/* roulang page: index */
:root {
      --primary-deep: #0A1929;
      --accent-cyan: #00E5FF;
      --accent-red: #FF4655;
      --card-bg: #FFFFFF;
      --surface-light: #F8FAFC;
      --text-dark: #1E293B;
      --text-muted: #64748B;
      --border-light: #E2E8F0;
      --white: #FFFFFF;
      --shadow-sm: 0 4px 20px rgba(10, 25, 41, 0.06);
      --shadow-hover: 0 12px 32px rgba(10, 25, 41, 0.12);
      --radius-md: 12px;
      --radius-btn: 8px;
      --transition: 0.3s ease;
      --font-sans: 'Inter', 'SF Pro Text', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'PingFang SC', 'Microsoft YaHei', 'Hiragino Sans GB', sans-serif;
    }

    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--white);
      color: var(--text-dark);
      line-height: 1.8;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }

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

    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.2s;
    }

    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }

    /* 导航 */
    .nav-bar {
      position: sticky;
      top: 0;
      z-index: 50;
      background: var(--white);
      height: 72px;
      display: flex;
      align-items: center;
      box-shadow: 0 1px 0 rgba(0,0,0,0.05);
      backdrop-filter: blur(8px);
      background: rgba(255,255,255,0.92);
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-weight: 700;
      font-size: 24px;
      color: var(--primary-deep);
      display: flex;
      align-items: center;
      gap: 6px;
      letter-spacing: -0.02em;
    }
    .logo i {
      color: var(--accent-cyan);
      font-size: 28px;
    }
    .nav-menu {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-link {
      font-size: 15px;
      font-weight: 500;
      color: #475569;
      position: relative;
      padding: 4px 0;
      transition: color 0.2s;
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-cyan);
      transition: width 0.3s ease;
    }
    .nav-link:hover {
      color: var(--accent-cyan);
    }
    .nav-link:hover::after {
      width: 100%;
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: none;
      border: none;
      padding: 8px;
    }
    .hamburger span {
      display: block;
      width: 24px;
      height: 2px;
      background: var(--primary-deep);
      transition: 0.3s;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 72px;
      left: 0;
      width: 100%;
      background: rgba(10,25,41,0.97);
      backdrop-filter: blur(12px);
      padding: 32px;
      flex-direction: column;
      gap: 24px;
      z-index: 40;
    }
    .mobile-menu a {
      color: white;
      font-size: 20px;
      font-weight: 500;
    }

    /* Hero */
    .hero {
      background: var(--primary-deep);
      min-height: 100vh;
      display: flex;
      align-items: center;
      position: relative;
      overflow: hidden;
    }
    .hero-bg {
      position: absolute;
      inset: 0;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      opacity: 0.25;
      z-index: 0;
    }
    .hero-content {
      position: relative;
      z-index: 2;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 40px;
      flex-wrap: wrap;
    }
    .hero-text {
      flex: 1 1 500px;
    }
    .hero-badge {
      display: inline-block;
      background: var(--accent-cyan);
      color: var(--primary-deep);
      padding: 6px 18px;
      border-radius: 40px;
      font-weight: 600;
      font-size: 14px;
      margin-bottom: 24px;
    }
    .hero h1 {
      font-size: 56px;
      font-weight: 700;
      color: white;
      line-height: 1.2;
      letter-spacing: -0.02em;
      margin-bottom: 20px;
    }
    .hero-sub {
      font-size: 18px;
      color: #94A3B8;
      max-width: 560px;
      margin-bottom: 36px;
    }
    .btn-group {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .btn {
      display: inline-block;
      font-weight: 600;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      transition: background 0.2s, color 0.2s, border 0.2s;
      text-align: center;
      cursor: pointer;
    }
    .btn-primary {
      background: var(--accent-cyan);
      color: var(--primary-deep);
      border: none;
    }
    .btn-primary:hover {
      background: #00B8D4;
    }
    .btn-ghost {
      background: transparent;
      border: 2px solid var(--accent-cyan);
      color: var(--accent-cyan);
    }
    .btn-ghost:hover {
      background: var(--accent-cyan);
      color: var(--primary-deep);
    }
    .hero-image {
      flex: 1 1 400px;
      display: flex;
      justify-content: center;
    }
    .hero-image img {
      max-height: 420px;
      border-radius: 24px;
      box-shadow: 0 20px 40px rgba(0,229,255,0.2);
    }

    /* 区块通用 */
    section {
      padding: 100px 0;
    }
    .section-title {
      font-size: 40px;
      font-weight: 600;
      letter-spacing: -0.02em;
      margin-bottom: 16px;
      color: var(--primary-deep);
    }
    .section-sub {
      color: var(--text-muted);
      max-width: 700px;
      margin-bottom: 48px;
    }

    /* 服务卡片 */
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    .service-card {
      background: var(--card-bg);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 32px;
      box-shadow: var(--shadow-sm);
      transition: all var(--transition);
    }
    .service-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }
    .service-icon {
      font-size: 40px;
      color: var(--accent-cyan);
      margin-bottom: 20px;
    }
    .service-card h3 {
      font-size: 22px;
      font-weight: 600;
      margin-bottom: 12px;
    }

    /* 数据带 */
    .adv-bg {
      background: var(--surface-light);
    }
    .stats-grid {
      display: flex;
      justify-content: space-around;
      text-align: center;
      flex-wrap: wrap;
      gap: 32px;
    }
    .stat-number {
      font-size: 48px;
      font-weight: 700;
      color: var(--accent-cyan);
    }

    /* 案例卡片 */
    .case-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .case-card {
      position: relative;
      border-radius: var(--radius-md);
      overflow: hidden;
      aspect-ratio: 16/9;
      background: #0A1929;
    }
    .case-card img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.4s;
    }
    .case-card:hover img {
      transform: scale(1.05);
    }
    .case-overlay {
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      padding: 24px;
      background: linear-gradient(transparent, rgba(0,0,0,0.8));
      color: white;
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 20px 0;
    }
    .faq-question {
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
      color: var(--text-dark);
    }
    .faq-answer {
      color: #475569;
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      margin-top: 12px;
    }

    /* CTA横幅 */
    .cta-band {
      background: var(--primary-deep);
      text-align: center;
      color: white;
    }

    /* 页脚 */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }

    @media (max-width: 1024px) {
      .grid-4 { grid-template-columns: repeat(2, 1fr); }
      .case-grid { grid-template-columns: repeat(2, 1fr); }
    }
    @media (max-width: 768px) {
      .nav-menu { display: none; }
      .hamburger { display: flex; }
      .hero h1 { font-size: 40px; }
      .grid-4, .case-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
    }