/* roulang page: index */
:root {
      --primary: #E53935;
      --primary-dark: #C62828;
      --secondary: #FFB300;
      --bg-page: #FFFFFF;
      --bg-alt: #F8F9FA;
      --text-heading: #111827;
      --text-body: #4B5563;
      --text-muted: #9CA3AF;
      --border-light: #E5E7EB;
      --shadow-card: 0 4px 12px rgba(0,0,0,0.05);
      --radius-card: 12px;
      --radius-btn: 8px;
    }

    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
      background-color: var(--bg-page);
      color: var(--text-body);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }

    img {
      max-width: 100%;
      height: auto;
      display: block;
    }

    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s ease, background-color 0.2s ease;
    }

    .container {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 1.5rem;
      padding-right: 1.5rem;
    }

    /* 导航样式 */
    .header {
      position: sticky;
      top: 0;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(8px);
      border-bottom: 1px solid var(--border-light);
      z-index: 50;
      padding: 1rem 0;
    }

    .nav-link {
      font-size: 1rem;
      font-weight: 500;
      color: var(--text-body);
      padding: 0.5rem 0;
      position: relative;
      transition: color 0.2s;
    }

    .nav-link:hover {
      color: var(--primary);
    }

    .nav-link.active {
      color: var(--primary);
      font-weight: 600;
    }

    .nav-link.active::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 100%;
      height: 2px;
      background-color: var(--primary);
      border-radius: 2px;
    }

    /* 汉堡菜单全屏覆盖 */
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: rgba(255,255,255,0.96);
      backdrop-filter: blur(12px);
      flex-direction: column;
      align-items: center;
      justify-content: center;
      z-index: 100;
      gap: 2rem;
    }

    .mobile-menu a {
      font-size: 1.8rem;
      font-weight: 500;
      color: var(--text-heading);
    }

    .mobile-menu a:hover {
      color: var(--primary);
    }

    #menu-toggle:checked ~ .mobile-menu {
      display: flex;
    }

    /* 按钮 */
    .btn-primary {
      background-color: var(--primary);
      color: white;
      border: none;
      padding: 0.75rem 1.5rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1rem;
      transition: background-color 0.2s, transform 0.1s;
      display: inline-block;
      text-align: center;
    }

    .btn-primary:hover {
      background-color: var(--primary-dark);
    }

    .btn-outline {
      background: transparent;
      color: var(--primary);
      border: 1.5px solid var(--primary);
      padding: 0.75rem 1.5rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1rem;
      transition: background-color 0.2s, color 0.2s;
    }

    .btn-outline:hover {
      background-color: rgba(229, 57, 53, 0.05);
    }

    /* 卡片悬停 */
    .feature-card {
      background: white;
      border: 1px solid var(--border-light);
      border-radius: var(--radius-card);
      transition: border-color 0.2s, box-shadow 0.2s;
      padding: 2rem;
    }

    .feature-card:hover {
      border-color: var(--primary);
      box-shadow: var(--shadow-card);
    }

    .pricing-card {
      background: white;
      border: 1px solid var(--border-light);
      border-radius: var(--radius-card);
      padding: 2rem;
      transition: box-shadow 0.2s;
    }

    .pricing-card.recommended {
      border: 2px solid var(--primary);
      box-shadow: 0 10px 20px rgba(229,57,53,0.08);
    }

    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 1.25rem 0;
    }

    .faq-question {
      font-weight: 600;
      color: var(--text-heading);
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      color: var(--text-body);
    }

    .faq-item.open .faq-answer {
      max-height: 200px;
      padding-top: 1rem;
    }

    .footer-link:hover {
      color: white;
      text-decoration: underline;
    }

    @media (max-width: 768px) {
      .container {
        padding-left: 1rem;
        padding-right: 1rem;
      }
      .hero-title {
        font-size: 2.25rem;
        line-height: 2.8rem;
      }
      .section-title {
        font-size: 1.75rem;
        line-height: 2.4rem;
      }
    }

    /* 自定义滚动卡片 */
    .scroll-cards {
      display: flex;
      gap: 1.5rem;
      overflow-x: auto;
      padding-bottom: 1rem;
      scroll-snap-type: x mandatory;
    }
    .scroll-card {
      min-width: 280px;
      background: #F9FAFB;
      border-radius: 16px;
      padding: 2rem;
      scroll-snap-align: start;
      flex-shrink: 0;
    }