/* roulang page: index */
/* ----- 设计变量与全局重置 ----- */
    :root {
      --deep-space: #0A0E17;
      --dark-panel: #141A26;
      --card-bg: #1A2030;
      --electric-purple: #8B5CF6;
      --electric-purple-hover: #7C3AED;
      --cyber-cyan: #06D6A0;
      --text-primary: #E2E8F0;
      --text-secondary: #94A3B8;
      --border-subtle: rgba(255, 255, 255, 0.06);
      --border-active: rgba(139, 92, 246, 0.3);
      --shadow-card: 0 20px 40px rgba(139, 92, 246, 0.08);
      --radius-md: 8px;
      --radius-lg: 16px;
      --transition-smooth: 0.3s ease;
      --container-max: 1280px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", Inter, sans-serif;
      background-color: var(--deep-space);
      color: var(--text-primary);
      line-height: 1.5;
      -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;
      border: none;
      background: none;
    }
    /* 容器 */
    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }
    /* 板块通用间距 */
    section {
      padding: 100px 0;
    }
    @media (max-width: 768px) {
      section {
        padding: 60px 0;
      }
    }
    /* ----- 导航栏 ----- */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      background: rgba(10, 14, 23, 0.85);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-subtle);
      transition: background var(--transition-smooth);
    }
    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .logo {
      font-size: 1.8rem;
      font-weight: 800;
      letter-spacing: -0.5px;
      color: #fff;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo i {
      color: var(--electric-purple);
      font-size: 2rem;
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-secondary);
      position: relative;
      padding: 8px 0;
      transition: color var(--transition-smooth);
    }
    .nav-links a::after {
      content: "";
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--electric-purple);
      transition: width var(--transition-smooth);
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--electric-purple);
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }
    .menu-toggle {
      display: none;
      font-size: 1.8rem;
      color: #fff;
      background: none;
      border: none;
    }
    @media (max-width: 768px) {
      .nav-links {
        position: fixed;
        top: 72px;
        left: 0;
        width: 100%;
        height: calc(100vh - 72px);
        background: var(--deep-space);
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 40px;
        transform: translateX(100%);
        transition: transform 0.4s ease;
        font-size: 1.5rem;
      }
      .nav-links.open {
        transform: translateX(0);
      }
      .menu-toggle {
        display: block;
      }
    }
    /* ----- 按钮系统 ----- */
    .btn-primary {
      background: var(--electric-purple);
      color: #fff;
      padding: 14px 32px;
      border-radius: var(--radius-md);
      font-weight: 700;
      letter-spacing: 0.05em;
      transition: background var(--transition-smooth), box-shadow var(--transition-smooth);
    }
    .btn-primary:hover {
      background: var(--electric-purple-hover);
      box-shadow: 0 0 20px rgba(139, 92, 246, 0.4);
    }
    .btn-secondary {
      background: transparent;
      border: 1px solid rgba(255,255,255,0.2);
      color: #fff;
      padding: 14px 32px;
      border-radius: var(--radius-md);
      font-weight: 700;
      transition: border-color var(--transition-smooth), color var(--transition-smooth);
    }
    .btn-secondary:hover {
      border-color: var(--electric-purple);
      color: var(--electric-purple);
    }
    .btn-large {
      padding: 18px 48px;
      font-size: 1.1rem;
    }
    /* ----- 卡片组件 ----- */
    .card {
      background: var(--card-bg);
      border: 1px solid var(--border-subtle);
      border-radius: var(--radius-lg);
      padding: 32px;
      transition: transform var(--transition-smooth), border-color var(--transition-smooth), box-shadow var(--transition-smooth);
    }
    .card:hover {
      transform: translateY(-4px);
      border-color: var(--border-active);
      box-shadow: var(--shadow-card);
    }
    /* ----- 首屏 Hero ----- */
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
    }
    .hero-title {
      font-size: 56px;
      font-weight: 800;
      line-height: 1.1;
      letter-spacing: -0.02em;
      color: #fff;
      margin-bottom: 24px;
    }
    .hero-sub {
      font-size: 1.2rem;
      color: var(--text-secondary);
      margin-bottom: 40px;
      max-width: 90%;
    }
    .hero-actions {
      display: flex;
      gap: 24px;
      flex-wrap: wrap;
    }
    .hero-visual {
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      min-height: 400px;
      border-radius: var(--radius-lg);
      position: relative;
      overflow: hidden;
      box-shadow: 0 0 40px rgba(139,92,246,0.15);
    }
    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
        text-align: center;
      }
      .hero-title {
        font-size: 36px;
      }
      .hero-sub {
        max-width: 100%;
      }
      .hero-actions {
        justify-content: center;
      }
      .hero-visual {
        min-height: 280px;
        order: -1;
      }
    }
    /* 通用区块标题 */
    .section-title {
      font-size: 40px;
      font-weight: 700;
      letter-spacing: -0.01em;
      margin-bottom: 16px;
      color: #fff;
    }
    .section-sub {
      color: var(--text-secondary);
      margin-bottom: 48px;
    }
    /* 痛点网格 */
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    /* 解决方案交替布局 */
    .solution-row {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
      margin-bottom: 80px;
    }
    .solution-img {
      background: #1A2030;
      border-radius: var(--radius-lg);
      min-height: 300px;
      display: flex;
      align-items: center;
      justify-content: center;
      overflow: hidden;
    }
    /* 服务卡片网格 */
    .services-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .service-card {
      position: relative;
      border-top: 3px solid transparent;
      transition: border-color var(--transition-smooth);
    }
    .service-card:hover {
      border-top-color: var(--electric-purple);
    }
    /* 数据墙 */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 32px;
      text-align: center;
    }
    .stat-number {
      font-family: Inter, sans-serif;
      font-weight: 800;
      font-size: 3rem;
      color: var(--cyber-cyan);
    }
    /* 证言卡片 */
    .testimonial-card {
      background: var(--card-bg);
      border-left: 3px solid var(--electric-purple);
      padding: 28px;
      border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
    }
    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border-subtle);
      padding: 24px 0;
      cursor: pointer;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      font-weight: 600;
      font-size: 1.2rem;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: var(--text-secondary);
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      margin-top: 16px;
    }
    /* CTA 区块 */
    .cta-block {
      background: #0A0E17;
      position: relative;
      text-align: center;
      padding: 100px 0;
      border-top: 1px solid var(--border-subtle);
    }
    /* 页脚 */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      padding: 60px 0;
    }
    @media (max-width: 768px) {
      .grid-3, .services-grid, .stats-grid, .footer-grid {
        grid-template-columns: 1fr;
      }
      .stats-grid {
        grid-template-columns: 1fr 1fr;
      }
      .solution-row {
        grid-template-columns: 1fr;
      }
      .section-title {
        font-size: 28px;
      }
    }
    .text-secondary {
      color: var(--text-secondary);
    }
    .mb-24 { margin-bottom: 24px; }
    .mt-16 { margin-top: 16px; }