/* roulang page: index */
/* ----- 设计变量与全局重置 ----- */
    :root {
      --primary: #4E6EF2;
      --primary-hover: #3A5CE4;
      --primary-shadow: rgba(78, 110, 242, 0.3);
      --success: #00B578;
      --warning: #FF9F0A;
      --danger: #FA5151;
      --bg-page: #F5F6FA;
      --bg-white: #FFFFFF;
      --bg-dark: #1F2329;
      --text-primary: #1F2329;
      --text-secondary: #86909C;
      --border-light: #E5E8EF;
      --fill-light: #F0F2F5;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 24px;
      --shadow-card: 0 2px 8px rgba(31, 35, 41, 0.04);
      --shadow-hover: 0 4px 16px rgba(31, 35, 41, 0.08);
      --shadow-nav: 0 1px 4px rgba(31, 35, 41, 0.06);
      --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --transition-fast: 200ms ease-out;
      --transition-smooth: 250ms cubic-bezier(0.25, 0.1, 0.25, 1);
      --container-max: 1200px;
      --header-height: 64px;
    }
    
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    
    html {
      scroll-behavior: smooth;
      scroll-padding-top: var(--header-height);
    }
    
    body {
      font-family: var(--font-stack);
      background-color: var(--bg-page);
      color: var(--text-primary);
      line-height: 1.6;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition-fast);
    }
    
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      outline: none;
      transition: all var(--transition-fast);
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-weight: 500;
    }
    
    /* 容器与栅格 */
    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
      width: 100%;
    }
    
    @media (max-width: 767px) {
      .container {
        padding: 0 16px;
      }
    }
    
    /* 导航系统 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--header-height);
      background: var(--bg-white);
      box-shadow: var(--shadow-nav);
      z-index: 1000;
      display: flex;
      align-items: center;
    }
    
    .header .container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 100%;
    }
    
    .logo {
      font-size: 22px;
      font-weight: 700;
      color: var(--text-primary);
      letter-spacing: -0.3px;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    
    .logo i {
      color: var(--primary);
      font-size: 26px;
    }
    
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
      list-style: none;
    }
    
    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-primary);
      position: relative;
      padding: 8px 0;
      transition: color var(--transition-fast);
    }
    
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
    }
    
    .nav-links a.active::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      height: 2px;
      background: var(--primary);
    }
    
    .header-cta {
      background: var(--primary);
      color: white;
      padding: 10px 20px;
      border-radius: var(--radius-btn);
      font-size: 14px;
      font-weight: 600;
      white-space: nowrap;
      box-shadow: 0 2px 6px rgba(78,110,242,0.2);
    }
    
    .header-cta:hover {
      background: var(--primary-hover);
      box-shadow: var(--primary-shadow) 0 4px 12px;
      transform: scale(1.02);
    }
    
    .hamburger {
      display: none;
      font-size: 24px;
      background: none;
      color: var(--text-primary);
      padding: 8px;
    }
    
    @media (max-width: 1024px) {
      .nav-links {
        gap: 24px;
      }
    }
    
    @media (max-width: 767px) {
      .hamburger {
        display: block;
        z-index: 1001;
      }
      .nav-links {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100vh;
        background: white;
        flex-direction: column;
        justify-content: center;
        align-items: flex-start;
        padding: 40px 32px;
        gap: 28px;
        transform: translateX(-100%);
        transition: transform 0.3s ease;
        z-index: 999;
      }
      .nav-links.open {
        transform: translateX(0);
      }
      .nav-links a {
        font-size: 18px;
      }
      .header-cta.desktop-only {
        display: none;
      }
      .mobile-cta {
        display: block;
        margin-top: 24px;
        width: 100%;
      }
    }
    
    @media (min-width: 768px) {
      .mobile-cta {
        display: none;
      }
    }
    
    /* 板块通用间距 */
    section {
      padding: 90px 0;
    }
    
    @media (max-width: 767px) {
      section {
        padding: 60px 0;
      }
    }
    
    /* Hero 首屏 */
    .hero {
      background: linear-gradient(180deg, #FFFFFF 0%, #F5F6FA 100%);
      padding-top: calc(var(--header-height) + 60px);
      padding-bottom: 80px;
      display: flex;
      align-items: center;
    }
    
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
      flex-wrap: wrap;
    }
    
    .hero-content {
      flex: 1 1 450px;
    }
    
    .hero h1 {
      font-size: 44px;
      font-weight: 700;
      color: var(--text-primary);
      line-height: 1.25;
      margin-bottom: 20px;
      letter-spacing: -0.5px;
    }
    
    .hero .subtitle {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 32px;
      max-width: 500px;
      line-height: 1.6;
    }
    
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-size: 16px;
      font-weight: 600;
      box-shadow: 0 4px 10px rgba(78,110,242,0.25);
    }
    
    .btn-primary:hover {
      background: var(--primary-hover);
      box-shadow: var(--primary-shadow) 0 6px 16px;
      transform: translateY(-1px);
    }
    
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--border-light);
      color: var(--text-primary);
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-size: 16px;
      font-weight: 500;
    }
    
    .btn-outline:hover {
      border-color: var(--primary);
      color: var(--primary);
    }
    
    .hero-image {
      flex: 1 1 400px;
      text-align: center;
    }
    
    .hero-image img {
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-hover);
      width: 100%;
      max-width: 550px;
      margin: 0 auto;
    }
    
    @media (max-width: 767px) {
      .hero h1 {
        font-size: 32px;
      }
      .hero .subtitle {
        font-size: 16px;
      }
      .hero-grid {
        gap: 40px;
        flex-direction: column;
      }
      .hero-buttons .btn {
        width: 100%;
        justify-content: center;
      }
    }
    
