:root {
      --bg-main: #f8fafc;
      --bg-card: #ffffff;
      --text-main: #0f172a;
      --text-muted: #475569;
      --primary: #4f46e5;
      --primary-hover: #4338ca;
      --rainbow-red: #ef4444;
      --rainbow-orange: #f97316;
      --rainbow-yellow: #eab308;
      --rainbow-green: #10b981;
      --rainbow-cyan: #06b6d4;
      --rainbow-blue: #3b82f6;
      --rainbow-purple: #8b5cf6;
      --border-color: #e2e8f0;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.05);
      --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.08), 0 2px 4px -1px rgba(0,0,0,0.04);
      --shadow-lg: 0 10px 25px -5px rgba(79, 70, 229, 0.12), 0 8px 10px -6px rgba(0,0,0,0.04);
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 20px;
    }

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

    body {
      overflow-x: hidden;
    }

    a {
      color: var(--primary);
      text-decoration: none;
      transition: all 0.2s ease;
    }

    a:hover {
      opacity: 0.85;
    }

    /* Container System */
    .container {
      width: 100%;
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 20px;
    }

    /* Rainbow Accent Bar */
    .rainbow-line {
      height: 4px;
      background: linear-gradient(90deg, 
        var(--rainbow-red), 
        var(--rainbow-orange), 
        var(--rainbow-yellow), 
        var(--rainbow-green), 
        var(--rainbow-cyan), 
        var(--rainbow-blue), 
        var(--rainbow-purple));
      width: 100%;
    }

    /* Header & Navigation */
    header.site-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: 12px;
    }

    .ai-page-logo {
      height: 40px;
      width: auto;
      object-fit: contain;
    }

    .brand-title {
      font-size: 18px;
      font-weight: 700;
      color: var(--text-main);
      letter-spacing: -0.5px;
    }

    /* Strict Rule: .nav-links gap must be 0 */
    .nav-links {
      display: flex;
      align-items: center;
      list-style: none;
      gap: 0;
    }

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

    .nav-links li a:hover {
      color: var(--primary);
      background: #f1f5f9;
    }

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

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 10px 20px;
      font-size: 14px;
      font-weight: 600;
      border-radius: 99px;
      cursor: pointer;
      border: none;
      transition: all 0.25s ease;
      white-space: nowrap;
    }

    .btn-rainbow {
      background: linear-gradient(135deg, #4f46e5, #7c3aed);
      color: #ffffff !important;
      box-shadow: 0 4px 14px rgba(79, 70, 229, 0.35);
    }

    .btn-rainbow:hover {
      transform: translateY(-2px);
      box-shadow: 0 6px 20px rgba(79, 70, 229, 0.45);
      color: #ffffff;
    }

    .btn-outline {
      background: transparent;
      border: 1px solid var(--border-color);
      color: var(--text-main);
    }

    .btn-outline:hover {
      background: #f1f5f9;
      border-color: #cbd5e1;
    }

    /* Section Styling */
    section {
      padding: 70px 0;
      position: relative;
    }

    .section-title-wrap {
      text-align: center;
      margin-bottom: 50px;
    }

    .section-tag {
      display: inline-block;
      padding: 4px 14px;
      font-size: 12px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 1px;
      color: var(--primary);
      background: rgba(79, 70, 229, 0.08);
      border-radius: 20px;
      margin-bottom: 12px;
    }

    .section-title {
      font-size: 32px;
      font-weight: 800;
      color: var(--text-main);
      line-height: 1.3;
    }

    .section-subtitle {
      font-size: 16px;
      color: var(--text-muted);
      margin-top: 10px;
      max-width: 680px;
      margin-left: auto;
      margin-right: auto;
    }

    /* 首屏 HERO SECTION - Strictly NO IMAGES */
    .hero-section {
      padding: 90px 0 80px 0;
      background: radial-gradient(circle at 50% 0%, rgba(99, 102, 241, 0.08) 0%, rgba(248, 250, 252, 0) 70%);
      text-align: center;
    }

    .hero-badge {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      padding: 6px 16px;
      background: #ffffff;
      border: 1px solid #e0e7ff;
      box-shadow: var(--shadow-sm);
      border-radius: 30px;
      font-size: 13px;
      color: #4338ca;
      font-weight: 600;
      margin-bottom: 24px;
    }

