/* roulang page: index */
/* ========== 全局设计变量与重置 ========== */
    :root {
      --primary: #1A5F7A;
      --primary-deep: #0F3B4C;
      --cta: #E85D04;
      --cta-hover: #C94A00;
      --bg-page: #FAFBFB;
      --bg-card: #FFFFFF;
      --bg-alt: #F2F5F7;
      --text-main: #1A1A1A;
      --text-secondary: #4A4A4A;
      --text-muted: #6B7B83;
      --border-light: #E2E8EC;
      --footer-bg: #1A2B34;
      --footer-text: #B0BEC5;
      --radius-card: 12px;
      --radius-btn: 8px;
      --shadow-sm: 0 2px 12px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 24px rgba(0,0,0,0.08);
      --transition: 0.25s ease-out;
    }
    
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    
    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", "Inter", "SF Pro Display", system-ui, sans-serif;
      background-color: var(--bg-page);
      color: var(--text-main);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
    }
    
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    
    a {
      color: inherit;
      text-decoration: none;
    }
    
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
    }
    
    /* 导航栏 */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 50;
      background: white;
      height: 72px;
      box-shadow: 0 1px 8px rgba(0,0,0,0.04);
      display: flex;
      align-items: center;
    }
    
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    
    .logo {
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--primary);
      white-space: nowrap;
      letter-spacing: -0.5px;
    }
    
    .nav-links {
      display: flex;
      align-items: center;
      gap: 2rem;
    }
    
    .nav-links a {
      font-weight: 500;
      font-size: 1rem;
      color: var(--text-secondary);
      padding: 0.4rem 0;
      border-bottom: 2px solid transparent;
      transition: color var(--transition), border-color var(--transition);
    }
    
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
      border-bottom-color: var(--primary);
    }
    
    .btn-nav {
      background: var(--cta);
      color: white !important;
      padding: 0.5rem 1.4rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 0.9rem;
      transition: background var(--transition);
      border-bottom: none !important;
      display: inline-block;
    }
    .btn-nav:hover {
      background: var(--cta-hover);
      color: white !important;
      border-bottom: none !important;
    }
    
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: none;
      border: none;
      padding: 8px;
    }
    .hamburger span {
      width: 26px;
      height: 3px;
      background: var(--primary);
      border-radius: 2px;
      transition: 0.3s;
    }
    
    /* 移动端菜单 */
    .mobile-menu {
      position: fixed;
      top: 0;
      right: -100%;
      width: 80%;
      max-width: 320px;
      height: 100vh;
      background: white;
      box-shadow: -4px 0 24px rgba(0,0,0,0.1);
      display: flex;
      flex-direction: column;
      padding: 2rem;
      transition: right 0.35s ease;
      z-index: 100;
    }
    .mobile-menu.open {
      right: 0;
    }
    .mobile-menu a {
      font-size: 1.4rem;
      margin: 0.8rem 0;
      font-weight: 500;
      color: var(--text-main);
    }
    .mobile-menu .btn-nav {
      margin-top: 1.5rem;
      text-align: center;
    }
    
    /* Hero 双栏 */
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 3rem;
      align-items: center;
      padding: 3rem 0 4rem;
    }
    .hero-left {
      position: relative;
    }
    .hero-left::after {
      content: '';
      position: absolute;
      right: -20px;
      top: 0;
      height: 100%;
      width: 1px;
      background: var(--border-light);
      opacity: 0.6;
    }
    .hero-right img {
      border-radius: 16px;
      box-shadow: var(--shadow-md);
      width: 100%;
      object-fit: cover;
    }
    .stat-block {
      display: flex;
      gap: 2rem;
      margin: 2rem 0;
    }
    .stat-number {
      color: var(--cta);
      font-weight: 700;
      font-size: 2rem;
    }
    
    /* 板块标题 */
    .section-title {
      font-size: 2rem;
      font-weight: 600;
      margin-bottom: 1rem;
      color: var(--text-main);
    }
    .section-spacing {
      margin-top: 80px;
      margin-bottom: 48px;
    }
    
    /* 不规则网格卡片 */
    .advantage-grid {
      display: grid;
      grid-template-columns: 1fr 1.5fr 1fr;
      gap: 24px;
    }
    .card-adv {
      background: white;
      padding: 28px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      transition: transform var(--transition), box-shadow var(--transition);
    }
    .card-adv:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }
    
    /* 瀑布流双列 */
    .masonry-grid {
      columns: 2;
      column-gap: 24px;
    }
    .masonry-card {
      break-inside: avoid;
      margin-bottom: 32px;
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
    }
    .masonry-card img {
      width: 100%;
      height: auto;
      object-fit: cover;
    }
    .masonry-content {
      padding: 20px;
      border-top: 1px solid var(--border-light);
    }
    .tag {
      background: var(--bg-alt);
      color: var(--primary);
      font-size: 0.75rem;
      padding: 4px 12px;
      border-radius: 20px;
      display: inline-block;
      margin-top: 10px;
    }
    
    /* 案例对比卡片 */
    .case-grid {
      display: grid;
      grid-template-columns: 1fr 1fr 1fr;
      gap: 24px;
      align-items: start;
    }
    .case-card {
      background: white;
      padding: 28px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      border: 1px solid transparent;
    }
    .case-card.featured {
      border-color: var(--primary-deep);
      transform: scale(1.02);
      box-shadow: var(--shadow-md);
    }
    
    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 18px 0;
      font-weight: 600;
      cursor: pointer;
      color: var(--text-main);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.3s;
      color: var(--text-secondary);
      background: #f9fbfc;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 8px 0 20px;
    }
    
    /* 按钮系统 */
    .btn-primary {
      background: var(--cta);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      display: inline-block;
      transition: background var(--transition);
      border: none;
      cursor: pointer;
    }
    .btn-primary:hover {
      background: var(--cta-hover);
    }
    .btn-outline {
      border: 2px solid var(--primary);
      color: var(--primary);
      padding: 12px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      display: inline-block;
      background: transparent;
      transition: 0.2s;
    }
    .btn-outline:hover {
      background: var(--primary);
      color: white;
    }
    
    /* 页脚 */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 2rem;
      color: var(--footer-text);
    }
    
    @media (max-width: 1024px) {
      .hero-grid { grid-template-columns: 1fr; }
      .hero-left::after { display: none; }
      .advantage-grid { grid-template-columns: repeat(2,1fr); }
      .case-grid { grid-template-columns: 1fr; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .masonry-grid { columns: 1; }
      .footer-grid { grid-template-columns: 1fr 1fr; }
      .hero-grid { padding: 1.5rem 0 2rem; }
      .section-spacing { margin-top: 56px; }
      h1 { font-size: 2rem !important; }
      .stat-block { gap: 1rem; flex-wrap: wrap; }
    }
    @media (max-width: 520px) {
      .advantage-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
      .case-card.featured { transform: none; }
    }