/* roulang page: index */
:root {
      --primary: #1A5F7A;
      --primary-dark: #14506B;
      --secondary: #0D9488;
      --secondary-hover: #0F766E;
      --accent: #F59E0B;
      --bg: #F8FAFC;
      --card-bg: #FFFFFF;
      --text-primary: #0F172A;
      --text-body: #334155;
      --text-muted: #64748B;
      --border: #E2E8F0;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
      --shadow-md: 0 10px 25px rgba(0,0,0,0.08), 0 4px 10px rgba(0,0,0,0.04);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-tag: 6px;
      --max-width: 1200px;
      --nav-height: 72px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
      background-color: var(--bg);
      color: var(--text-body);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    /* 导航 */
    .nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      z-index: 1000;
      display: flex;
      align-items: center;
      background: transparent;
      transition: background 0.3s, box-shadow 0.3s;
    }
    .nav.scrolled {
      background: #FFFFFF;
      box-shadow: 0 4px 20px rgba(0,0,0,0.04);
    }
    .nav .container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo {
      font-size: 22px;
      font-weight: 700;
      color: #FFFFFF;
      letter-spacing: 0.5px;
      text-decoration: none;
      display: flex;
      align-items: center;
      gap: 6px;
      transition: color 0.3s;
    }
    .nav.scrolled .logo {
      color: var(--primary);
    }
    .logo-icon {
      font-size: 26px;
      line-height: 1;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    .nav-links a {
      text-decoration: none;
      font-weight: 500;
      font-size: 15px;
      color: rgba(255,255,255,0.9);
      transition: color 0.2s;
    }
    .nav.scrolled .nav-links a {
      color: var(--text-body);
    }
    .nav-links a:hover {
      color: var(--secondary);
    }
    .nav-cta {
      background: var(--secondary);
      color: #FFFFFF !important;
      padding: 10px 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: background 0.2s, transform 0.15s;
    }
    .nav-cta:hover {
      background: var(--secondary-hover);
      transform: scale(0.97);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: #FFFFFF;
      transition: 0.3s;
    }
    .nav.scrolled .hamburger span {
      background: var(--primary);
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: #FFFFFF;
      z-index: 999;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 32px;
    }
    .mobile-menu.active {
      display: flex;
    }
    .mobile-menu a {
      font-size: 20px;
      color: var(--text-primary);
      text-decoration: none;
      font-weight: 600;
    }
    /* Hero */
    .hero {
      background-color: var(--bg);
      padding: 160px 0 100px;
      position: relative;
      overflow: hidden;
    }
    .hero .container {
      display: flex;
      align-items: center;
      gap: 60px;
    }
    .hero-content {
      flex: 1;
    }
    .hero h1 {
      font-size: 48px;
      line-height: 1.2;
      font-weight: 700;
      color: var(--text-primary);
      margin-bottom: 20px;
      letter-spacing: -0.5px;
    }
    .hero-sub {
      font-size: 18px;
      color: var(--text-muted);
      margin-bottom: 32px;
      max-width: 500px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
      margin-bottom: 32px;
    }
    .btn {
      display: inline-block;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
      text-decoration: none;
      transition: background 0.2s, transform 0.15s, box-shadow 0.2s;
      cursor: pointer;
    }
    .btn-primary {
      background: var(--secondary);
      color: #fff;
    }
    .btn-primary:hover {
      background: var(--secondary-hover);
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
    }
    .btn-outline:hover {
      background: #F1F5F9;
    }
    .trust-badges {
      display: flex;
      gap: 24px;
      color: var(--text-muted);
      font-size: 14px;
    }
    .hero-image {
      flex: 1;
      text-align: right;
    }
    .hero-image img {
      max-width: 100%;
      height: auto;
      border-radius: 24px;
    }
    /* 通用区块 */
    section {
      padding: 100px 0;
    }
    .section-title {
      text-align: center;
      margin-bottom: 60px;
    }