    /* 标题组件 */
    .section-title {
      text-align: center;
      margin-bottom: 56px;
    }
    
    .section-title h2 {
      font-size: 32px;
      font-weight: 700;
      color: var(--text-primary);
      margin-bottom: 12px;
    }
    
    .section-title p {
      color: var(--text-secondary);
      font-size: 16px;
      max-width: 600px;
      margin: 0 auto;
    }
    
    /* 卡片系统 */
    .card-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    
    .card {
      background: var(--bg-white);
      border-radius: var(--radius-card);
      padding: 32px 24px;
      box-shadow: var(--shadow-card);
      transition: all var(--transition-smooth);
      display: flex;
      flex-direction: column;
      align-items: flex-start;
    }
    
    .card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
    }
    
    .icon-box {
      width: 56px;
      height: 56px;
      background: var(--fill-light);
      border-radius: 12px;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 20px;
      color: var(--primary);
      font-size: 28px;
    }
    
    .card h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 10px;
    }
    
    .card p {
      color: var(--text-secondary);
      font-size: 15px;
      line-height: 1.6;
      margin-bottom: 16px;
      flex: 1;
    }
    
    .card-link {
      color: var(--primary);
      font-weight: 500;
      font-size: 14px;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }
    
    .card-link:hover {
      text-decoration: underline;
    }
    
    @media (max-width: 1024px) {
      .card-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    
    @media (max-width: 767px) {
      .card-grid {
        grid-template-columns: 1fr;
      }
    }
    
    /* 优势数据区 */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 32px;
      text-align: center;
    }
    
    .stat-item .stat-number {
      font-size: 44px;
      font-weight: 700;
      color: var(--primary);
      line-height: 1.2;
      margin-bottom: 8px;
    }
    
    .stat-item .stat-label {
      font-size: 15px;
      color: var(--text-secondary);
    }
    
    @media (max-width: 1024px) {
      .stats-grid {
        grid-template-columns: repeat(2, 1fr);
        gap: 40px;
      }
    }
    
    @media (max-width: 767px) {
      .stats-grid {
        grid-template-columns: 1fr 1fr;
        gap: 32px;
      }
      .stat-number {
        font-size: 36px;
      }
    }
    
    /* 案例卡片 */
    .case-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    
    .case-card {
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-card);
      transition: var(--transition-smooth);
    }
    
    .case-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-hover);
    }
    
    .case-img {
      height: 200px;
      overflow: hidden;
    }
    
    .case-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.3s ease;
    }
    
    .case-card:hover .case-img img {
      transform: scale(1.03);
    }
    
    .case-info {
      padding: 20px 20px 24px;
    }
    
    .case-info h3 {
      font-size: 18px;
      font-weight: 600;
      margin-bottom: 8px;
    }
    
    .case-info p {
      font-size: 14px;
      color: var(--text-secondary);
      margin-bottom: 12px;
    }
    
    .tag {
      background: rgba(78,110,242,0.1);
      color: var(--primary);
      padding: 4px 10px;
      border-radius: 4px;
      font-size: 12px;
      font-weight: 500;
      display: inline-block;
    }
    
    @media (max-width: 1024px) {
      .case-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    
    @media (max-width: 767px) {
      .case-grid {
        grid-template-columns: 1fr;
      }
    }
    
    /* FAQ 手风琴 */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    
    .faq-item {
      background: var(--bg-white);
      border-radius: 8px;
      margin-bottom: 12px;
      box-shadow: 0 1px 4px rgba(0,0,0,0.02);
      overflow: hidden;
    }
    
    .faq-question {
      width: 100%;
      background: transparent;
      padding: 18px 20px;
      font-size: 16px;
      font-weight: 500;
      display: flex;
      justify-content: space-between;
      align-items: center;
      color: var(--text-primary);
    }
    
    .faq-question i {
      transition: transform 0.25s ease;
      color: var(--text-secondary);
    }
    
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      padding: 0 20px;
      color: var(--text-secondary);
      font-size: 15px;
      line-height: 1.6;
      background: white;
    }
    
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 18px;
    }
    
    .faq-item.active .faq-question i {
      transform: rotate(45deg);
      color: var(--primary);
    }
    
    /* 最终 CTA */
    .cta-section {
      background: var(--bg-dark);
      color: white;
      text-align: center;
      padding: 100px 0;
    }
    
    .cta-section h2 {
      font-size: 34px;
      font-weight: 700;
      margin-bottom: 16px;
    }
    
    .cta-section p {
      color: rgba(255,255,255,0.75);
      font-size: 18px;
      margin-bottom: 36px;
    }
    
    .btn-light {
      background: white;
      color: var(--primary);
      padding: 16px 40px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
    }
    
    .btn-light:hover {
      background: #f0f2ff;
      transform: scale(1.03);
    }
    
    /* 页脚 */
    .footer {
      background: #1F2329;
      color: rgba(255,255,255,0.7);
      padding: 60px 0 30px;
    }
    
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      margin-bottom: 40px;
    }
    
    .footer-logo {
      font-size: 20px;
      font-weight: 700;
      color: white;
      margin-bottom: 12px;
    }
    
    .footer-desc {
      font-size: 14px;
      line-height: 1.7;
    }
    
    .footer h4 {
      color: white;
      font-weight: 600;
      margin-bottom: 16px;
      font-size: 16px;
    }
    
    .footer ul {
      list-style: none;
    }
    
    .footer li {
      margin-bottom: 10px;
      font-size: 14px;
    }
    
    .footer a:hover {
      color: white;
    }
    
    .copyright {
      border-top: 1px solid rgba(255,255,255,0.1);
      padding-top: 24px;
      text-align: center;
      font-size: 13px;
      color: rgba(255,255,255,0.5);
    }
    
    @media (max-width: 767px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }