/* roulang page: index */
:root {
      --primary-deep: #0B1A2E;
      --accent-cyan: #00C2BA;
      --accent-cyan-hover: #00A89E;
      --bg-light: #F7F9FC;
      --bg-white: #FFFFFF;
      --text-main: #1A2332;
      --text-secondary: #5A6876;
      --text-muted: #8D9AA8;
      --border-subtle: #E5E9F0;
      --shadow-card: 0 4px 20px rgba(0,0,0,0.04), 0 1px 3px rgba(0,0,0,0.04);
      --shadow-card-hover: 0 12px 32px rgba(0,0,0,0.08);
      --shadow-button: 0 2px 8px rgba(0,194,186,0.3);
      --radius-card: 12px;
      --radius-button: 8px;
      --radius-input: 8px;
      --transition-smooth: 0.25s ease;
      --max-width: 1200px;
      --nav-height: 68px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', 'Inter', system-ui, -apple-system, sans-serif;
      background-color: var(--bg-white);
      color: var(--text-main);
      line-height: 1.7;
      font-size: 16px;
      scroll-behavior: smooth;
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
      object-fit: cover;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s ease;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: none;
      transition: all var(--transition-smooth);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font-weight: 600;
      border-radius: var(--radius-button);
    }
    .section {
      padding: 100px 0;
    }
    h1, h2, h3, h4 {
      font-weight: 700;
      line-height: 1.3;
    }
    h1 {
      font-size: 48px;
      color: var(--primary-deep);
    }
    h2 {
      font-size: 36px;
      color: var(--primary-deep);
      margin-bottom: 16px;
    }
    h3 {
      font-size: 22px;
      color: var(--text-main);
    }
    h4 {
      font-size: 18px;
      color: var(--text-main);
    }
    .text-accent {
      color: var(--text-secondary);
      font-weight: 400;
    }
    .text-muted {
      color: var(--text-muted);
      font-size: 14px;
    }
    /* 导航 */
    .main-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(8px);
      z-index: 1000;
      box-shadow: 0 1px 0 var(--border-subtle);
      display: flex;
      align-items: center;
      transition: background 0.3s, box-shadow 0.3s;
    }
    .main-header.scrolled {
      background: #fff;
      box-shadow: 0 2px 12px rgba(0,0,0,0.05);
    }
    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo {
      font-size: 24px;
      font-weight: 700;
      color: var(--primary-deep);
      letter-spacing: 1px;
    }
    .logo span {
      color: var(--accent-cyan);
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
      list-style: none;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-main);
      font-size: 15px;
      transition: color 0.2s;
    }
    .nav-links a:hover {
      color: var(--accent-cyan);
    }
    .btn-nav {
      background: var(--accent-cyan);
      color: #fff;
      padding: 8px 20px;
      border-radius: 30px;
      font-size: 14px;
      box-shadow: var(--shadow-button);
    }
    .btn-nav:hover {
      background: var(--accent-cyan-hover);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
    }
    .hamburger div {
      width: 24px;
      height: 2px;
      background: var(--primary-deep);
      transition: 0.2s;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: var(--nav-height);
      left: 0;
      width: 100%;
      background: #fff;
      flex-direction: column;
      padding: 16px 0;
      box-shadow: 0 10px 20px rgba(0,0,0,0.05);
      z-index: 999;
    }
    .mobile-menu a {
      padding: 12px 24px;
      font-weight: 500;
      border-bottom: 1px solid var(--border-subtle);
    }
    /* Hero */
    .hero-section {
      padding-top: calc(var(--nav-height) + 60px);
      padding-bottom: 80px;
      background: var(--bg-light);
      background-image: radial-gradient(circle at 20% 30%, rgba(0,194,186,0.03) 0%, transparent 40%);
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
      flex-wrap: wrap;
    }
    .hero-left {
      flex: 1 1 500px;
    }
    .hero-right {
      flex: 1 1 450px;
      background: #E5E9F0;
      border-radius: var(--radius-card);
      overflow: hidden;
      height: 380px;
      box-shadow: var(--shadow-card);
    }
    .hero-right img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }
    .hero-subtitle {
      font-size: 18px;
      color: var(--text-secondary);
      margin: 16px 0 24px;
    }
    .hero-stats {
      display: flex;
      gap: 40px;
      margin: 32px 0;
