/* roulang page: index */
:root {
      --primary: #0A0E27;
      --accent: #00F0FF;
      --emphasis: #FF3D00;
      --bg-light: #FAFAFA;
      --card-bg: #FFFFFF;
      --text-dark: #1A1A1A;
      --text-body: #4A4A4A;
      --text-muted: #8A8A8A;
      --text-on-dark: #FFFFFF;
      --text-on-dark-muted: #B0B8C8;
      --border-light: #E5E7EB;
      --border-dark: rgba(255,255,255,0.08);
      --shadow-card: 0 4px 20px rgba(0,0,0,0.04), 0 1px 3px rgba(0,0,0,0.03);
      --shadow-card-hover: 0 12px 32px rgba(0,0,0,0.08);
      --radius-card: 16px;
      --radius-btn: 8px;
      --radius-pill: 24px;
      --font-inter: 'Inter', 'SF Pro Display', system-ui, -apple-system, sans-serif;
      --font-system: 'PingFang SC', 'Microsoft YaHei', 'Source Han Sans CN', 'Noto Sans CJK SC', system-ui, -apple-system, sans-serif;
      --container-max: 1280px;
      --section-gap-desktop: 120px;
      --section-gap-tablet: 80px;
      --section-gap-mobile: 60px;
      --nav-height-desktop: 72px;
      --nav-height-mobile: 56px;
    }

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

    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }

    body {
      font-family: var(--font-system);
      background-color: var(--bg-light);
      color: var(--text-body);
      line-height: 1.65;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
      overflow-x: hidden;
    }

    .english-number {
      font-family: var(--font-inter);
      letter-spacing: -0.02em;
    }

    img {
      max-width: 100%;
      height: auto;
      display: block;
    }

    a {
      text-decoration: none;
      color: inherit;
      transition: color 200ms ease;
    }

    button {
      font-family: inherit;
      cursor: pointer;
      border: none;
      background: none;
    }

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

    @media (max-width: 640px) {
      .container {
        padding: 0 16px;
      }
    }

    /* 导航 */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      height: var(--nav-height-desktop);
      transition: background 300ms ease, box-shadow 300ms ease, backdrop-filter 300ms ease;
      background: transparent;
    }

    .site-header.scrolled {
      background: rgba(255,255,255,0.85);
      backdrop-filter: blur(12px);
      box-shadow: 0 10px 25px -10px rgba(0,0,0,0.05);
      border-bottom: 1px solid rgba(0,0,0,0.02);
    }

    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 100%;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 20px;
    }

    .logo {
      font-family: var(--font-inter);
      font-size: 22px;
      font-weight: 800;
      color: #fff;
      letter-spacing: -0.5px;
      transition: color 300ms;
    }
    .scrolled .logo {
      color: var(--primary);
    }

    .logo span {
      color: var(--accent);
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
      list-style: none;
    }

    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: rgba(255,255,255,0.85);
      padding: 6px 0;
      position: relative;
      transition: color 200ms;
    }

    .scrolled .nav-links a {
      color: var(--text-body);
    }

    .nav-links a:hover,
    .nav-links a.active {
      color: #fff;
    }
    .scrolled .nav-links a:hover,
    .scrolled .nav-links a.active {
      color: var(--primary);
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 50%;
      transform: translateX(-50%);
      width: 0;
      height: 2px;
      background: var(--accent);
      transition: width 200ms;
      border-radius: 2px;
    }

    .nav-links a.active::after,
    .nav-links a:hover::after {
      width: 20px;
    }

    .btn-nav {
      background: var(--emphasis);
      color: white;
      font-weight: 600;
      font-size: 14px;
      padding: 10px 22px;
      border-radius: var(--radius-btn);
      transition: background 200ms, transform 200ms;
      letter-spacing: 0.5px;
      border: none;
    }
    .btn-nav:hover {
      background: #D93200;
      transform: scale(1.03);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: transparent;
      border: none;
      width: 28px;
      height: 20px;
      justify-content: center;
      align-items: center;
      z-index: 1001;
    }
    .hamburger span {
      display: block;
      width: 24px;
      height: 2px;
      background: #fff;
      transition: 300ms;
      border-radius: 2px;
    }
    .scrolled .hamburger span {
      background: var(--primary);
    }

