      --accent-color: #ff9800;
      --bg-warm: #fffbf9;
      --bg-card: #ffffff;
      --text-main: #1f2937;
      --text-muted: #6b7280;
      --border-color: #ffe6dc;
      --shadow-sm: 0 2px 8px rgba(255, 87, 34, 0.06);
      --shadow-md: 0 10px 25px rgba(255, 87, 34, 0.1);
      --shadow-lg: 0 20px 40px rgba(0, 0, 0, 0.08);
      --container-max: 1200px;
    }

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

    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
      background-color: var(--bg-warm);
      color: var(--text-main);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }

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

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

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

    /* 顶部导航栏 */
    .header {
      background: rgba(255, 255, 255, 0.95);
      backdrop-filter: blur(10px);
      position: sticky;
      top: 0;
      z-index: 1000;
      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: 16px;
    }

    .ai-page-logo {
      height: 40px;
      width: auto;
      display: block;
    }

    .nav-menu {
      display: flex;
      align-items: center;
      gap: 24px;
      list-style: none;
    }

    .nav-menu a {
      color: var(--text-main);
      font-weight: 500;
      font-size: 15px;
    }

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

    .header-actions {
      display: flex;
      align-items: center;
      gap: 16px;
    }

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 10px 24px;
      border-radius: 50px;
      font-size: 15px;
      font-weight: 600;
      cursor: pointer;
      border: none;
      transition: all 0.3s ease;
      text-align: center;
    }

    .btn-primary {
      background: var(--primary-gradient);
      color: #ffffff !important;
      box-shadow: 0 4px 14px rgba(255, 87, 34, 0.35);
    }

    .btn-primary:hover {
      transform: translateY(-2px);
      box-shadow: 0 6px 20px rgba(255, 87, 34, 0.45);
    }

    .btn-secondary {
      background: #fff0eb;
      color: var(--primary-color) !important;
      border: 1px solid #ffd5c6;
    }

    .btn-secondary:hover {
      background: #ffe5dc;
    }

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

    /* Hero 首屏 - 严禁图片 */
    .hero-section {
      padding: 80px 0 60px;
      background: linear-gradient(180deg, #fff0eb 0%, var(--bg-warm) 100%);
      text-align: center;
      position: relative;
      overflow: hidden;
    }

    .hero-badge {
      display: inline-block;
      padding: 6px 18px;
      background: #ffe5dc;
      color: var(--primary-color);
      border-radius: 30px;
      font-size: 14px;
      font-weight: 600;
      margin-bottom: 20px;
      letter-spacing: 0.5px;
    }

    .hero-title {
      font-size: 38px;
      line-height: 1.25;
      font-weight: 800;
      color: #111827;
      margin-bottom: 20px;
      letter-spacing: -0.5px;
    }

    .hero-desc {
      font-size: 18px;
      color: var(--text-muted);
      max-width: 800px;
      margin: 0 auto 36px;
      line-height: 1.7;
    }

    .hero-actions {
      display: flex;
      justify-content: center;
      gap: 16px;
      margin-bottom: 50px;
      flex-wrap: wrap;
    }

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

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

    .metric-number {
      font-size: 32px;
      font-weight: 800;
      color: var(--primary-color);
      margin-bottom: 4px;
    }

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

    /* 通用 Section 布局 */
    .section-padding {
      padding: 70px 0;
    }

    .section-header {
      text-align: center;
      margin-bottom: 48px;
    }

    .section-subtitle {
      color: var(--primary-color);
      font-weight: 700;
      font-size: 14px;
      text-transform: uppercase;
      letter-spacing: 1px;
      margin-bottom: 8px;
    }

    .section-title {
      font-size: 30px;
      font-weight: 800;
      color: var(--text-main);
    }

    .section-intro {
      font-size: 16px;
      color: var(--text-muted);
      max-width: 680px;
      margin: 12px auto 0;
    }

    /* 网格与卡片 */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }

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

    .grid-2 {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 32px;
    }

    .card {
      background: var(--bg-card);
      border-radius: 16px;
      padding: 30px;
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
      transition: all 0.3s ease;
      height: 100%;
      display: flex;
      flex-direction: column;
    }

    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
      border-color: #ffd0bf;
    }

    .card-icon {
      width: 48px;
      height: 48px;
      background: #fff0eb;
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 22px;
      color: var(--primary-color);
      margin-bottom: 20px;
      font-weight: bold;
    }

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

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

    /* 标签云 - 核心模型生态 */
    .model-tags {
      display: flex;
      flex-wrap: wrap;
      gap: 12px;
      justify-content: center;
      margin-top: 24px;
    }

    .model-tag {
      background: #ffffff;
      border: 1px solid #ffd8c9;
      color: var(--text-main);
      padding: 8px 18px;
      border-radius: 20px;
      font-size: 14px;
      font-weight: 600;
      box-shadow: var(--shadow-sm);
      transition: all 0.2s ease;
    }

    .model-tag:hover {
      background: var(--primary-color);
      color: #ffffff;
      border-color: var(--primary-color);
    }

    /* 流程步骤 */
    .process-steps {
      display: grid;
      grid-template-columns: repeat(5, 1fr);
      gap: 16px;
      margin-top: 20px;
    }

    .step-card {
      background: var(--bg-card);
      padding: 24px 16px;
      border-radius: 12px;
      border: 1px solid var(--border-color);
      text-align: center;
      position: relative;
    }

