/* roulang page: index */
/* ----- CSS 自定义属性 (设计变量) ----- */
    :root {
      --primary: #4E6EF2;
      --primary-hover: #3B5CD9;
      --primary-active: #2E4ABF;
      --primary-light: rgba(78,110,242,0.05);
      --primary-glow: rgba(78,110,242,0.3);
      
      --green: #00B578;
      --orange: #FF9F0A;
      --red: #FA5151;
      
      --text-primary: #1F2329;
      --text-secondary: #86909C;
      --bg-page: #F5F6FA;
      --card-bg: #FFFFFF;
      --border-light: #E5E8EF;
      
      --shadow-card: 0 1px 3px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
      --shadow-card-hover: 0 4px 12px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.04);
      --shadow-nav: 0 1px 2px rgba(0,0,0,0.05);
      
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-capsule: 24px;
      
      --font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      
      --container-max: 1200px;
      --section-padding: 80px;
      --card-gap: 24px;
      --page-margin: 24px;
      
      --nav-height: 64px;
      --nav-height-mobile: 56px;
    }
    
    /* ----- 基础重置 ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    
    html {
      scroll-behavior: smooth;
      -webkit-text-size-adjust: 100%;
    }
    
    body {
      font-family: var(--font-family);
      font-size: 16px;
      line-height: 1.6;
      color: var(--text-primary);
      background-color: var(--bg-page);
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }
    
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    
    a {
      text-decoration: none;
      color: inherit;
      transition: color 150ms ease;
    }
    
    button {
      font-family: inherit;
      cursor: pointer;
      border: none;
      background: none;
    }
    
    ul, ol {
      list-style: none;
    }
    
    /* ----- 容器 ----- */
    .container {
      width: 100%;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 var(--page-margin);
    }
    
    /* ----- 导航 ----- */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: #FFFFFF;
      z-index: 1000;
      transition: box-shadow 200ms ease;
      display: flex;
      align-items: center;
    }
    
    .site-header.scrolled {
      box-shadow: var(--shadow-nav);
    }
    
    .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: -0.3px;
    }
    
    .nav-menu {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    
    .nav-link {
      font-size: 16px;
      font-weight: 500;
      color: var(--text-primary);
      padding: 8px 0;
      transition: color 150ms;
      position: relative;
    }
    
    .nav-link:hover,
    .nav-link:focus-visible {
      color: var(--primary);
    }
    
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 10px 24px;
      font-size: 16px;
      font-weight: 500;
      border-radius: var(--radius-btn);
      transition: all 150ms ease;
      white-space: nowrap;
    }
    
    .btn-primary {
      background-color: var(--primary);
      color: #FFFFFF;
      box-shadow: 0 1px 2px rgba(0,0,0,0.05);
    }
    
    .btn-primary:hover {
      background-color: var(--primary-hover);
      box-shadow: 0 2px 6px rgba(0,0,0,0.1);
    }
    
    .btn-primary:active {
      background-color: var(--primary-active);
      box-shadow: inset 0 1px 3px rgba(0,0,0,0.1);
    }
    
    .btn-primary:focus-visible {
      outline: 2px solid var(--primary);
      outline-offset: 2px;
      box-shadow: 0 0 0 4px var(--primary-glow);
    }
    
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
    }
    
    .btn-outline:hover {
      background: var(--primary-light);
    }
    
    .btn-outline:active {
      background: rgba(78,110,242,0.1);
    }
    
    .btn-white {
      background: #FFFFFF;
      color: var(--primary);
      font-weight: 600;
    }
    
    .btn-white:hover {
      background: #F0F2FF;
    }
    
    .btn-ghost {
      background: transparent;
      border: 1.5px solid rgba(255,255,255,0.8);
      color: #FFFFFF;
    }
    
    .btn-ghost:hover {
      background: rgba(255,255,255,0.1);
    }
    
    /* 汉堡菜单 */
    .hamburger {
      display: none;
      flex-direction: column;
      justify-content: space-between;
      width: 24px;
      height: 18px;
      background: transparent;
      border: none;
      padding: 0;
    }
    
    .hamburger span {
      display: block;
      width: 100%;
      height: 2px;
      background: var(--text-primary);
      border-radius: 2px;
      transition: all 200ms;
    }
    
    /* 移动端菜单 */
    @media (max-width: 767px) {
      .nav-menu {
        position: fixed;
        top: var(--nav-height-mobile);
        left: 0;
        width: 100%;
        background: #FFFFFF;
        flex-direction: column;
        align-items: flex-start;
        padding: 24px var(--page-margin);
        gap: 20px;
        box-shadow: var(--shadow-nav);
        transform: translateY(-110%);
        opacity: 0;
        transition: transform 250ms ease, opacity 200ms ease;
        pointer-events: none;
        z-index: 999;
      }
      
      .nav-menu.active {
        transform: translateY(0);
        opacity: 1;
        pointer-events: auto;
      }
      
      .hamburger {
        display: flex;
      }
      
      .site-header {
        height: var(--nav-height-mobile);
      }
    }
    
    /* ----- 首屏 Hero ----- */
    .hero {
      padding: calc(var(--nav-height) + 40px) 0 60px;
      background: #FFFFFF;
    }
    
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }
    
    .hero-content h1 {
      font-size: 48px;
      font-weight: 700;
      line-height: 1.2;
      color: var(--text-primary);
      margin-bottom: 16px;
    }
    
    .hero-content .subtitle {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 32px;
      max-width: 480px;
    }
    
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    
    .hero-image {
      width: 100%;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-card);
    }
    
    .hero-image img {
      width: 100%;
      aspect-ratio: 4 / 3;
      object-fit: cover;
      display: block;
    }
    
