/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --primary-deep: #0A1929;
      --primary-gradient: linear-gradient(135deg, #0A1929 0%, #0D2137 100%);
      --accent-cyan: #00E5FF;
      --accent-glow: rgba(0, 229, 255, 0.6);
      --bg-light: #F5F6FA;
      --bg-footer: #F0F1F5;
      --text-dark: #1F2329;
      --text-muted: #86909C;
      --text-on-dark: #FFFFFF;
      --text-on-dark-secondary: #B0C4DE;
      --card-glass-bg: rgba(255, 255, 255, 0.85);
      --card-border: rgba(255, 255, 255, 0.2);
      --shadow-sm: 0 8px 32px rgba(0,0,0,0.06);
      --shadow-hover: 0 12px 40px rgba(0,0,0,0.1);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-capsule: 24px;
      --font-sans: -apple-system, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --transition-fast: 150ms ease-out;
      --transition-smooth: 250ms ease-out;
      --max-width: 1200px;
      --header-height: 64px;
    }

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

    html {
      scroll-behavior: smooth;
      scroll-padding-top: var(--header-height);
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-light);
      color: var(--text-dark);
      line-height: 1.5;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

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

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

    ul {
      list-style: none;
    }

    .container {
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }

    /* ----- 导航 (固定顶部，玻璃效果) ----- */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--header-height);
      background: rgba(255,255,255,0.9);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      box-shadow: 0 2px 12px rgba(0,0,0,0.04);
      z-index: 1000;
      display: flex;
      align-items: center;
      transition: box-shadow var(--transition-smooth);
      border-bottom: 1px solid rgba(0,0,0,0.02);
    }

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

    .logo {
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--primary-deep);
      letter-spacing: -0.5px;
      display: flex;
      align-items: center;
    }
    .logo i {
      color: var(--accent-cyan);
      margin-right: 8px;
      font-size: 2rem;
    }
    .logo span {
      background: linear-gradient(135deg, #0A1929, #00E5FF);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }

    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
    }
    .nav-links a {
      font-size: 1rem;
      font-weight: 500;
      color: var(--text-dark);
      padding: 0.5rem 0;
      position: relative;
      transition: color var(--transition-fast);
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-cyan);
      transition: width var(--transition-fast);
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary-deep);
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
      padding: 8px;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--primary-deep);
      transition: all var(--transition-fast);
      display: block;
      border-radius: 2px;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: var(--header-height);
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.98);
      backdrop-filter: blur(16px);
      flex-direction: column;
      padding: 2rem;
      gap: 1.5rem;
      box-shadow: 0 20px 30px rgba(0,0,0,0.1);
      z-index: 999;
    }
    .mobile-menu a {
      font-size: 1.2rem;
      font-weight: 500;
    }

    /* ----- 按钮系统 ----- */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 0.75rem 2rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1rem;
      transition: all var(--transition-fast);
      cursor: pointer;
      border: 1px solid transparent;
      text-align: center;
      gap: 0.5rem;
    }
    .btn-primary {
      background: var(--accent-cyan);
      color: var(--primary-deep);
      box-shadow: 0 4px 12px rgba(0,229,255,0.2);
    }
    .btn-primary:hover {
      box-shadow: 0 0 18px var(--accent-glow);
      transform: translateY(-1px);
      background: #00d4ed;
    }
    .btn-secondary {
      background: transparent;
      border-color: var(--accent-cyan);
      color: var(--accent-cyan);
    }
    .btn-secondary:hover {
      background: rgba(0,229,255,0.08);
      border-color: #00d4ed;
      color: #00d4ed;
    }
    .btn-on-dark {
      background: var(--accent-cyan);
      color: var(--primary-deep);
    }
    .btn-on-dark:hover {
      box-shadow: 0 0 24px var(--accent-glow);
    }

    /* ----- 板块通用 ----- */
    section {
      padding: 80px 0;
    }
    .section-title {
      font-size: 2rem;
      font-weight: 700;
      color: var(--primary-deep);
      margin-bottom: 1rem;
      text-align: center;
    }
    .section-sub {
      color: var(--text-muted);
      text-align: center;
      max-width: 700px;
      margin: 0 auto 3rem auto;
      font-size: 1rem;
    }