    .step-num {
      width: 32px;
      height: 32px;
      background: var(--primary-gradient);
      color: white;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: bold;
      margin: 0 auto 12px;
    }

    /* 对比表格 */
    .comparison-badge {
      background: linear-gradient(135deg, #fff3e0 0%, #ffe0b2 100%);
      border: 1px solid #ffe0b2;
      border-radius: 16px;
      padding: 20px;
      margin-bottom: 24px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      flex-wrap: wrap;
      gap: 16px;
    }

    .score-title {
      font-size: 18px;
      font-weight: 700;
      color: #e65100;
    }

    .score-rating {
      font-size: 24px;
      font-weight: 800;
      color: var(--primary-color);
    }

    .table-container {
      width: 100%;
      overflow-x: auto;
      background: var(--bg-card);
      border-radius: 16px;
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
    }

    .custom-table {
      width: 100%;
      border-collapse: collapse;
      text-align: left;
      font-size: 15px;
    }

    .custom-table th, .custom-table td {
      padding: 16px 20px;
      border-bottom: 1px solid #f0f0f0;
    }

    .custom-table th {
      background: #fff5f0;
      color: var(--text-main);
      font-weight: 700;
    }

    .custom-table tr:hover {
      background: #fffbf9;
    }

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

    /* 图片呈现区 (精简与稳定) */
    .ai-page-image {
      border-radius: 12px;
      box-shadow: var(--shadow-sm);
      display: block;
      width: 100%;
      height: auto;
    }

    /* 培训课程卡片 */
    .course-card {
      border-left: 4px solid var(--primary-color);
    }

    /* 评论卡片 */
    .review-user {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-top: 16px;
    }

    .avatar-placeholder {
      width: 40px;
      height: 40px;
      background: #ffe3d8;
      color: var(--primary-color);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
    }

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

    .faq-item {
      background: var(--bg-card);
      border-radius: 12px;
      border: 1px solid var(--border-color);
      overflow: hidden;
    }

    .faq-question {
      padding: 20px 24px;
      font-size: 16px;
      font-weight: 700;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      user-select: none;
    }

    .faq-answer {
      padding: 0 24px 20px;
      font-size: 14px;
      color: var(--text-muted);
      display: none;
      line-height: 1.7;
    }

    .faq-item.active .faq-answer {
      display: block;
    }

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

    .faq-toggle {
      transition: transform 0.3s ease;
      color: var(--primary-color);
      font-weight: bold;
    }

    /* 表单组件 */
    .form-box {
      background: var(--bg-card);
      padding: 36px;
      border-radius: 20px;
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-md);
    }

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

    .form-label {
      display: block;
      font-weight: 600;
      margin-bottom: 8px;
      font-size: 14px;
    }

    .form-input, .form-select, .form-textarea {
      width: 100%;
      padding: 12px 16px;
      border: 1px solid #d1d5db;
      border-radius: 8px;
      font-size: 14px;
      outline: none;
      transition: border 0.2s ease;
      background: #fafafa;
    }

    .form-input:focus, .form-select:focus, .form-textarea:focus {
      border-color: var(--primary-color);
      background: #ffffff;
    }

    /* 页脚样式 */
    .footer {
      background: #111827;
      color: #9ca3af;
      padding: 60px 0 30px;
      border-top: 1px solid #1f2937;
    }

    .footer-inner {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1.5fr;
      gap: 40px;
      margin-bottom: 40px;
    }

    .footer-brand h3 {
      color: #ffffff;
      font-size: 20px;
      margin-bottom: 12px;
    }

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

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

    .footer-links li {
      margin-bottom: 8px;
    }

    .footer-links a {
      color: #9ca3af;
    }

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

    .friendship-links {
      margin-top: 16px;
      display: flex;
      flex-wrap: wrap;
      gap: 12px;
    }

    .friendship-links a {
      color: #9ca3af;
      font-size: 13px;
    }

    .footer-bottom {
      border-top: 1px solid #1f2937;
      padding-top: 24px;
      text-align: center;
      font-size: 13px;
    }

    /* 浮动客服 */
    .floating-cs {
      position: fixed;
      right: 20px;
      bottom: 30px;
      z-index: 999;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    .cs-btn {
      width: 48px;
      height: 48px;
      background: var(--primary-gradient);
      color: white;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      box-shadow: var(--shadow-md);
      cursor: pointer;
      font-size: 14px;
      font-weight: bold;
    }

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

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

    /* 响应式适配 */
    @media (max-width: 992px) {
      .hero-metrics, .grid-4 {
        grid-template-columns: repeat(2, 1fr);
      }
      .grid-3 {
        grid-template-columns: repeat(2, 1fr);
      }
      .process-steps {
        grid-template-columns: repeat(3, 1fr);
      }
      .footer-inner {
        grid-template-columns: 1fr 1fr;
      }
    }

    @media (max-width: 768px) {
      .nav-menu {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 20px;
        border-bottom: 1px solid var(--border-color);
        box-shadow: var(--shadow-md);
      }

      .nav-menu.active {
        display: flex;
      }

      .mobile-toggle {
        display: block;
      }

      .hero-title {
        font-size: 28px;
      }

      .grid-3, .grid-2, .grid-4, .process-steps {
        grid-template-columns: 1fr;
      }

      .footer-inner {
        grid-template-columns: 1fr;
      }
    }