    .hero-title {
      font-size: 42px;
      font-weight: 900;
      color: #0f172a;
      line-height: 1.25;
      letter-spacing: -1px;
      margin-bottom: 20px;
    }

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

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

    .hero-btn-main {
      padding: 14px 32px;
      font-size: 16px;
    }

    .hero-stats {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 20px;
      margin-top: 30px;
    }

    .stat-card {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      padding: 24px 16px;
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-sm);
      transition: transform 0.2s;
    }

    .stat-card:hover {
      transform: translateY(-4px);
    }

    .stat-num {
      font-size: 30px;
      font-weight: 800;
      background: linear-gradient(135deg, var(--rainbow-blue), var(--rainbow-purple));
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }

    .stat-label {
      font-size: 13px;
      color: var(--text-muted);
      margin-top: 4px;
    }

    /* Card Grids */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }

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

    .grid-2 {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 30px;
    }

    .feature-card {
      background: var(--bg-card);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 28px;
      box-shadow: var(--shadow-sm);
      transition: all 0.3s ease;
      position: relative;
      overflow: hidden;
    }

    .feature-card::before {
      content: "";
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 3px;
      background: linear-gradient(90deg, var(--rainbow-cyan), var(--rainbow-purple));
      opacity: 0;
      transition: opacity 0.3s ease;
    }

    .feature-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-lg);
      border-color: #cbd5e1;
    }

    .feature-card:hover::before {
      opacity: 1;
    }

    .feature-icon {
      width: 48px;
      height: 48px;
      border-radius: var(--radius-sm);
      background: rgba(79, 70, 229, 0.1);
      color: var(--primary);
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 22px;
      font-weight: bold;
      margin-bottom: 18px;
    }

    .feature-title {
      font-size: 18px;
      font-weight: 700;
      margin-bottom: 10px;
      color: var(--text-main);
    }

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

    /* Model Tags Cloud */
    .model-tags {
      display: flex;
      flex-wrap: wrap;
      gap: 10px;
      justify-content: center;
    }

    .model-tag {
      background: #ffffff;
      border: 1px solid var(--border-color);
      padding: 8px 16px;
      border-radius: 20px;
      font-size: 13px;
      font-weight: 600;
      color: var(--text-main);
      box-shadow: var(--shadow-sm);
      transition: all 0.2s;
    }

    .model-tag:hover {
      border-color: var(--primary);
      color: var(--primary);
      transform: scale(1.05);
    }

    /* Tables */
    .table-container {
      width: 100%;
      overflow-x: auto;
      background: #ffffff;
      border-radius: var(--radius-md);
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
    }

    table.custom-table {
      width: 100%;
      border-collapse: collapse;
      text-align: left;
      font-size: 14px;
    }

    table.custom-table th {
      background: #f8fafc;
      padding: 16px 20px;
      font-weight: 700;
      color: var(--text-main);
      border-bottom: 1px solid var(--border-color);
    }

    table.custom-table td {
      padding: 16px 20px;
      border-bottom: 1px solid var(--border-color);
      color: var(--text-muted);
    }

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

    table.custom-table tr:hover td {
      background: #f1f5f9;
    }

    .badge-highlight {
      display: inline-block;
      padding: 2px 8px;
      background: #dcfce7;
      color: #15803d;
      border-radius: 4px;
      font-size: 12px;
      font-weight: 700;
    }

    /* Comparison Review Box */
    .review-score-box {
      background: linear-gradient(135deg, #1e1b4b, #312e81);
      color: #ffffff;
      border-radius: var(--radius-lg);
      padding: 40px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 30px;
    }

    .score-left {
      max-width: 600px;
    }

    .score-num {
      font-size: 48px;
      font-weight: 900;
      color: #facc15;
    }

    .star-rating {
      color: #facc15;
      font-size: 20px;
      margin-left: 10px;
    }

    /* Step Timeline */
    .process-steps {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 20px;
      position: relative;
    }

    .step-card {
      background: #ffffff;
      padding: 24px;
      border-radius: var(--radius-md);
      border: 1px solid var(--border-color);
      position: relative;
    }

    .step-num {
      font-size: 36px;
      font-weight: 900;
      color: rgba(79, 70, 229, 0.2);
      position: absolute;
      top: 15px;
      right: 20px;
    }

    /* User Reviews */
    .review-card {
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 24px;
      box-shadow: var(--shadow-sm);
    }

    .review-user {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-top: 16px;
    }

