/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --primary: #1E2A38;
      --primary-hover: #2C3B4F;
      --accent: #F15A24;
      --accent-hover: #E04A1A;
      --bg: #F7F8FA;
      --bg-card: #FFFFFF;
      --text-primary: #1A1A1A;
      --text-secondary: #5A5F66;
      --text-muted: #8E9399;
      --success: #1F7B4D;
      --border-light: #E0E3E8;
      --radius-card: 12px;
      --radius-btn: 8px;
      --shadow-sm: 0 2px 12px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
      --shadow-hover: 0 8px 24px rgba(0,0,0,0.08);
      --font-title: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --font-body: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --transition: 0.2s ease;
      --nav-height: 64px;
    }

    /* ----- 基础重置 ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    html {
      scroll-behavior: smooth;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

    body {
      font-family: var(--font-body);
      font-size: 16px;
      font-weight: 400;
      line-height: 1.7;
      color: var(--text-primary);
      background-color: var(--bg);
      min-height: 100vh;
    }

    img {
      max-width: 100%;
      height: auto;
      display: block;
    }

    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }

    ul, ol {
      list-style: none;
    }

    button, input {
      font-family: inherit;
      font-size: inherit;
      border: none;
      outline: none;
    }

    /* ----- 容器 ----- */
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 20px;
    }

    /* ----- 导航 (sticky 白底平台) ----- */
    .nav-header {
      position: sticky;
      top: 0;
      width: 100%;
      height: var(--nav-height);
      background: #FFFFFF;
      box-shadow: 0 1px 6px rgba(0,0,0,0.04);
      z-index: 100;
      display: flex;
      align-items: center;
    }

    .nav-inner {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }

    .logo {
      font-size: 22px;
      font-weight: 700;
      font-family: var(--font-title);
      color: var(--primary);
      letter-spacing: 1px;
      line-height: 1;
    }

    .nav-menu {
      display: flex;
      gap: 32px;
      align-items: center;
    }

    .nav-link {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-secondary);
      position: relative;
      padding: 4px 0;
      transition: color var(--transition);
    }

    .nav-link:hover,
    .nav-link.active {
      color: var(--accent);
    }

    /* 移动端汉堡按钮 */
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      padding: 8px 0;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--primary);
      transition: all var(--transition);
      display: block;
    }

    /* 移动端导航面板 */
    .mobile-nav {
      display: none;
      position: fixed;
      top: var(--nav-height);
      left: 0;
      width: 100%;
      background: var(--primary);
      padding: 24px 0;
      flex-direction: column;
      gap: 20px;
      align-items: center;
      z-index: 99;
      box-shadow: 0 10px 20px rgba(0,0,0,0.15);
    }

    .mobile-nav a {
      color: #FFFFFF;
      font-size: 18px;
      font-weight: 500;
    }
    .mobile-nav a:hover {
      color: var(--accent);
    }

    /* ----- 按钮系统 ----- */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
      transition: background var(--transition), color var(--transition), border var(--transition), transform var(--transition);
      cursor: pointer;
      text-align: center;
      border: 1.5px solid transparent;
    }

    .btn-primary {
      background: var(--primary);
      color: white;
      border-color: var(--primary);
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      border-color: var(--primary-hover);
    }

    .btn-accent {
      background: var(--accent);
      color: white;
      border-color: var(--accent);
    }
    .btn-accent:hover {
      background: var(--accent-hover);
      border-color: var(--accent-hover);
    }

    .btn-ghost {
      background: transparent;
      color: var(--primary);
      border: 1.5px solid var(--primary);
    }
    .btn-ghost:hover {
      background: var(--primary);
      color: white;
    }

    /* ----- 区块间距 ----- */
    section {
      padding: 80px 0;
    }

    /* ----- 首屏 Hero ----- */
    .hero {
      background: linear-gradient(135deg, #F7F8FA 0%, #E8EBF0 100%);
      padding: 70px 0 80px;
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 48px;
    }
    .hero-text {
      flex: 1;
    }
    .hero-text h1 {
      font-size: 40px;
      font-weight: 700;
      line-height: 1.2;
      color: var(--primary);
      margin-bottom: 20px;
    }
    .hero-text .subtitle {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 32px;
      max-width: 540px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
      margin-bottom: 24px;
    }
    .trust-note {
      font-size: 13px;
      color: var(--text-muted);
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .hero-image {
      flex: 1;
      border-radius: 16px;
      overflow: hidden;
      box-shadow: var(--shadow-sm);
    }
    .hero-image img {
      width: 100%;
      height: auto;
      object-fit: cover;
    }