    @media (max-width: 1024px) {
      .nav-links {
        gap: 24px;
      }
    }

    @media (max-width: 768px) {
      .hamburger {
        display: flex;
      }
      .nav-links {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 320px;
        height: 100vh;
        background: #fff;
        flex-direction: column;
        padding: 100px 40px 40px;
        gap: 28px;
        box-shadow: -10px 0 30px rgba(0,0,0,0.1);
        transition: right 350ms ease;
        align-items: flex-start;
      }
      .nav-links.active {
        right: 0;
      }
      .nav-links a {
        color: var(--text-dark) !important;
        font-size: 18px;
      }
      .btn-nav {
        width: 100%;
        text-align: center;
      }
      .site-header {
        background: rgba(10,14,39,0.9);
        backdrop-filter: blur(8px);
      }
      .scrolled .site-header {
        background: rgba(255,255,255,0.95);
      }
    }

    /* 板块通用 */
    section {
      padding: var(--section-gap-desktop) 0;
    }
    @media (max-width: 1024px) {
      section {
        padding: var(--section-gap-tablet) 0;
      }
    }
    @media (max-width: 640px) {
      section {
        padding: var(--section-gap-mobile) 0;
      }
    }

    .section-title {
      font-size: 40px;
      font-weight: 700;
      line-height: 1.25;
      color: var(--text-dark);
      margin-bottom: 16px;
    }
    .section-desc {
      font-size: 18px;
      line-height: 1.75;
      color: var(--text-body);
      max-width: 680px;
    }

    /* Hero */
    .hero {
      background: var(--primary);
      position: relative;
      min-height: 100vh;
      display: flex;
      align-items: center;
      padding-top: var(--nav-height-desktop);
      overflow: hidden;
    }
    .hero::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: radial-gradient(circle at 20% 30%, rgba(0,240,255,0.08) 0%, transparent 50%);
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
    }
    .hero-text {
      flex: 1;
      position: relative;
      z-index: 2;
    }
    .hero-badge {
      display: inline-block;
      font-size: 12px;
      font-weight: 600;
      letter-spacing: 2px;
      color: var(--accent);
      text-transform: uppercase;
      margin-bottom: 24px;
    }
    .hero h1 {
      font-size: 56px;
      font-weight: 900;
      line-height: 1.15;
      color: white;
      margin-bottom: 24px;
    }
    .hero-sub {
      font-size: 18px;
      color: var(--text-on-dark-muted);
      margin-bottom: 40px;
      max-width: 500px;
    }
    .hero-actions {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
      margin-bottom: 48px;
    }
    .btn-primary {
      background: var(--emphasis);
      color: white;
      font-weight: 600;
      font-size: 16px;
      padding: 14px 36px;
      border-radius: var(--radius-btn);
      transition: background 200ms, transform 200ms, box-shadow 200ms;
      letter-spacing: 0.5px;
      border: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
    }
    .btn-primary:hover {
      background: #D93200;
      transform: scale(1.03);
      box-shadow: 0 8px 18px rgba(255,61,0,0.3);
    }
    .btn-ghost {
      border: 1.5px solid white;
      color: white;
      background: transparent;
      padding: 14px 36px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
      transition: 200ms;
    }
    .btn-ghost:hover {
      background: white;
      color: var(--primary);
    }
    .trust-stats {
      display: flex;
      gap: 32px;
      color: var(--text-on-dark-muted);
      font-size: 14px;
      flex-wrap: wrap;
    }
    .hero-image {
      flex: 1;
      position: relative;
      z-index: 1;
    }
    .hero-image img {
      border-radius: 24px;
      box-shadow: 0 25px 50px -12px rgba(0,0,0,0.5);
      width: 100%;
    }
    @media (max-width: 1024px) {
      .hero-grid {
        flex-direction: column;
        text-align: center;
      }
      .hero h1 {
        font-size: 48px;
      }
      .hero-sub {
        max-width: 100%;
      }
      .hero-actions {
        justify-content: center;
      }
      .trust-stats {
        justify-content: center;
      }
    }
    @media (max-width: 640px) {
      .hero h1 {
        font-size: 36px;
      }
      .hero-sub {
        font-size: 16px;
      }
    }