    .user-avatar {
      width: 44px;
      height: 44px;
      border-radius: 50%;
      background: linear-gradient(135deg, var(--rainbow-cyan), var(--rainbow-blue));
      color: #fff;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
    }

    /* FAQ Accordion */
    .faq-list {
      max-width: 900px;
      margin: 0 auto;
      display: flex;
      flex-direction: column;
      gap: 14px;
    }

    .faq-item {
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      overflow: hidden;
      transition: border-color 0.2s;
    }

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

    .faq-answer {
      padding: 0 24px 20px 24px;
      color: var(--text-muted);
      font-size: 14px;
      display: none;
      border-top: 1px dashed var(--border-color);
      padding-top: 16px;
    }

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

    .faq-item.active {
      border-color: var(--primary);
    }

    /* Form Design */
    .form-box {
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-lg);
      padding: 40px;
      box-shadow: var(--shadow-lg);
      max-width: 700px;
      margin: 0 auto;
    }

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

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

    .form-control {
      width: 100%;
      padding: 12px 16px;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-sm);
      font-size: 14px;
      outline: none;
      transition: border-color 0.2s;
    }

    .form-control:focus {
      border-color: var(--primary);
    }

    textarea.form-control {
      min-height: 120px;
      resize: vertical;
    }

    /* Article List */
    .article-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 20px;
    }

    .article-card {
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 20px;
    }

    .article-title {
      font-size: 16px;
      font-weight: 700;
      margin-bottom: 8px;
    }

    /* Contact Details */
    .contact-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 30px;
      align-items: center;
    }

    .qr-card {
      text-align: center;
      background: #ffffff;
      padding: 24px;
      border-radius: var(--radius-md);
      border: 1px solid var(--border-color);
    }

    .qr-card img {
      max-width: 180px;
      height: auto;
      border-radius: var(--radius-sm);
      margin-bottom: 12px;
    }

    /* Footer Links & Standard Footer */
    footer.site-footer {
      background: #0f172a;
      color: #94a3b8;
      padding: 60px 0 30px 0;
      font-size: 14px;
    }

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

    .footer-brand {
      color: #ffffff;
      font-size: 18px;
      font-weight: 700;
      margin-bottom: 12px;
    }

    .footer-title {
      color: #ffffff;
      font-size: 15px;
      font-weight: 700;
      margin-bottom: 16px;
    }

    .footer-links-list {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 10px;
    }

    .footer-links-list a {
      color: #94a3b8;
    }

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

    .friend-links-box {
      border-top: 1px solid #1e293b;
      padding-top: 24px;
      margin-top: 30px;
      display: flex;
      flex-wrap: wrap;
      gap: 16px;
      align-items: center;
    }

    .friend-links-box a {
      color: #64748b;
    }

    .friend-links-box a:hover {
      color: #38bdf8;
    }

    .copyright-bar {
      border-top: 1px solid #1e293b;
      padding-top: 24px;
      margin-top: 24px;
      text-align: center;
      color: #64748b;
      font-size: 13px;
    }

    /* Floating Customer Service Widget */
    .float-widget {
      position: fixed;
      right: 24px;
      bottom: 24px;
      z-index: 999;
      display: flex;
      flex-direction: column;
      gap: 12px;
    }

    .float-btn {
      width: 52px;
      height: 52px;
      border-radius: 50%;
      background: var(--primary);
      color: #ffffff;
      display: flex;
      align-items: center;
      justify-content: center;
      box-shadow: var(--shadow-lg);
      cursor: pointer;
      font-weight: bold;
      font-size: 13px;
      transition: transform 0.2s;
    }

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

    /* Responsive adjustments */
    @media (max-width: 1024px) {
      .grid-4, .hero-stats, .process-steps {
        grid-template-columns: repeat(2, 1fr);
      }
      .grid-3, .article-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }

    @media (max-width: 768px) {
      .header-inner {
        flex-direction: column;
        height: auto;
        padding: 12px 0;
        gap: 12px;
      }
      .nav-links {
        flex-wrap: wrap;
        justify-content: center;
      }
      .hero-title {
        font-size: 28px;
      }
      .hero-stats, .grid-4, .grid-3, .grid-2, .process-steps, .article-grid, .contact-grid, .footer-grid {
        grid-template-columns: 1fr;
      }
      .review-score-box {
        flex-direction: column;
        text-align: center;
        gap: 20px;
      }
      .section-title {
        font-size: 24px;
      }
    }