/* roulang page: index */
:root {
      --primary: #1A56DB;
      --primary-hover: #1E40AF;
      --secondary: #0EA5E9;
      --accent: #F59E0B;
      --accent-hover: #D97706;
      --bg: #F8FAFC;
      --card-bg: #FFFFFF;
      --text-main: #0F172A;
      --text-body: #334155;
      --text-muted: #64748B;
      --border: #E2E8F0;
      --success: #10B981;
      --deep-footer: #0F172A;
      --footer-text: #CBD5E1;
      
      --radius-sm: 8px;
      --radius: 12px;
      --radius-lg: 16px;
      --shadow-card: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
      --shadow-hover: 0 10px 25px rgba(0,0,0,0.08), 0 4px 10px rgba(0,0,0,0.04);
      --transition: all 0.2s ease;
      
      --section-gap: 100px;
    }

    * {
      box-sizing: border-box;
    }

    body {
      font-family: 'Inter', 'Noto Sans SC', system-ui, -apple-system, sans-serif;
      background-color: var(--bg);
      color: var(--text-body);
      line-height: 1.6;
      margin: 0;
      padding: 0;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

    /* 容器最大宽度与居中 */
    .container-custom {
      max-width: 1200px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 20px;
      padding-right: 20px;
    }

    /* 板块间距 */
    .section-spacing {
      margin-top: var(--section-gap);
      margin-bottom: var(--section-gap);
    }
    @media (max-width: 768px) {
      .section-spacing {
        margin-top: 64px;
        margin-bottom: 64px;
      }
    }

    /* 导航阴影增强 */
    .nav-scrolled {
      box-shadow: 0 2px 8px rgba(0,0,0,0.06);
    }

    /* 按钮基础过渡 */
    .btn-primary {
      background-color: var(--primary);
      color: white;
      border-radius: var(--radius-sm);
      padding: 14px 32px;
      font-weight: 600;
      font-size: 16px;
      letter-spacing: 0.3px;
      transition: var(--transition);
      display: inline-block;
      text-align: center;
      border: none;
      cursor: pointer;
    }
    .btn-primary:hover {
      background-color: var(--primary-hover);
      box-shadow: 0 6px 16px rgba(26,86,219,0.25);
      transform: translateY(-1px);
    }

    .btn-secondary {
      background: transparent;
      color: var(--primary);
      border: 2px solid var(--primary);
      border-radius: var(--radius-sm);
      padding: 14px 32px;
      font-weight: 600;
      font-size: 16px;
      letter-spacing: 0.3px;
      transition: var(--transition);
      display: inline-block;
      text-align: center;
      cursor: pointer;
    }
    .btn-secondary:hover {
      background-color: #EFF6FF;
      border-color: var(--primary-hover);
      color: var(--primary-hover);
      transform: translateY(-1px);
    }

    .btn-accent {
      background-color: var(--accent);
      color: #0F172A;
      border-radius: var(--radius-sm);
      padding: 14px 32px;
      font-weight: 600;
      font-size: 16px;
      letter-spacing: 0.3px;
      transition: var(--transition);
      display: inline-block;
      text-align: center;
      border: none;
      cursor: pointer;
      box-shadow: 0 4px 10px rgba(245,158,11,0.3);
    }
    .btn-accent:hover {
      background-color: var(--accent-hover);
      box-shadow: 0 8px 18px rgba(217,119,6,0.4);
      transform: translateY(-2px);
    }

    /* 卡片样式 */
    .card {
      background: var(--card-bg);
      border-radius: var(--radius);
      box-shadow: var(--shadow-card);
      border: 1px solid var(--border);
      padding: 28px 28px;
      transition: var(--transition);
      height: 100%;
      display: flex;
      flex-direction: column;
    }
    .card:hover {
      box-shadow: var(--shadow-hover);
      border-color: var(--primary);
      transform: translateY(-4px);
    }

    /* 功能卡片图标容器 */
    .feature-icon {
      font-size: 40px;
      color: var(--primary);
      margin-bottom: 16px;
      transition: transform 0.2s ease;
    }
    .card:hover .feature-icon {
      transform: scale(1.05);
    }

    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border);
      padding: 18px 0;
    }
    .faq-question {
      font-weight: 600;
      font-size: 18px;
      color: var(--text-main);
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      transition: color 0.2s;
      background: none;
      border: none;
      width: 100%;
      text-align: left;
      padding: 8px 0;
    }
    .faq-question:hover {
      color: var(--primary);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease, padding 0.35s ease;
      color: #475569;
      font-size: 15px;
      line-height: 1.6;
      background-color: #F8FAFC;
      border-radius: 6px;
      padding: 0 12px;
      margin-top: 4px;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 14px 12px;
    }
    .faq-arrow {
      transition: transform 0.25s ease;
      font-size: 16px;
      color: var(--text-muted);
    }
    .faq-item.active .faq-arrow {
      transform: rotate(180deg);
      color: var(--primary);
    }

    /* 价格卡片高亮 */
    .pricing-highlight {
      border: 2px solid var(--primary);
      transform: scale(1.02);
      box-shadow: 0 8px 28px rgba(26,86,219,0.12);
    }
    @media (max-width: 768px) {
      .pricing-highlight {
        transform: none;
      }
    }

    /* 移动端汉堡菜单 */
    .mobile-menu {
      display: none;
      flex-direction: column;
      background: white;
      position: absolute;
      top: 72px;
      left: 0;
      width: 100%;
      box-shadow: 0 8px 20px rgba(0,0,0,0.08);
      padding: 24px 20px;
      z-index: 49;
    }
    .mobile-menu.open {
      display: flex;
    }
    .mobile-menu a {
      display: block;
      padding: 16px 12px;
      font-size: 18px;
      font-weight: 500;
      color: var(--text-main);
      border-bottom: 1px solid var(--border);
      text-decoration: none;
    }
    .mobile-menu a:last-child {
      border-bottom: none;
    }

    /* 图片圆角与阴影 */
    .img-rounded {
      border-radius: var(--radius-lg);
      box-shadow: 0 6px 18px rgba(0,0,0,0.08);
      width: 100%;
      height: auto;
      object-fit: cover;
    }