/* roulang page: index */
/* ----- 全局设计变量 ----- */
    :root {
      --primary: #0B1E2F;
      --accent: #E63946;
      --accent-hover: #C62D38;
      --bg-light: #F8F9FA;
      --card-bg: #FFFFFF;
      --text-main: #1A1A1A;
      --text-secondary: #5A5A5A;
      --text-muted: #8A8A8A;
      --text-on-dark: #FFFFFF;
      --text-on-dark-muted: #B0BEC5;
      --border-light: #E5E5E5;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --shadow-card: 0 2px 12px rgba(0,0,0,0.04);
      --shadow-card-hover: 0 8px 30px rgba(0,0,0,0.08);
      --shadow-nav: 0 2px 20px rgba(0,0,0,0.06);
      --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
      --font-number: "DIN Alternate", "Bebas Neue", "PingFang SC", sans-serif;
      --max-width: 1280px;
      --section-gap: 100px;
      --card-padding: 32px;
      --transition-fast: 0.25s ease;
      --transition-smooth: 0.3s ease;
    }

    /* ----- 全局重置与基础样式 ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    html {
      scroll-behavior: smooth;
      scroll-padding-top: 80px;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-light);
      color: var(--text-main);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }

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

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

    ul {
      list-style: none;
    }

    button, .btn {
      cursor: pointer;
      font-family: inherit;
    }

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

    /* ----- 导航系统（固定顶部，白底变体） ----- */
    #header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      background: transparent;
      transition: background var(--transition-smooth), box-shadow var(--transition-smooth);
      padding: 16px 0;
    }

    #header.scrolled {
      background: rgba(255,255,255,0.98);
      backdrop-filter: blur(8px);
      box-shadow: var(--shadow-nav);
    }

    #header .container {
      display: flex;
      align-items: center;
      justify-content: space-between;
    }

    .logo {
      font-size: 24px;
      font-weight: 700;
      color: var(--text-on-dark);
      letter-spacing: -0.3px;
      transition: color var(--transition-smooth);
      white-space: nowrap;
    }

    #header.scrolled .logo {
      color: var(--primary);
    }

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

    .nav-menu a {
      font-size: 16px;
      font-weight: 500;
      color: var(--text-on-dark-muted);
      position: relative;
      padding: 8px 0;
      transition: color var(--transition-fast);
    }

    #header.scrolled .nav-menu a {
      color: var(--text-secondary);
    }

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

    .nav-menu a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent);
      transition: width var(--transition-fast);
    }

    .nav-menu a:hover::after,
    .nav-menu a.active::after {
      width: 100%;
    }

    .btn-primary-nav {
      background: var(--accent);
      color: white !important;
      padding: 10px 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: background var(--transition-fast), box-shadow var(--transition-fast);
      border: none;
    }

    .btn-primary-nav:hover {
      background: var(--accent-hover);
      box-shadow: 0 4px 12px rgba(230,57,70,0.3);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: none;
      border: none;
      padding: 4px;
      z-index: 1100;
    }

    .hamburger span {
      display: block;
      width: 24px;
      height: 2px;
      background: var(--text-on-dark);
      transition: var(--transition-fast);
    }

    #header.scrolled .hamburger span {
      background: var(--primary);
    }

    /* 移动端覆盖菜单 */
    .mobile-overlay {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: rgba(11,30,47,0.97);
      backdrop-filter: blur(12px);
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 40px;
      z-index: 1050;
      opacity: 0;
      visibility: hidden;
      transition: opacity var(--transition-smooth), visibility var(--transition-smooth);
    }

    .mobile-overlay.active {
      opacity: 1;
      visibility: visible;
    }

    .mobile-overlay a {
      font-size: 24px;
      color: white;
      font-weight: 500;
    }

    .mobile-overlay .btn-primary-nav {
      font-size: 18px;
      padding: 14px 32px;
    }

    /* ----- Hero 首屏（深色数据粒子背景） ----- */
    #hero {
      background: var(--primary);
      min-height: 100vh;
      display: flex;
      align-items: center;
      position: relative;
      overflow: hidden;
      padding: 120px 0 80px;
    }

    .particles {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      pointer-events: none;
    }

    .particle {
      position: absolute;
      background: rgba(255,255,255,0.12);
      border-radius: 50%;
      animation: float 14s infinite ease-in-out;
    }

