/* roulang page: index */
:root {
      --primary: #0A0E27;
      --accent: #00E5FF;
      --emphasis: #FF4655;
      --bg-light: #F8FAFC;
      --card-white: #FFFFFF;
      --text-primary: #0A0E27;
      --text-body: #334155;
      --text-muted: #64748B;
      --text-on-dark: #FFFFFF;
      --border-light: #E2E8F0;
      --shadow-card: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
      --shadow-hover: 0 10px 25px rgba(0,0,0,0.08);
      --radius-card: 12px;
      --radius-btn: 8px;
      --transition: all 0.25s ease;
      --container: 1200px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      background: var(--bg-light);
      color: var(--text-body);
      line-height: 1.7;
      font-weight: 400;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: var(--container);
      margin: 0 auto;
      padding: 0 24px;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition);
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      font-weight: 600;
      transition: var(--transition);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      border: none;
      outline: none;
      border-radius: var(--radius-btn);
    }
    button:focus-visible, a:focus-visible, .btn:focus-visible {
      outline: 2px solid var(--accent);
      outline-offset: 2px;
    }
    h1, h2, h3, h4 {
      font-weight: 700;
      color: var(--text-primary);
      line-height: 1.2;
    }
    h2 {
      font-size: 36px;
      margin-bottom: 16px;
    }
    .section {
      padding: 100px 0;
    }
    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.95);
      backdrop-filter: blur(10px);
      border-bottom: 1px solid var(--border-light);
      z-index: 100;
      height: 72px;
      display: flex;
      align-items: center;
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
      max-width: var(--container);
      margin: 0 auto;
      padding: 0 24px;
    }
    .logo {
      font-size: 24px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 1px;
      white-space: nowrap;
    }
    .nav-menu {
      display: flex;
      align-items: center;
      gap: 32px;
      list-style: none;
    }
    .nav-menu a {
      color: var(--text-body);
      font-weight: 500;
      font-size: 16px;
      padding: 8px 0;
      position: relative;
    }
    .nav-menu a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent);
      transition: width 0.25s ease;
    }
    .nav-menu a:hover {
      color: var(--accent);
    }
    .nav-menu a:hover::after {
      width: 100%;
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      padding: 4px;
      cursor: pointer;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--primary);
      display: block;
      transition: var(--transition);
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 72px;
      left: 0;
      width: 100%;
      background: var(--primary);
      flex-direction: column;
      padding: 32px;
      gap: 24px;
      z-index: 99;
    }
    .mobile-menu.active {
      display: flex;
    }
    .mobile-menu a {
      color: var(--text-on-dark);
      font-size: 18px;
      font-weight: 500;
      border-bottom: 1px solid rgba(255,255,255,0.1);
      padding-bottom: 12px;
    }
    /* 按钮 */
    .btn-primary {
      background: var(--accent);
      color: var(--primary);
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      box-shadow: 0 4px 10px rgba(0,229,255,0.25);
    }
    .btn-primary:hover {
      background: #00B8D4;
      transform: translateY(-2px);
    }
    .btn-secondary {
      background: transparent;
      border: 2px solid var(--accent);
      color: var(--primary);
 padding: 12px 30px;
    }
    .btn-secondary:hover {
      background: var(--accent);
      color: var(--primary);
      transform: translateY(-2px);
    }
    .btn-emphasis {
      background: var(--emphasis);
      color: white;
      padding: 16px 40px;
      font-weight: 700;
    }
    .btn-emphasis:hover {
      background: #E63946;
      transform: translateY(-2px);
    }
    .btn-outline-light {
      background: transparent;
      border: 2px solid white;
      color: white;
      padding: 12px 30px;
    }
    .btn-outline-light:hover {
      background: white;
      color: var(--primary);
    }
    /* Hero */
    .hero {
      min-height: 100vh;
      display: flex;
      align-items: center;
      background: linear-gradient(135deg, #F8FAFC 0%, #E2E8F0 100%);
      padding-top: 72px;
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
    }
    .hero-text {
      flex: 1;
    }
    .hero-text h1 {
      font-size: 48px;
      margin-bottom: 24px;
      color: var(--primary);
    }
    .hero-text .subtitle {
      font-size: 18px;
      color: var(--text-muted);
      margin-bottom: 36px;
      line-height: 1.6;
    }
    .hero-buttons {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }
    .hero-image {
      flex: 1;
      position: relative;
    }
    .hero-image img {
      border-radius: 16px;
