/* roulang page: index */
/* ----- 设计系统变量 ----- */
    :root {
      --primary: #7B2FF7;
      --primary-dark: #6818D4;
      --accent: #00F0FF;
      --deep-bg: #0B0C10;
      --light-bg: #F4F5FA;
      --card-bg: #FFFFFF;
      --text-main: #0B0C10;
      --text-body: #2D3142;
      --text-muted: #6C7280;
      --border-light: #E4E6F0;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-tag: 6px;
      --shadow-sm: 0 4px 20px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 30px rgba(0,0,0,0.08);
      --transition: 0.25s ease;
      --container-max: 1280px;
      --gap-section: 100px;
    }
    
    /* ----- 基础重置与排版 ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    
    html {
      scroll-behavior: smooth;
    }
    
    body {
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', system-ui, -apple-system, sans-serif;
      background-color: #FFFFFF;
      color: var(--text-body);
      line-height: 1.75;
      font-size: 16px;
      font-weight: 400;
      -webkit-font-smoothing: antialiased;
    }
    
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }
    
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      font-weight: 600;
      transition: all var(--transition);
      border-radius: var(--radius-btn);
    }
    
    .container {
      width: 100%;
      max-width: var(--container-max);
      margin-left: auto;
      margin-right: auto;
      padding-left: 24px;
      padding-right: 24px;
    }
    
    /* 标题层级 */
    h1, h2, h3, .h1, .h2, .h3 {
      font-weight: 700;
      color: var(--text-main);
    }
    
    h1, .h1 {
      font-size: clamp(36px, 5vw, 48px);
      line-height: 1.2;
      letter-spacing: -0.5px;
    }
    
    h2, .h2 {
      font-size: clamp(28px, 4vw, 32px);
      line-height: 1.3;
      margin-bottom: 12px;
    }
    
    h3, .h3 {
      font-size: clamp(20px, 3vw, 24px);
      line-height: 1.4;
    }
    
    .text-muted {
      color: var(--text-muted);
    }
    
    .section {
      padding: var(--gap-section) 0;
    }
    
    /* 按钮系统 */
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 12px 28px;
      box-shadow: 0 4px 12px rgba(123,47,247,0.3);
    }
    
    .btn-primary:hover {
      background: var(--primary-dark);
      box-shadow: 0 6px 16px rgba(123,47,247,0.5), 0 0 12px var(--accent);
      transform: translateY(-1px);
    }
    
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      padding: 10px 26px;
    }
    
    .btn-outline:hover {
      background: rgba(123,47,247,0.08);
      border-color: var(--primary-dark);
    }
    
    .btn-light {
      background: white;
      color: var(--primary);
      padding: 12px 30px;
      font-weight: 700;
    }
    
    .btn-light:hover {
      background: var(--light-bg);
    }
    
    /* 卡片基础 */
    .card {
      background: var(--card-bg);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      transition: all var(--transition);
    }
    
    .card:hover {
      box-shadow: var(--shadow-md);
      border-color: var(--accent);
      transform: translateY(-4px);
    }
    
    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(11,12,16,0.92);
      backdrop-filter: blur(12px);
      z-index: 1000;
      border-bottom: 1px solid rgba(255,255,255,0.05);
    }
    
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 70px;
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }
    
    .logo {
      display: flex;
      align-items: center;
      gap: 8px;
      font-size: 24px;
      font-weight: 700;
      color: white;
      letter-spacing: 1px;
    }
    
    .logo i {
      color: var(--accent);
      font-size: 28px;
    }
    
    .nav-menu {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    
    .nav-link {
      color: #ccc;
      font-weight: 500;
      font-size: 15px;
      position: relative;
    }
    
    .nav-link:hover, .nav-link.active {
      color: white;
    }
    
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent);
      transition: width var(--transition);
    }
    
    .nav-link:hover::after, .nav-link.active::after {
      width: 100%;
    }
    
    .hamburger {
      display: none;
      font-size: 28px;
      color: white;
      background: none;
      border: none;
    }
    
    .mobile-menu {
      display: none;
    }
    
    /* Hero 首屏 */
    .hero {
      background: var(--deep-bg);
      color: white;
      padding: 140px 0 100px;
      position: relative;
      overflow: hidden;
    }
    
    .hero::after {
      content: '';
      position: absolute;
      bottom: 0;
      right: 0;
      width: 300px;
      height: 300px;
      background: radial-gradient(circle, rgba(0,240,255,0.12) 0%, transparent 70%);
      pointer-events: none;
    }
    
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
    }
    
    .hero-text {
      flex: 1;
    }
    
    .hero-text h1 {
      color: white;
      margin-bottom: 20px;
    }
    
    .hero-subtitle {
      font-size: 18px;
      color: #B0B8C5;
      margin-bottom: 32px;
      line-height: 1.6;
    }
    