    @keyframes float {
      0%, 100% { transform: translateY(0) scale(0.8); opacity: 0.1; }
      50% { transform: translateY(-30px) scale(1.1); opacity: 0.25; }
    }

    .hero-content {
      position: relative;
      z-index: 10;
      text-align: center;
      max-width: 800px;
      margin: 0 auto;
      color: white;
    }

    .hero-content h1 {
      font-size: 48px;
      font-weight: 700;
      line-height: 1.2;
      letter-spacing: -0.5px;
      margin-bottom: 24px;
    }

    .hero-content .subtitle {
      font-size: 18px;
      color: var(--text-on-dark-muted);
      margin-bottom: 48px;
      line-height: 1.6;
    }

    .hero-buttons {
      display: flex;
      gap: 20px;
      justify-content: center;
      flex-wrap: wrap;
    }

    .btn-main {
      background: var(--accent);
      color: white;
      padding: 14px 36px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
      letter-spacing: 0.5px;
      transition: background var(--transition-fast), box-shadow var(--transition-fast);
      display: inline-block;
    }

    .btn-main:hover {
      background: var(--accent-hover);
      box-shadow: 0 8px 20px rgba(230,57,70,0.4);
    }

    .btn-outline-light {
      background: transparent;
      color: white;
      padding: 14px 36px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
      border: 1.5px solid white;
      transition: all var(--transition-fast);
    }

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

    /* 通用板块样式 */
    section {
      padding: var(--section-gap) 0;
    }

    .section-title {
      font-size: 36px;
      font-weight: 600;
      letter-spacing: -0.3px;
      margin-bottom: 16px;
      color: var(--text-main);
      text-align: center;
    }

    .section-subtitle {
      color: var(--text-secondary);
      text-align: center;
      margin-bottom: 60px;
      font-size: 18px;
    }

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

    .grid-4 {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }

    .card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      padding: var(--card-padding);
      box-shadow: var(--shadow-card);
      transition: transform var(--transition-fast), box-shadow var(--transition-fast);
    }

    .card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-card-hover);
    }

    .icon-accent {
      color: var(--accent);
      font-size: 32px;
      margin-bottom: 20px;
    }

    /* 服务矩阵左右交替 */
    .service-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 80px;
    }

    .service-row.reverse {
      flex-direction: row-reverse;
    }

    .service-text {
      flex: 1;
    }

    .service-text h3 {
      font-size: 28px;
      margin-bottom: 16px;
    }

    .service-text ul li {
      margin-bottom: 10px;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .service-text ul li i {
      color: var(--accent);
      font-size: 12px;
    }

    .service-img {
      flex: 1;
      background: #E8ECF0;
      border-radius: var(--radius-card);
      height: 360px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--text-muted);
      font-size: 14px;
    }

    .link-cta {
      color: var(--accent);
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      gap: 6px;
      margin-top: 20px;
      transition: gap var(--transition-fast);
    }

    .link-cta:hover {
      gap: 12px;
      text-decoration: underline;
    }

    /* 数据数字 */
    .stat-number {
      font-family: var(--font-number);
      font-size: 42px;
      font-weight: 700;
      color: var(--accent);
    }

    /* 方案卡片配图 */
    .solution-img {
      background: #E8ECF0;
      height: 180px;
      border-radius: 12px;
      margin-bottom: 24px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--text-muted);
    }

    /* FAQ */
    .faq-item {
      border-left: 3px solid rgba(230,57,70,0.3);
      padding-left: 24px;
      margin-bottom: 20px;
      transition: border-color var(--transition-fast);
    }
    .faq-item.active {
      border-left-color: var(--accent);
    }
    .faq-question {
      font-weight: 600;
      font-size: 20px;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: var(--text-secondary);
    }

    /* CTA 深色区 */
    #cta {
      background: var(--primary);
      color: white;
    }

    /* 页脚 */
    footer {
      background: var(--primary);
      color: var(--text-on-dark-muted);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 30px;
    }

    @media (max-width: 1024px) {
      .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); }
      .service-row { flex-direction: column; gap: 30px; }
      .service-row.reverse { flex-direction: column; }
    }

    @media (max-width: 768px) {
      .nav-menu { display: none; }
      .hamburger { display: flex; }
      .grid-3, .grid-4 { grid-template-columns: 1fr; }
      .hero-content h1 { font-size: 32px; }
      .section-title { font-size: 28px; }
    }