/* roulang page: index */
/* 自定义设计变量与全局重置 */
    :root {
      --primary: #0A2540;
      --secondary: #00C9A7;
      --secondary-hover: #00A88C;
      --bg: #F7F9FC;
      --card-bg: #FFFFFF;
      --text-main: #2D3748;
      --text-muted: #718096;
      --border-light: #E2E8F0;
      --shadow-sm: 0 4px 20px rgba(10,37,64,0.06);
      --shadow-md: 0 8px 30px rgba(10,37,64,0.12);
      --radius-card: 12px;
      --radius-btn: 8px;
      --transition: 0.3s ease;
    }
    * {
      box-sizing: border-box;
    }
    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      background-color: var(--bg);
      color: var(--text-main);
      line-height: 1.6;
      margin: 0;
      padding: 0;
      scroll-behavior: smooth;
    }
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
    }
    /* 导航样式 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 72px;
      background: white;
      border-bottom: 1px solid var(--border-light);
      z-index: 1000;
      display: flex;
      align-items: center;
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-size: 1.5rem;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: -0.5px;
    }
    .logo span {
      color: var(--secondary);
    }
    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
    }
    .nav-links a {
      color: var(--primary);
      font-weight: 500;
      font-size: 1rem;
      text-decoration: none;
      position: relative;
      padding: 0.25rem 0;
      transition: color 0.2s;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--secondary);
      transition: width 0.3s ease;
    }
    .nav-links a:hover {
      color: var(--secondary);
    }
    .nav-links a:hover::after {
      width: 100%;
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: none;
      border: none;
      padding: 4px;
    }
    .hamburger span {
      width: 25px;
      height: 3px;
      background: var(--primary);
      border-radius: 3px;
      transition: 0.3s;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 72px;
      left: 0;
      width: 100%;
      background: white;
      flex-direction: column;
      padding: 1.5rem;
      border-bottom: 1px solid var(--border-light);
      z-index: 999;
    }
    .mobile-menu a {
      padding: 0.75rem 0;
      font-size: 1.2rem;
      color: var(--primary);
      border-bottom: 1px solid #f0f0f0;
      text-decoration: none;
      font-weight: 500;
    }
    /* 按钮系统 */
    .btn-primary {
      background: var(--secondary);
      color: white;
      font-weight: 600;
      border-radius: var(--radius-btn);
      padding: 14px 32px;
      border: none;
      cursor: pointer;
      transition: background 0.3s, transform 0.2s;
      display: inline-block;
      text-decoration: none;
      text-align: center;
    }
    .btn-primary:hover {
      background: var(--secondary-hover);
      transform: scale(1.02);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      font-weight: 600;
      border-radius: var(--radius-btn);
      padding: 14px 32px;
      cursor: pointer;
      transition: background 0.3s, color 0.3s;
      display: inline-block;
      text-decoration: none;
      text-align: center;
    }
    .btn-outline:hover {
      background: rgba(10,37,64,0.1);
    }
    /* 卡片样式 */
    .card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      padding: 32px;
      transition: box-shadow 0.3s, transform 0.3s;
    }
    .card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-4px);
    }
    /* 板块间距 */
    section {
      padding: 100px 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 70px 0;
      }
    }
    /* Hero 背景与遮罩 */
    .hero-bg {
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      position: relative;
    }
    .hero-overlay {
      background: linear-gradient(135deg, rgba(10,37,64,0.85) 0%, rgba(10,37,64,0.6) 100%);
      min-height: 100vh;
      display: flex;
      align-items: center;
    }
    /* 数据看板深色条 */
    .stats-band {
      background: var(--primary);
      color: white;
      padding: 60px 0;
    }
    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 20px 0;
      cursor: pointer;
    }
    .faq-question {
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.4s;
      color: #4A5568;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 12px;
    }
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }
    .faq-icon {
      transition: transform 0.3s;
      font-size: 1.5rem;
      color: var(--secondary);
    }
    /* 页脚 */
    footer {
      background: var(--primary);
      color: white;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 2rem;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }
    /* 动画工具 */
    .fade-up {
      opacity: 0;
      transform: translateY(30px);
      transition: opacity 0.6s ease, transform 0.6s ease;
    }
    .fade-up.visible {
      opacity: 1;
      transform: translateY(0);
    }