      box-shadow: var(--shadow-hover);
      width: 100%;
      object-fit: cover;
    }
    /* 优势卡片 2+1布局 */
    .advantages-grid {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 24px;
      margin-top: 48px;
    }
    .adv-card {
      background: var(--card-white);
      padding: 32px 24px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      flex: 1 1 280px;
      max-width: 380px;
      text-align: center;
      transition: var(--transition);
    }
    .adv-card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }
    .adv-icon {
      font-size: 48px;
      color: var(--accent);
      margin-bottom: 20px;
    }
    .adv-card h3 {
      font-size: 20px;
      margin-bottom: 12px;
    }
    .adv-card p {
      color: var(--text-muted);
    }
    .row-break {
      width: 100%;
      display: flex;
      justify-content: center;
    }
    /* 数据 */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4,1fr);
      gap: 40px;
      text-align: center;
    }
    .stat-number {
      font-size: 40px;
      font-weight: 700;
      color: var(--emphasis);
      line-height: 1;
    }
    .stat-label {
      color: var(--text-muted);
      margin-top: 8px;
    }
    /* 左右图文 */
    .alt-block {
      display: flex;
      align-items: center;
      gap: 80px;
      margin-bottom: 100px;
    }
    .alt-reverse {
      flex-direction: row-reverse;
    }
    .alt-text {
      flex: 1;
    }
    .alt-text h2 {
      margin-bottom: 20px;
    }
    .alt-text ul {
      list-style: none;
      margin: 20px 0;
    }
    .alt-text li {
      padding: 8px 0;
      color: var(--text-body);
      display: flex;
      align-items: center;
      gap: 10px;
    }
    .alt-text li i {
      color: var(--accent);
    }
    .alt-image {
      flex: 1;
    }
    .alt-image img {
      border-radius: 12px;
      box-shadow: var(--shadow-card);
      width: 100%;
    }
    .learn-more {
      color: var(--accent);
      font-weight: 600;
      display: inline-flex;
      align-items: center; gap: 6px;
    }
    /* 案例卡片 */
    .case-grid {
      display: flex;
      gap: 24px;
      margin-top: 40px;
      flex-wrap: wrap;
    }
    .case-card {
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      flex: 1 1 300px;
      box-shadow: var(--shadow-card);
      transition: var(--transition);
    }
    .case-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-hover);
    }
    .case-img {
      position: relative;
      overflow: hidden;
    }
    .case-img img {
      transition: transform 0.3s;
      width: 100%; aspect-ratio: 16/9; object-fit: cover;
    }
    .case-card:hover .case-img img {
      transform: scale(1.05);
    }
    .badge {
      position: absolute;
      top: 16px; left: 16px;
      background: rgba(0,229,255,0.2);
      color: var(--accent);
      padding: 4px 12px;
      border-radius: 20px;
      font-weight: 600;
    }
    .case-info {
      padding: 20px;
    }
    /* 流程 */
    .steps {
      display: flex;
      justify-content: space-between;
      margin-top: 40px;
      position: relative;
    }
    .step-item {
      text-align: center;
      flex: 1;
      position: relative;
    }
    .step-circle {
      width: 44px; height: 44px;
      background: var(--primary);
      color: white;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      margin: 0 auto 20px;
      font-weight: 700;
    }
    .step-line {
      position: absolute;
      top: 22px; left: 50%; width: 100%; height: 2px;
      background: dashed #CBD5E1;
      z-index: -1;
    }
    /* FAQ */
    .faq-item {
      background: white;
      border-bottom: 1px solid var(--border-light);
      margin-bottom: 8px;
    }
    .faq-question {
      padding: 20px;
      font-weight: 500;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
      background: white;
      font-size: 18px;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: #F1F5F9;
      padding: 0 20px;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 20px;
    }
    .dark-section {
      background: var(--primary);
      color: white;
      text-align: center;
    }
    .footer {
      background: var(--primary);
      color: #CBD5E1;
      padding: 60px 0 20px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: repeat(4,1fr);
      gap: 40px;
    }
    .footer a:hover { color: var(--accent); }
    @media (max-width: 1024px) {
      h2 { font-size: 30px; }
      .hero-text h1 { font-size: 40px; }
    }
    @media (max-width: 768px) {
      .nav-menu { display: none; }
      .hamburger { display: flex; }
      .hero-grid { flex-direction: column; }
      .stats-grid { grid-template-columns: repeat(2,1fr); }
      .footer-grid { grid-template-columns: repeat(2,1fr); }
      .alt-block, .alt-reverse { flex-direction: column; }
    }
    @media (max-width: 640px) {
      .section { padding: 60px 0; }
      h2 { font-size: 28px; }
      .hero-text h1 { font-size: 32px; }
    }