    }
    .stat-number {
      font-size: 32px;
      font-weight: 700;
      color: var(--accent-cyan);
    }
    .stat-label {
      color: var(--text-muted);
      font-size: 14px;
    }
    .btn-primary {
      background: var(--accent-cyan);
      color: #fff;
      padding: 12px 32px;
      font-size: 16px;
      box-shadow: var(--shadow-button);
    }
    .btn-primary:hover {
      background: var(--accent-cyan-hover);
      transform: translateY(-1px);
    }
    /* 核心优势 不对称 */
    .features-grid {
      display: grid;
      grid-template-columns: 1.5fr 1fr;
      gap: 24px;
    }
    .feature-card {
      background: #fff;
      border-radius: var(--radius-card);
      padding: 32px;
      box-shadow: var(--shadow-card);
      transition: all 0.3s;
    }
    .feature-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-card-hover);
    }
    .feature-large {
      display: flex;
      flex-direction: column;
      justify-content: center;
    }
    .feature-icon {
      font-size: 36px;
      color: var(--accent-cyan);
      margin-bottom: 20px;
    }
    /* 产品交替区块 */
    .product-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 100px;
      flex-wrap: wrap;
    }
    .product-text {
      flex: 1 1 400px;
    }
    .product-img {
      flex: 1 1 400px;
      background: #E5E9F0;
      border-radius: var(--radius-card);
      height: 320px;
      overflow: hidden;
      border: 2px solid var(--accent-cyan);
      border-opacity: 0.2;
    }
    .product-img img {
      width: 100%;
      height: 100%;
    }
    .btn-outline {
      border: 2px solid var(--accent-cyan);
      color: var(--primary-deep);
      padding: 10px 28px;
      background: transparent;
    }
    .btn-outline:hover {
      background: var(--accent-cyan);
      color: #fff;
    }
    /* 场景卡片横向滑动 */
    .scenarios-wrap {
      display: flex;
      gap: 24px;
      overflow-x: auto;
      padding-bottom: 16px;
      scroll-snap-type: x mandatory;
    }
    .scenario-card {
      flex: 0 0 280px;
      background: #fff;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      overflow: hidden;
      scroll-snap-align: start;
      transition: 0.3s;
    }
    .scenario-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-card-hover);
    }
    .scenario-img {
      height: 160px;
      background: #E5E9F0;
    }
    .scenario-img img {
      width: 100%;
      height: 100%;
    }
    .scenario-info {
      padding: 20px;
    }
    /* 数据看板 */
    .stats-board {
      display: flex;
      justify-content: space-around;
      background: #EEF2F7;
      border-radius: var(--radius-card);
      padding: 48px 24px;
      flex-wrap: wrap;
    }
    .big-number {
      font-size: 44px;
      font-weight: 700;
      color: var(--accent-cyan);
    }
    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-subtle);
      padding: 20px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      font-weight: 700;
      cursor: pointer;
      background: transparent;
      border: none;
      width: 100%;
      text-align: left;
      font-size: 18px;
      color: var(--text-main);
      padding: 10px 0;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-secondary);
    }
    .faq-item.active .faq-answer {
      max-height: 150px;
      margin-top: 10px;
    }
    /* CTA 尾屏 */
    .cta-dark {
      background: var(--primary-deep);
      color: #fff;
      text-align: center;
      border-radius: 0;
    }
    .cta-dark h2 {
      color: #fff;
    }
    /* 页脚 */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }
    .copyright {
      border-top: 1px solid var(--border-subtle);
      margin-top: 40px;
      padding-top: 24px;
      text-align: center;
      color: var(--text-muted);
      font-size: 14px;
    }
    @media (max-width: 992px) {
      .features-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }
    @media (max-width: 768px) {
      h1 { font-size: 36px; }
      h2 { font-size: 28px; }
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .hero-grid { flex-direction: column; }
      .product-row { flex-direction: column; }
      .product-img { height: 240px; }
      .section { padding: 70px 0; }
      .stats-board { gap: 24px; }
      .btn { padding: 12px 24px; }
    }
    @media (max-width: 520px) {
      .container { padding: 0 16px; }
      h1 { font-size: 32px; }
      .scenario-card { flex: 0 0 240px; }
    }