    /* 优势区 */
    .advantages-grid {
      display: flex;
      gap: 60px;
      align-items: flex-start;
      margin-top: 40px;
    }
    .adv-left {
      flex: 1;
    }
    .adv-right {
      flex: 1;
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 32px;
    }
    .adv-card {
      background: var(--card-bg);
      padding: 32px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: 300ms;
    }
    .adv-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-card-hover);
    }
    .adv-number {
      font-size: 32px;
      font-weight: 700;
      color: var(--accent);
      font-family: var(--font-inter);
      margin-bottom: 12px;
    }
    .adv-card h3 {
      font-size: 20px;
      font-weight: 600;
      color: var(--text-dark);
      margin-bottom: 8px;
    }
    @media (max-width: 768px) {
      .advantages-grid {
        flex-direction: column;
      }
      .adv-right {
        grid-template-columns: 1fr;
      }
    }

    /* 功能图文 */
    .feature-group {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-top: 60px;
    }
    .feature-group.reverse {
      flex-direction: row-reverse;
    }
    .feature-img {
      flex: 1;
    }
    .feature-img img {
      border-radius: 16px;
      box-shadow: var(--shadow-card);
      width: 100%;
    }
    .feature-content {
      flex: 1;
    }
    .feature-list {
      list-style: none;
      margin: 20px 0;
    }
    .feature-list li {
      padding-left: 20px;
      position: relative;
      margin-bottom: 10px;
      color: var(--text-body);
    }
    .feature-list li::before {
      content: '';
      position: absolute;
      left: 0;
      top: 10px;
      width: 6px;
      height: 6px;
      background: var(--accent);
      border-radius: 50%;
    }
    @media (max-width: 768px) {
      .feature-group, .feature-group.reverse {
        flex-direction: column;
      }
    }

    /* 场景卡片 */
    .scene-cards {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 40px;
    }
    .scene-card {
      background: #f4f5f7;
      padding: 32px;
      border-radius: var(--radius-card);
      transition: 300ms;
    }
    .scene-card:hover {
      background: white;
      box-shadow: var(--shadow-card-hover);
    }
    @media (max-width: 768px) {
      .scene-cards {
        grid-template-columns: 1fr;
      }
    }

    /* 案例区 */
    .case-section {
      background: var(--primary);
      color: white;
    }
    .logo-wall {
      display: flex;
      flex-wrap: wrap;
      gap: 40px;
      justify-content: center;
      margin: 40px 0;
      opacity: 0.7;
    }
    .metrics {
      display: flex;
      justify-content: center;
      gap: 60px;
      margin: 40px 0;
      text-align: center;
    }
    .metric-number {
      font-size: 48px;
      font-weight: 800;
      color: var(--accent);
    }
    @media (max-width: 640px) {
      .metrics {
        flex-direction: column;
        gap: 30px;
      }
    }

    /* 价格 */
    .pricing-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 40px;
    }
    .price-card {
      background: white;
      padding: 32px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: 300ms;
      position: relative;
    }
    .price-card.featured {
      border: 2px solid var(--emphasis);
      transform: translateY(-8px);
    }
    @media (max-width: 768px) {
      .pricing-grid {
        grid-template-columns: 1fr;
      }
      .price-card.featured {
        transform: none;
      }
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 18px 0;
    }
    .faq-question {
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
    }

    /* CTA */
    .cta-section {
      background: var(--primary);
      text-align: center;
    }
    .footer {
      background: var(--primary);
      color: var(--text-on-dark-muted);
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }
    .fade-up {
      opacity: 0;
      transform: translateY(20px);
      transition: opacity 600ms ease, transform 600ms ease;
    }
    .fade-up.visible {
      opacity: 1;
      transform: translateY(0);
    }