/* roulang page: index */
:root {
      --primary: #C49A2C;
      --primary-soft: rgba(196, 154, 44, 0.08);
      --primary-glow: rgba(196, 154, 44, 0.25);
      --accent: #E87722;
      --deep-rock: #2B2B2B;
      --industrial-gray: #6B6B6B;
      --warm-white: #FDF9F2;
      --text-body: #4A4A4A;
      --border-light: #E8E0D5;
      --shadow-sm: 0 4px 12px rgba(0,0,0,0.03);
      --shadow-md: 0 8px 30px rgba(0,0,0,0.06);
      --shadow-hover: 0 16px 36px rgba(0,0,0,0.09);
      --radius-card: 16px;
      --radius-btn: 10px;
      --transition: 0.25s ease;
      --font-heading: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: var(--font-heading);
      background-color: var(--warm-white);
      color: var(--text-body);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 2rem;
      padding-right: 2rem;
    }
    @media (max-width: 768px) {
      .container {
        padding-left: 1.25rem;
        padding-right: 1.25rem;
      }
    }
    /* 导航固定 */
    .main-header {
      position: sticky;
      top: 0;
      z-index: 50;
      background: rgba(253, 249, 242, 0.96);
      backdrop-filter: blur(6px);
      box-shadow: 0 2px 12px rgba(0,0,0,0.02);
      transition: box-shadow 0.3s;
    }
    .main-header.scrolled {
      box-shadow: 0 6px 18px rgba(0,0,0,0.06);
    }
    .top-bar {
      background: var(--deep-rock);
      color: #F5F0E8;
      font-size: 0.8rem;
      padding: 6px 0;
      letter-spacing: 0.3px;
    }
    .brand-text {
      font-weight: 700;
      color: var(--primary);
      letter-spacing: -0.3px;
    }
    .brand-accent {
      color: var(--accent);
      font-weight: 700;
      margin-left: 2px;
    }
    .nav-link {
      color: var(--deep-rock);
      font-weight: 500;
      transition: color 0.2s;
      position: relative;
    }
    .nav-link:hover {
      color: var(--primary);
    }
    .mobile-menu {
      display: none;
    }
    @media (max-width: 768px) {
      .desktop-nav {
        display: none;
      }
      .mobile-menu {
        display: block;
      }
    }
    /* 按钮 */
    .btn-primary {
      background: var(--primary);
      color: white;
      border-radius: var(--radius-btn);
      padding: 0.85rem 2rem;
      font-weight: 600;
      transition: background 0.25s, box-shadow 0.25s, transform 0.2s;
      box-shadow: 0 4px 14px rgba(196,154,44,0.25);
    }
    .btn-primary:hover {
      background: #d4a832;
      box-shadow: 0 8px 22px rgba(196,154,44,0.4);
      transform: translateY(-1px);
    }
    .btn-outline {
      border: 2px solid var(--deep-rock);
      color: var(--deep-rock);
      background: transparent;
      border-radius: var(--radius-btn);
      padding: 0.8rem 1.8rem;
      font-weight: 600;
      transition: 0.25s;
    }
    .btn-outline:hover {
      background: var(--deep-rock);
      color: white;
    }
    .btn-accent {
      background: var(--accent);
      color: white;
      border-radius: 30px;
      padding: 0.9rem 2.2rem;
      font-weight: 700;
      transition: transform 0.2s, background 0.2s;
    }
    .btn-accent:hover {
      background: #d96a1a;
      transform: scale(1.03);
    }
    /* 卡片悬浮 */
    .card-hover {
      transition: transform var(--transition), box-shadow var(--transition);
    }
    .card-hover:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
    }
    /* 指标数字动画示意 */
    .counter {
      font-weight: 800;
      color: var(--accent);
      font-size: 2.8rem;
      line-height: 1.2;
    }
    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      cursor: pointer;
      font-weight: 600;
      padding: 1.2rem 0;
      display: flex;
      align-items: center;
      gap: 12px;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease;
      padding-left: 2.5rem;
      color: #5A5A5A;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 1.2rem;
    }
    .faq-item.active .faq-question {
      color: var(--primary);
    }
    /* 装饰对比竖线 */
    .compare-traditional {
      border-left: 4px solid #B0B0B0;
      background: #F2F2F2;
    }
    .compare-sun {
      border-left: 4px solid var(--primary);
      background: rgba(196,154,44,0.06);
    }