/* roulang page: index */
:root {
      --primary: #0F172A;
      --accent: #F59E0B;
      --accent-hover: #D97706;
      --soft: #F8FAFC;
      --muted: #475569;
      --subtle: #94A3B8;
      --borderlight: #E2E8F0;
      --positive: #10B981;
      --negative: #EF4444;
      --font-sans: 'Inter', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
    }
    * {
      box-sizing: border-box;
    }
    body {
      font-family: var(--font-sans);
      background-color: #fff;
      color: var(--primary);
      margin: 0;
      padding: 0;
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      color: inherit;
      text-decoration: none;
      transition: color 0.2s ease;
    }
    button, input, textarea {
      font-family: inherit;
      outline: none;
    }
    /* 导航玻璃效果与滚动切换 */
    .glass-nav {
      background: rgba(255,255,255,0.2);
      backdrop-filter: blur(16px);
      -webkit-backdrop-filter: blur(16px);
      border-bottom: 1px solid rgba(255,255,255,0.25);
      transition: background 0.3s ease, backdrop-filter 0.3s ease, box-shadow 0.3s ease, border-color 0.3s ease;
    }
    .nav-scrolled {
      background: rgba(255,255,255,0.95);
      backdrop-filter: none;
      -webkit-backdrop-filter: none;
      box-shadow: 0 4px 20px rgba(0,0,0,0.05);
      border-bottom: 1px solid #E2E8F0;
    }
    .nav-link {
      position: relative;
      font-weight: 500;
      color: #0F172A;
      opacity: 0.85;
      transition: opacity 0.2s;
    }
    .nav-link:hover {
      opacity: 1;
    }
    .nav-link::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: -4px;
      width: 0;
      height: 2px;
      background-color: var(--accent);
      transition: width 0.25s ease;
    }
    .nav-link:hover::after {
      width: 100%;
    }
    /* 移动端菜单 */
    .mobile-menu {
      background: rgba(255,255,255,0.96);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
    }
    /* 数字强调 */
    .stat-number {
      font-family: 'Inter', 'DIN Alternate', 'Menlo', monospace;
      font-weight: 800;
      letter-spacing: -0.03em;
    }
    /* 手风琴动画 */
    .faq-content {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease;
    }
    .faq-item.open .faq-content {
      max-height: 200px;
    }
    .faq-icon {
      transition: transform 0.3s ease;
    }
    .faq-item.open .faq-icon {
      transform: rotate(180deg);
    }
    /* 输入框底部线条 */
    .input-line {
      border: 0;
      border-bottom: 2px solid #E2E8F0;
      background: transparent;
      padding: 12px 0;
      width: 100%;
      transition: border-color 0.25s;
    }
    .input-line:focus {
      border-bottom-color: #F59E0B;
    }
    /* 自定义滚动条 */
    ::-webkit-scrollbar {
      width: 6px;
    }
    ::-webkit-scrollbar-track {
      background: #f1f5f9;
    }
    ::-webkit-scrollbar-thumb {
      background: #cbd5e1;
      border-radius: 3px;
    }