    .section-title h2 {
      font-size: 36px;
      font-weight: 600;
      color: var(--text-primary);
    }
    .section-title p {
      color: var(--text-muted);
      font-size: 18px;
      margin-top: 12px;
    }
    /* 优势卡片 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    .feature-card {
      background: var(--card-bg);
      padding: 32px;
      border-radius: var(--radius-card);
      border: 1px solid var(--border);
      box-shadow: var(--shadow-sm);
      transition: transform 0.25s, box-shadow 0.25s;
    }
    .feature-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }
    .feature-icon {
      width: 56px;
      height: 56px;
      background: #E6F0F5;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 20px;
      color: var(--secondary);
      font-size: 24px;
    }
    .feature-card h3 {
      font-size: 20px;
      font-weight: 600;
      color: var(--text-primary);
      margin-bottom: 10px;
    }
    /* 功能分组 */
    .feature-group {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 80px;
    }
    .feature-group.reverse {
      flex-direction: row-reverse;
    }
    .feature-text {
      flex: 1;
    }
    .feature-text h2 {
      font-size: 32px;
      font-weight: 600;
      color: var(--text-primary);
      margin-bottom: 20px;
    }
    .feature-list {
      list-style: none;
      margin-bottom: 24px;
    }
    .feature-list li {
      margin-bottom: 12px;
      display: flex;
      align-items: center;
      gap: 10px;
    }
    .feature-image {
      flex: 1;
    }
    .feature-image img {
      width: 100%;
      border-radius: 16px;
    }
    /* 场景卡片 */
    .scenes-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .scene-card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      overflow: hidden;
      border: 1px solid var(--border);
      transition: transform 0.2s;
    }
    .scene-card:hover {
      transform: translateY(-4px);
    }
    .scene-card img {
      width: 100%;
      height: 180px;
      object-fit: cover;
    }
    .scene-content {
      padding: 24px;
    }
    /* 案例区 */
    .cases {
      background: #F1F5F9;
    }
    .stats-grid {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      gap: 30px;
      margin-bottom: 40px;
    }
    .stat-item {
      text-align: center;
    }
    .stat-number {
      font-family: "Inter", "Segoe UI", sans-serif;
      font-size: 40px;
      font-weight: 700;
      color: var(--secondary);
      line-height: 1.2;
    }
    .brand-logos {
      display: flex;
      justify-content: center;
      gap: 40px;
      flex-wrap: wrap;
      filter: grayscale(100%);
      opacity: 0.7;
    }
    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      border-bottom: 1px solid var(--border);
    }
    .faq-question {
      width: 100%;
      background: var(--card-bg);
      border: none;
      padding: 20px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 18px;
      font-weight: 600;
      color: var(--text-primary);
      cursor: pointer;
      transition: background 0.2s;
    }
    .faq-question:hover {
      background: #F0F9FF;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: #F8FAFC;
      padding: 0 20px;
    }
    .faq-answer.open {
      max-height: 200px;
      padding: 20px;
    }
    /* CTA */
    .cta-section {
      background: var(--primary);
      text-align: center;
      padding: 80px 0;
      color: #FFFFFF;
    }
    .cta-section h2 {
      font-size: 36px;
      color: white;
      margin-bottom: 16px;
    }
    .btn-white {
      background: white;
      color: var(--primary);
      padding: 16px 40px;
    }
    /* 页脚 */
    footer {
      background: #0F172A;
      color: #CBD5E1;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }
    @media (max-width: 1024px) {
      .hero .container { flex-direction: column; }
      .features-grid { grid-template-columns: repeat(2, 1fr); }
      .feature-group { flex-direction: column; }
      .scenes-grid { grid-template-columns: repeat(2, 1fr); }
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }
    @media (max-width: 640px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .hero h1 { font-size: 32px; }
      .features-grid, .scenes-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
    }