    /* ----- Hero 首屏 ----- */
    .hero {
      background: var(--primary-gradient);
      padding: 120px 0 100px;
      color: var(--text-on-dark);
      position: relative;
      overflow: hidden;
      margin-top: 0;
    }
    .hero .container {
      display: flex;
      align-items: center;
      gap: 3rem;
    }
    .hero-content {
      flex: 1 1 50%;
    }
    .hero h1 {
      font-size: 2.8rem;
      font-weight: 700;
      line-height: 1.3;
      margin-bottom: 1.5rem;
    }
    .hero h1 span {
      color: var(--accent-cyan);
    }
    .hero p {
      font-size: 1.1rem;
      color: var(--text-on-dark-secondary);
      margin-bottom: 2rem;
      max-width: 500px;
    }
    .hero-buttons {
      display: flex;
      gap: 1rem;
      flex-wrap: wrap;
    }
    .hero-image {
      flex: 1 1 45%;
      position: relative;
    }
    .hero-image img {
      border-radius: var(--radius-card);
      box-shadow: 0 20px 40px rgba(0,0,0,0.3);
      border: 1px solid rgba(255,255,255,0.15);
    }
    .floating-card {
      position: absolute;
      bottom: -20px;
      left: -20px;
      background: var(--card-glass-bg);
      backdrop-filter: blur(12px);
      border: 1px solid var(--card-border);
      border-radius: var(--radius-card);
      padding: 1rem 1.5rem;
      color: var(--text-dark);
      box-shadow: var(--shadow-sm);
    }

    /* 核心优势 1+2 布局 */
    .advantages-grid {
      display: flex;
      gap: 3rem;
      align-items: flex-start;
    }
    .adv-intro {
      flex: 1;
    }
    .adv-intro h2 {
      font-size: 2rem;
      margin-bottom: 1rem;
    }
    .adv-cards {
      flex: 1.2;
      display: flex;
      flex-direction: column;
      gap: 1.5rem;
    }
    .adv-card {
      background: rgba(255,255,255,0.9);
      backdrop-filter: blur(8px);
      border-radius: var(--radius-card);
      padding: 1.8rem;
      box-shadow: var(--shadow-sm);
      display: flex;
      gap: 1.5rem;
      border: 1px solid rgba(0,0,0,0.02);
    }
    .adv-icon {
      font-size: 2rem;
      color: var(--accent-cyan);
    }

    /* 产品功能分组 交错 */
    .feature-row {
      display: flex;
      align-items: center;
      gap: 3rem;
      margin-bottom: 5rem;
    }
    .feature-row.reverse {
      flex-direction: row-reverse;
    }
    .feature-text {
      flex: 1;
    }
    .feature-img {
      flex: 1;
    }
    .feature-img img {
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
    }
    .tags {
      display: flex;
      flex-wrap: wrap;
      gap: 0.75rem;
      margin-top: 1.5rem;
    }
    .tag {
      background: #E8F4FD;
      color: #0A1929;
      padding: 0.3rem 1rem;
      border-radius: 20px;
      font-size: 0.9rem;
      font-weight: 500;
      border: 1px solid rgba(0,229,255,0.3);
    }

    /* 场景卡片网格 */
    .scenes-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 2rem;
    }
    .scene-card {
      background: var(--card-glass-bg);
      backdrop-filter: blur(12px);
      border-radius: var(--radius-card);
      padding: 2rem;
      box-shadow: var(--shadow-sm);
      border: 1px solid rgba(0,0,0,0.02);
    }

    /* 案例卡片 */
    .cases-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 2rem;
    }
    .case-card {
      background: #FFFFFF;
      border-radius: var(--radius-card);
      padding: 2rem;
      box-shadow: var(--shadow-sm);
    }
    .stat-number {
      font-size: 2.2rem;
      font-weight: 700;
      color: var(--accent-cyan);
    }

    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid #E5E8EC;
      padding: 1rem 0;
    }
    .faq-question {
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-muted);
      font-size: 0.95rem;
    }

    /* 最终CTA */
    .cta-dark {
      background: var(--primary-gradient);
      text-align: center;
      padding: 80px 0;
    }

    /* 页脚 */
    .footer {
      background: var(--bg-footer);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 2rem;
    }

    /* 响应式 */
    @media (max-width: 1024px) {
      .hero .container { flex-direction: column; }
      .advantages-grid { flex-direction: column; }
      .feature-row { flex-direction: column; }
      .feature-row.reverse { flex-direction: column; }
      .scenes-grid { grid-template-columns: 1fr; }
      .cases-grid { grid-template-columns: 1fr; }
    }
    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .mobile-menu.active { display: flex; }
      .footer-grid { grid-template-columns: 1fr; }
    }