    /* ----- 区块标题 ----- */
    .section-title {
      text-align: center;
      margin-bottom: 48px;
    }
    .section-title h2 {
      font-size: 28px;
      font-weight: 600;
      color: var(--primary);
      margin-bottom: 12px;
    }
    .section-title .subhead {
      font-size: 16px;
      color: var(--text-secondary);
      max-width: 600px;
      margin: 0 auto;
    }

    /* 卡片网格 */
    .card-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }

    .feature-card {
      background: var(--bg-card);
      padding: 32px 24px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      transition: all var(--transition);
      text-align: center;
    }
    .feature-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
      border: 1px solid var(--accent);
    }
    .icon-wrap {
      margin-bottom: 20px;
      color: var(--accent);
    }
    .feature-card h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 12px;
    }
    .feature-card p {
      color: var(--text-secondary);
      font-size: 15px;
      line-height: 1.6;
    }

    /* 场景两列卡片 */
    .scenario-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 24px;
    }
    .scenario-card {
      background: var(--bg-card);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      overflow: hidden;
      display: flex;
      flex-direction: column;
    }
    .scenario-img {
      height: 200px;
      overflow: hidden;
    }
    .scenario-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }
    .scenario-content {
      padding: 24px;
    }
    .scenario-content h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 10px;
    }
    .scenario-content p {
      color: var(--text-secondary);
    }

    /* 数据卡片 */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      text-align: center;
    }
    .stat-item {
      background: var(--bg-card);
      padding: 32px 16px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
    }
    .stat-number {
      font-size: 36px;
      font-weight: 700;
      color: var(--success);
      line-height: 1.2;
      margin-bottom: 8px;
    }
    .stat-label {
      color: var(--text-secondary);
    }

    /* FAQ 手风琴 */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
      display: flex;
      flex-direction: column;
      gap: 12px;
    }
    .faq-item {
      background: var(--bg-card);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      overflow: hidden;
    }
    .faq-question {
      width: 100%;
      background: transparent;
      padding: 20px 24px;
      font-size: 16px;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      color: var(--text-primary);
    }
    .faq-icon {
      color: var(--accent);
      font-size: 20px;
      font-weight: bold;
      transition: transform 0.2s;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      background: #F7F8FA;
      padding: 0 24px;
      color: var(--text-secondary);
      font-size: 15px;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 16px 24px;
    }

    /* CTA 区块 */
    .cta-section {
      background: var(--primary);
      color: white;
      text-align: center;
      padding: 70px 20px;
    }
    .cta-section h2 {
      font-size: 28px;
      font-weight: 600;
      margin-bottom: 16px;
    }
    .cta-section p {
      color: rgba(255,255,255,0.8);
      margin-bottom: 32px;
    }
    .cta-disclaimer {
      margin-top: 20px;
      font-size: 13px;
      color: var(--text-muted);
    }

    /* 页脚 */
    .footer {
      background: #1A1A1A;
      color: var(--text-muted);
      padding: 40px 20px;
      font-size: 14px;
    }
    .footer-grid {
      display: flex;
      justify-content: space-between;
      align-items: flex-start;
      flex-wrap: wrap;
      gap: 24px;
    }
    .footer-links a {
      color: var(--text-muted);
      margin-right: 24px;
    }
    .footer-links a:hover {
      color: var(--accent);
    }

    /* ----- 响应式 ----- */
    @media (max-width: 1024px) {
      .card-grid { grid-template-columns: repeat(2, 1fr); }
    }

    @media (max-width: 768px) {
      .nav-menu { display: none; }
      .hamburger { display: flex; }
      .hero-grid {
        flex-direction: column;
        text-align: center;
      }
      .hero-text h1 { font-size: 32px; }
      .card-grid { grid-template-columns: 1fr; }
      .scenario-grid { grid-template-columns: 1fr; }
      .stats-grid { grid-template-columns: 1fr; }
      section { padding: 48px 0; }
      .footer-grid { flex-direction: column; align-items: flex-start; }
      .btn { width: 100%; justify-content: center; }
    }

    @media (max-width: 480px) {
      .hero-text h1 { font-size: 28px; }
    }