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    
    .hero-image {
      flex: 1;
      display: flex;
      justify-content: center;
    }
    
    .hero-image img {
      max-height: 380px;
      border-radius: 20px;
      box-shadow: 0 20px 40px rgba(0,0,0,0.6);
      border: 1px solid rgba(255,255,255,0.1);
    }
    
    /* 核心优势 */
    .advantages-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 32px;
      margin-top: 40px;
    }
    
    .adv-card {
      padding: 32px 24px;
      text-align: center;
    }
    
    .adv-icon {
      font-size: 40px;
      color: var(--accent);
      margin-bottom: 20px;
    }
    
    /* 功能分组左右交替 */
    .feature-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 80px;
    }
    
    .feature-row.reverse {
      flex-direction: row-reverse;
    }
    
    .feature-content, .feature-img {
      flex: 1;
    }
    
    .feature-img img {
      border-radius: 16px;
      box-shadow: var(--shadow-md);
      border: 1px solid var(--border-light);
    }
    
    .feature-list {
      list-style: none;
      margin-top: 20px;
    }
    
    .feature-list li {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: 12px;
      color: var(--text-body);
    }
    
    .feature-list i {
      color: var(--primary);
      font-size: 18px;
    }
    
    /* 场景卡片 */
    .scenario-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 32px;
      margin-top: 40px;
    }
    
    .scenario-card {
      background: #F8F9FC;
      padding: 32px 24px;
      border-radius: var(--radius-card);
      transition: all var(--transition);
    }
    
    .scenario-card:hover {
      background: white;
      box-shadow: var(--shadow-md);
    }
    
    /* 数据案例 */
    .stats-bar {
      display: flex;
      justify-content: space-around;
      text-align: center;
      margin: 40px 0;
      flex-wrap: wrap;
    }
    
    .stat-item h3 {
      color: var(--primary);
      font-size: 40px;
      margin-bottom: 8px;
    }
    
    .case-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 32px;
      margin-top: 40px;
    }
    
    .case-card {
      padding: 28px;
      display: flex;
      gap: 24px;
      align-items: center;
    }
    
    .case-logo {
      width: 80px;
      height: 80px;
      background: var(--light-bg);
      border-radius: 20px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 32px;
      color: var(--primary);
    }
    
    /* FAQ 手风琴 */
    .faq-list {
      max-width: 800px;
      margin: 40px auto 0;
    }
    
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 20px 0;
    }
    
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 700;
      font-size: 18px;
      cursor: pointer;
      color: var(--text-main);
    }
    
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease;
      color: var(--text-body);
      padding-right: 30px;
    }
    
    .faq-item.active .faq-answer {
      max-height: 150px;
      margin-top: 12px;
    }
    
    .faq-item.active .faq-question i {
      color: var(--accent);
    }
    
    /* CTA 区块 */
    .cta-section {
      background: var(--deep-bg);
      color: white;
      text-align: center;
      padding: 90px 0;
      position: relative;
    }
    
    .cta-section h2 {
      color: white;
    }
    
    /* 页脚 */
    .footer {
      background: #0B0C10;
      color: #B0B8C5;
      padding: 60px 0 30px;
    }
    
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      margin-bottom: 40px;
    }
    
    .footer a {
      color: #B0B8C5;
    }
    
    .footer a:hover {
      color: white;
    }
    
    .copyright {
      border-top: 1px solid rgba(255,255,255,0.08);
      padding-top: 24px;
      text-align: center;
      font-size: 14px;
    }
    
    /* 响应式设计 */
    @media (max-width: 1024px) {
      .hero-grid, .feature-row {
        gap: 32px;
      }
      .advantages-grid, .scenario-grid {
        grid-template-columns: repeat(2, 1fr);
      }
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }
    
    @media (max-width: 768px) {
      .nav-menu {
        display: none;
      }
      .hamburger {
        display: block;
      }
      .mobile-menu {
        display: none;
        position: fixed;
        top: 70px;
        left: 0;
        width: 100%;
        background: rgba(11,12,16,0.98);
        backdrop-filter: blur(20px);
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        border-top: 1px solid var(--accent);
      }
      .mobile-menu.open {
        display: flex;
      }
      .hero-grid {
        flex-direction: column;
      }
      .advantages-grid, .scenario-grid, .case-grid {
        grid-template-columns: 1fr;
      }
      .feature-row, .feature-row.reverse {
        flex-direction: column;
      }
      .stats-bar {
        gap: 24px;
      }
      .footer-grid {
        grid-template-columns: 1fr;
      }
      .hero {
        padding: 120px 0 80px;
      }
    }
    
    @media (max-width: 520px) {
      .hero-buttons {
        flex-direction: column;
        align-items: flex-start;
      }
    }