    @media (max-width: 767px) {
      .hero-grid {
        grid-template-columns: 1fr;
        gap: 32px;
      }
      .hero-content h1 {
        font-size: 32px;
      }
      .hero-content .subtitle {
        font-size: 16px;
      }
      .hero-image img {
        aspect-ratio: 16 / 9;
      }
    }
    
    /* ----- 通用区块 ----- */
    .section {
      padding: var(--section-padding) 0;
    }
    
    .section-title {
      font-size: 32px;
      font-weight: 600;
      line-height: 1.3;
      color: var(--text-primary);
      margin-bottom: 12px;
      text-align: center;
    }
    
    .section-sub {
      font-size: 16px;
      color: var(--text-secondary);
      text-align: center;
      margin-bottom: 48px;
      max-width: 600px;
      margin-left: auto;
      margin-right: auto;
    }
    
    /* ----- 核心优势 (数据徽章) ----- */
    .advantages-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: var(--card-gap);
    }
    
    .stat-card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      padding: 32px 24px;
      text-align: center;
      box-shadow: var(--shadow-card);
      transition: box-shadow 200ms, transform 200ms;
    }
    
    .stat-card:hover {
      box-shadow: var(--shadow-card-hover);
      transform: translateY(-4px);
    }
    
    .stat-number {
      font-size: 56px;
      font-weight: 700;
      line-height: 1.1;
      color: var(--primary);
      margin-bottom: 8px;
    }
    
    .stat-label {
      font-size: 14px;
      color: var(--text-secondary);
    }
    
    /* ----- 服务卡片 ----- */
    .services-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: var(--card-gap);
    }
    
    .service-card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      padding: 32px;
      box-shadow: var(--shadow-card);
      transition: box-shadow 200ms, transform 200ms;
    }
    
    .service-card:hover {
      box-shadow: var(--shadow-card-hover);
      transform: translateY(-4px);
    }
    
    .service-icon {
      width: 48px;
      height: 48px;
      margin-bottom: 20px;
      color: var(--primary);
      display: flex;
      align-items: center;
      justify-content: center;
    }
    
    .service-icon svg {
      width: 100%;
      height: 100%;
      stroke-width: 1.5;
    }
    
    .service-card h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 8px;
      color: var(--text-primary);
    }
    
    .service-card p {
      font-size: 14px;
      color: var(--text-secondary);
      line-height: 1.5;
    }
    
    /* ----- 数据/案例展示 ----- */
    .data-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }
    
    .data-image img {
      width: 100%;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
    }
    
    .data-stats {
      display: flex;
      flex-direction: column;
      gap: 24px;
    }
    
    .data-item {
      display: flex;
      align-items: center;
      gap: 16px;
    }
    
    .data-icon {
      width: 40px;
      height: 40px;
      color: var(--primary);
      flex-shrink: 0;
    }
    
    .data-text strong {
      font-size: 40px;
      font-weight: 700;
      color: var(--primary);
      display: block;
      line-height: 1.1;
    }
    
    .data-text span {
      font-size: 14px;
      color: var(--text-secondary);
    }
    
    /* ----- FAQ 手风琴 ----- */
    .faq-list {
      max-width: 720px;
      margin: 0 auto;
    }
    
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    
    .faq-question {
      width: 100%;
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 16px 0;
      font-size: 18px;
      font-weight: 600;
      color: var(--text-primary);
      background: transparent;
      border: none;
      text-align: left;
      cursor: pointer;
    }
    
    .faq-icon {
      width: 20px;
      height: 20px;
      transition: transform 200ms ease;
    }
    
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 200ms ease-out, padding 200ms;
      padding: 0 0;
    }
    
    .faq-item.active .faq-answer {
      max-height: 300px;
      padding: 0 0 16px;
    }
    
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }
    
    .faq-answer p {
      font-size: 16px;
      color: var(--text-secondary);
      line-height: 1.6;
    }
    
    /* ----- 页脚 CTA ----- */
    .cta-section {
      background: var(--primary);
      padding: 60px 0;
      text-align: center;
    }
    
    .cta-title {
      font-size: 36px;
      font-weight: 700;
      color: #FFFFFF;
      margin-bottom: 12px;
    }
    
    .cta-sub {
      font-size: 16px;
      color: rgba(255,255,255,0.8);
      margin-bottom: 32px;
    }
    
    .cta-buttons {
      display: flex;
      justify-content: center;
      gap: 16px;
      flex-wrap: wrap;
    }
    
    /* 页脚信息 */
    .footer-bar {
      background: #1F2329;
      padding: 32px 0;
      color: #FFFFFF;
    }
    
    .footer-content {
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap;
      gap: 16px;
    }
    
    .footer-logo {
      font-size: 20px;
      font-weight: 700;
      color: #FFFFFF;
    }
    
    .footer-copy {
      font-size: 14px;
      color: rgba(255,255,255,0.7);
    }
    
    .footer-contact {
      font-size: 14px;
      color: rgba(255,255,255,0.8);
    }
    
    @media (max-width: 767px) {
      .advantages-grid,
      .services-grid {
        grid-template-columns: 1fr;
      }
      
      .data-grid {
        grid-template-columns: 1fr;
      }
      
      .section-title {
        font-size: 28px;
      }
      
      .cta-title {
        font-size: 28px;
      }
      
      .footer-content {
        flex-direction: column;
        text-align: center;
      }
      
      .stat-number {
        font-size: 40px;
      }
      
      .data-text strong {
        font-size: 32px;
      }
    }
    
    @media (min-width: 768px) and (max-width: 1024px) {
      .services-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }