/* roulang page: index */
/* 设计变量与全局重置 */
    :root {
      --primary: #E8452D;
      --primary-hover: #C93020;
      --secondary: #0F1A2E;
      --accent: #F5A623;
      --bg-warm: #F7F5F2;
      --card-bg: #FFFFFF;
      --text-main: #1E2330;
      --text-muted: #5A6070;
      --border-light: rgba(15, 26, 46, 0.08);
      --shadow-sm: 0 4px 20px rgba(15, 26, 46, 0.06);
      --shadow-hover: 0 8px 30px rgba(232, 69, 45, 0.12);
      --radius-lg: 16px;
      --radius-btn: 50px;
      --transition: 0.3s ease;
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: system-ui, -apple-system, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      background-color: var(--bg-warm);
      color: var(--text-main);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      transition: var(--transition);
    }
    /* 容器 */
    .container-custom {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }
    @media (max-width: 768px) {
      .container-custom {
        padding: 0 16px;
      }
    }
    /* 导航 */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 50;
      background: #FFFFFF;
      height: 72px;
      display: flex;
      align-items: center;
      border-bottom: 1px solid var(--border-light);
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      display: flex;
      align-items: center;
      gap: 10px;
      font-weight: 700;
      font-size: 1.5rem;
      color: var(--secondary);
    }
    .logo i {
      font-size: 2rem;
      color: var(--primary);
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-main);
      position: relative;
      padding: 8px 0;
      transition: color 0.2s;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 3px;
      background: var(--primary);
      transition: width 0.25s ease;
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .nav-links a:hover::after {
      width: 100%;
    }
    .hamburger {
      display: none;
      font-size: 1.8rem;
      color: var(--secondary);
      background: none;
      border: none;
    }
    /* 移动端导航抽屉 */
    .mobile-menu {
      position: fixed;
      top: 0;
      right: -100%;
      width: 75%;
      max-width: 300px;
      height: 100vh;
      background: #FFFFFF;
      box-shadow: -5px 0 20px rgba(0,0,0,0.1);
      padding: 24px;
      transition: right 0.3s ease;
      z-index: 100;
      display: flex;
      flex-direction: column;
      gap: 24px;
    }
    .mobile-menu.active {
      right: 0;
    }
    .mobile-menu a {
      font-size: 1.2rem;
      font-weight: 600;
      color: var(--secondary);
      padding: 8px 0;
      border-bottom: 1px solid var(--border-light);
    }
    .overlay {
      position: fixed;
      inset: 0;
      background: rgba(15,26,46,0.5);
      z-index: 99;
      display: none;
    }
    .overlay.active {
      display: block;
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
      }
      .hamburger {
        display: block;
      }
    }
    /* 按钮 */
    .btn-primary {
      background: var(--primary);
      color: #fff;
      border: none;
      padding: 12px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      box-shadow: 0 4px 10px rgba(232,69,45,0.2);
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      transform: translateY(-2px);
      box-shadow: 0 8px 18px rgba(232,69,45,0.3);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--secondary);
      color: var(--secondary);
      padding: 12px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
    }
    .btn-outline:hover {
      background: var(--secondary);
      color: #fff;
    }
    /* 卡片通用 */
    .card {
      background: var(--card-bg);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      padding: 24px;
      height: 100%;
    }
    .card:hover {
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }
    /* 渐变动画背景 */
    .hero-gradient {
      background: linear-gradient(135deg, #0F1A2E 0%, #E8452D 100%);
      position: relative;
      overflow: hidden;
    }
    .hero-gradient::before {
      content: '';
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background-image: repeating-linear-gradient(45deg, rgba(255,255,255,0.03) 0px, rgba(255,255,255,0.03) 2px, transparent 2px, transparent 8px);
    }
    /* 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 18px 0;
    }
    .faq-question {
      display: flex;
      align-items: center;
      gap: 12px;
      font-weight: 600;
      cursor: pointer;
      font-size: 1.1rem;
    }
    .faq-question i {
      color: var(--primary);
      transition: transform 0.25s;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s;
      color: var(--text-muted);
      padding-left: 32px;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 12px;
    }
    .faq-item.active .faq-question i {
      transform: rotate(180deg);
    }
    /* 错落网格 */
    .stagger-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 24px;
    }
    .stagger-item:nth-child(1) { grid-column: span 1; }
    .stagger-item:nth-child(2) { grid-column: span 1; }
    .stagger-item:nth-child(3) { grid-column: span 1; }
    .stagger-item:nth-child(4) { grid-column: span 1; }
    @media (min-width: 769px) {
      .stagger-item:nth-child(1) { grid-column: span 1.2; }
      .stagger-item:nth-child(2) { grid-column: span 0.8; }
      .stagger-item:nth-child(3) { grid-column: span 0.8; }
      .stagger-item:nth-child(4) { grid-column: span 1.2; }
    }
    @media (max-width: 768px) {
      .stagger-grid {
        grid-template-columns: 1fr;
      }
    }
    /* 数据徽章 */
    .badge-stat {
      background: rgba(255,255,255,0.15);
      backdrop-filter: blur(4px);
      border-radius: 12px;
      padding: 12px 18px;
      color: white;
    }
    .badge-stat .number {
      font-size: 1.8rem;
      font-weight: 800;
      color: var(--accent);
      font-variant-numeric: tabular-nums;
    }