/* roulang page: index */
:root {
      --primary: #0A66C2;
      --primary-light: rgba(10, 102, 194, 0.08);
      --primary-soft: rgba(10, 102, 194, 0.15);
      --secondary-bg: #F5F7FA;
      --card-bg: #FFFFFF;
      --text-main: #101010;
      --text-body: #4A4A4A;
      --text-muted: #8C8C8C;
      --accent: #FF5A1F;
      --border-light: #E5E7EB;
      --shadow-card: 0 2px 12px rgba(0,0,0,0.06);
      --shadow-hover: 0 8px 24px rgba(0,0,0,0.10);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-img: 8px;
      --max-width: 1200px;
      --nav-height: 64px;
      --mobile-nav-height: 56px;
      --section-padding: 80px;
      --section-mobile-padding: 48px;
      --font-stack: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
      scroll-padding-top: var(--nav-height);
    }
    body {
      font-family: var(--font-stack);
      background-color: var(--secondary-bg);
      color: var(--text-body);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s ease;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      border: none;
      background: none;
      transition: all 0.2s ease;
      font-weight: 600;
      border-radius: var(--radius-btn);
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }
    /* 导航桌面 */
    .desktop-nav {
      display: block;
    }
    .mobile-nav {
      display: none;
    }
    header {
      background: rgba(255,255,255,0.85);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      height: var(--nav-height);
      display: flex;
      align-items: center;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 999;
      border-bottom: 1px solid var(--border-light);
      transition: background 0.2s;
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo {
      font-size: 20px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: -0.2px;
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-links a {
      font-size: 16px;
      font-weight: 500;
      color: var(--text-main);
      padding: 8px 0;
      position: relative;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width 0.2s ease;
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }
    /* 移动端底部导航 */
    .bottom-mobile-nav {
      display: none;
      position: fixed;
      bottom: 0;
      left: 0;
      width: 100%;
      height: var(--mobile-nav-height);
      background: #ffffff;
      box-shadow: 0 -2px 12px rgba(0,0,0,0.04);
      z-index: 998;
      justify-content: space-around;
      align-items: center;
      border-top: 1px solid #E5E7EB;
    }
    .bottom-mobile-nav .nav-item {
      display: flex;
      flex-direction: column;
      align-items: center;
      font-size: 12px;
      color: #8C8C8C;
      font-weight: 500;
      transition: color 0.2s;
      gap: 4px;
    }
    .bottom-mobile-nav .nav-item i {
      font-size: 20px;
    }
    .bottom-mobile-nav .nav-item.active {
      color: var(--primary);
    }
    /* Hero */
    .hero {
      padding: calc(var(--nav-height) + 60px) 0 var(--section-padding);
      background: linear-gradient(180deg, #F5F7FA 0%, #EEF2F6 100%);
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 48px;
    }
    .hero-left {
      flex: 1 1 50%;
    }
    .hero-right {
      flex: 1 1 50%;
      display: flex;
      justify-content: center;
      position: relative;
      height: 400px;
    }
    .hero h1 {
      font-size: 44px;
      font-weight: 700;
      line-height: 1.2;
      color: var(--text-main);
      margin-bottom: 20px;
    }
    .hero-sub {
      font-size: 18px;
      color: var(--text-body);
      margin-bottom: 32px;
      max-width: 480px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--accent);
      color: #fff;
      padding: 12px 28px;
      font-size: 16px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      box-shadow: 0 4px 12px rgba(255,90,31,0.25);
    }
    .btn-primary:hover {
      background: #e04e1a;
      transform: translateY(-1px);
    }
    .btn-outline {
      border: 2px solid var(--primary);
      color: var(--primary);
      background: transparent;
      padding: 12px 28px;
      font-size: 16px;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-outline:hover {
      background: var(--primary-light);
    }
    .hero-cards {
      position: relative;
      width: 100%;
      height: 100%;
    }
    .hero-card {
      position: absolute;
      width: 260px;
      height: 180px;
      background: #fff;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      overflow: hidden;
      object-fit: cover;
      border: 1px solid rgba(0,0,0,0.03);
    }
    .hero-card img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }
    .hero-card:nth-child(1) {
      top: 20px;
      left: 10px;
      transform: rotate(-3deg);
      z-index: 2;
    }
    .hero-card:nth-child(2) {
      top: 100px;
      left: 100px;
      transform: rotate(0deg);
      z-index: 3;
    }
    .hero-card:nth-child(3) {
      top: 170px;
      left: 30px;
      transform: rotate(4deg);
      z-index: 1;
    }
    /* 通用区块 */
    section {
      padding: var(--section-padding) 0;
    }
    .bg-white {
      background-color: #fff;
    }
    .bg-light {
      background-color: var(--secondary-bg);
    }
    .section-title {
      font-size: 32px;
      font-weight: 600;
      line-height: 1.3;
      color: var(--text-main);
