/* roulang page: index */
/* ===== 自定义CSS变量与深度视觉覆盖 ===== */
    :root {
      --deep-purple: #1A0A2E;
      --bg-dark: #0D0B1E;
      --bg-card: rgba(255, 255, 255, 0.04);
      --accent-green: #00F0B5;
      --star-gold: #FFD766;
      --text-primary: #FFFFFF;
      --text-secondary: #C8C3E0;
      --text-muted: #7B7499;
      --border-light: rgba(255, 255, 255, 0.06);
      --shadow-green: 0 8px 32px rgba(0, 240, 181, 0.12);
      --radius-card: 16px;
      --radius-btn: 50px;
      --transition-smooth: all 0.25s ease;
    }
    
    * {
      box-sizing: border-box;
    }
    
    body {
      font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', system-ui, sans-serif;
      background-color: var(--bg-dark);
      color: var(--text-secondary);
      line-height: 1.75;
      margin: 0;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    
    /* 容器栅格 */
    .container-custom {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }
    
    /* 板块间距 */
    section {
      padding: 80px 0;
    }
    @media (min-width: 1024px) {
      section {
        padding: 120px 0;
      }
    }
    
    /* 导航沉浸式 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 72px;
      background: rgba(13, 11, 30, 0.88);
      backdrop-filter: blur(14px);
      -webkit-backdrop-filter: blur(14px);
      z-index: 50;
      border-bottom: 1px solid var(--border-light);
      display: flex;
      align-items: center;
      transition: var(--transition-smooth);
    }
    
    .nav-link {
      color: var(--text-secondary);
      font-weight: 500;
      padding: 8px 4px;
      margin: 0 14px;
      position: relative;
      transition: color 0.2s;
      text-decoration: none;
    }
    .nav-link:hover, .nav-link.active {
      color: var(--accent-green);
    }
    .nav-link.active::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 100%;
      height: 2px;
      background: var(--accent-green);
      border-radius: 2px;
    }
    
    /* 汉堡菜单 */
    .mobile-menu {
      background: rgba(13, 11, 30, 0.96);
      backdrop-filter: blur(20px);
    }
    
    /* 按钮系统 */
    .btn-primary {
      background: var(--accent-green);
      color: #0D0B1E;
      font-weight: 600;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      border: none;
      cursor: pointer;
      transition: all 0.3s;
      box-shadow: 0 0 18px rgba(0,240,181,0.25);
      display: inline-block;
      text-align: center;
    }
    .btn-primary:hover {
      background: #00e6a6;
      box-shadow: 0 0 28px rgba(0,240,181,0.5);
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--accent-green);
      color: var(--accent-green);
      font-weight: 600;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      cursor: pointer;
      transition: all 0.3s;
      display: inline-block;
      text-align: center;
    }
    .btn-outline:hover {
      background: rgba(0,240,181,0.08);
      border-color: #00e6a6;
    }
    
    /* 卡片与hover */
    .feature-card, .advantage-card, .case-card {
      background: rgba(255,255,255,0.03);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-card);
      transition: var(--transition-smooth);
      backdrop-filter: blur(4px);
    }
    .feature-card:hover, .advantage-card:hover {
      border-color: var(--accent-green);
      box-shadow: var(--shadow-green);
      transform: translateY(-4px);
    }
    
    /* 数字动画 */
    .counter-num {
      font-feature-settings: "tnum";
      font-variant-numeric: tabular-nums;
    }
    
    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      cursor: pointer;
      transition: color 0.2s;
    }
    .faq-question:hover {
      color: var(--accent-green);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.3s;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 20px;
    }
    
    /* 装饰线条 */
    .decor-line {
      background: linear-gradient(90deg, transparent, rgba(0,240,181,0.4), transparent);
      height: 1px;
      width: 100%;
    }
    
    /* 图片容器 */
    .img-cover {
      object-fit: cover;
      width: 100%;
      height: 100%;
      display: block;
    }