      margin-bottom: 16px;
    }
    .section-sub {
      font-size: 16px;
      color: var(--text-muted);
      margin-bottom: 48px;
      max-width: 680px;
    }
    /* 核心功能 - 列表卡片 */
    .feature-list-card {
      background: #fff;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      padding: 28px;
    }
    .feature-item {
      display: flex;
      align-items: center;
      gap: 24px;
      padding: 24px 0;
      border-bottom: 1px solid #f0f0f0;
    }
    .feature-item:last-child {
      border-bottom: none;
    }
    .feature-icon {
      width: 56px;
      height: 56px;
      background: var(--primary-light);
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 28px;
      color: var(--primary);
      flex-shrink: 0;
    }
    .feature-text h3 {
      font-size: 20px;
      font-weight: 600;
      color: var(--text-main);
      margin-bottom: 6px;
    }
    .feature-text p {
      color: var(--text-body);
      font-size: 15px;
    }
    /* 使用场景 2x2 */
    .scene-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 24px;
    }
    .scene-card {
      background: #fff;
      border-radius: var(--radius-card);
      padding: 20px;
      display: flex;
      gap: 20px;
      align-items: center;
      box-shadow: var(--shadow-card);
      transition: all 0.2s ease;
    }
    .scene-card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-2px);
    }
    .scene-img {
      width: 100px;
      height: 100px;
      border-radius: var(--radius-img);
      object-fit: cover;
      flex-shrink: 0;
    }
    .scene-content h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 8px;
      color: var(--text-main);
    }
    /* 数据指标墙 */
    .stats-wall {
      display: flex;
      justify-content: center;
      flex-wrap: wrap;
      gap: 48px;
      text-align: center;
    }
    .stat-number {
      font-size: 44px;
      font-weight: 700;
      color: var(--accent);
      line-height: 1.2;
    }
    .stat-label {
      color: var(--text-body);
      font-size: 15px;
      margin-top: 8px;
    }
    /* FAQ 手风琴 */
    .faq-list {
      display: flex;
      flex-direction: column;
      gap: 0;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      width: 100%;
      background: #fff;
      padding: 20px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 18px;
      font-weight: 600;
      color: var(--text-main);
      border: none;
      cursor: pointer;
      text-align: left;
    }
    .faq-icon {
      font-size: 20px;
      color: var(--primary);
      transition: transform 0.3s ease;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s;
      background: #F9FAFB;
      padding: 0 0;
      color: var(--text-body);
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding: 16px 0;
    }
    .faq-item.open .faq-icon {
      transform: rotate(45deg);
    }
    /* 最终CTA */
    .cta-section {
      background: var(--primary);
      color: #fff;
      text-align: center;
      padding: 80px 0;
    }
    .cta-title {
      font-size: 32px;
      font-weight: 700;
      margin-bottom: 16px;
    }
    .btn-white {
      background: #fff;
      color: var(--primary);
      padding: 14px 40px;
      font-weight: 700;
      font-size: 16px;
      margin-top: 24px;
    }
    .btn-white:hover {
      background: #f0f4fa;
    }
    /* 页脚 */
    footer {
      background: #1A1A1A;
      color: #B0B0B0;
      padding: 48px 0 24px;
      font-size: 15px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
    }
    .footer-logo {
      font-size: 22px;
      font-weight: 700;
      color: #fff;
      margin-bottom: 12px;
    }
    .footer-desc {
      color: #B0B0B0;
    }
    footer h4 {
      color: #fff;
      margin-bottom: 16px;
      font-size: 16px;
    }
    footer a {
      color: #B0B0B0;
      display: block;
      margin-bottom: 10px;
    }
    footer a:hover {
      color: #fff;
    }
    .copyright {
      border-top: 1px solid #333;
      margin-top: 40px;
      padding-top: 20px;
      text-align: center;
      color: #8C8C8C;
    }
    /* 响应式 */
    @media (max-width: 1024px) {
      .hero h1 {
        font-size: 36px;
      }
      .hero-grid {
        flex-direction: column;
      }
      .hero-right {
        height: 300px;
        margin-top: 32px;
      }
      .hero-card {
        width: 200px;
        height: 140px;
      }
    }
    @media (max-width: 768px) {
      .desktop-nav {
        display: none;
      }
      header {
        display: none;
      }
      .bottom-mobile-nav {
        display: flex;
      }
      .hero {
        padding: 48px 0 48px;
      }
      .hero h1 {
        font-size: 28px;
      }
      .section-title {
        font-size: 26px;
      }
      section {
        padding: var(--section-mobile-padding) 0;
      }
      .scene-grid {
        grid-template-columns: 1fr;
      }
      .stats-wall {
        gap: 24px;
      }
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
      .hero-card {
        width: 160px;
        height: 120px;
      }
      .feature-item {
        flex-direction: column;
        align-items: flex-start;
      }
    }
    @media (max-width: 520px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
      .hero-buttons {
        flex-direction: column;
        align-items: flex-start;
      }
    }