/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --primary: #4E6EF2;
      --primary-dark: #3B5FDB;
      --primary-light: #EEF1FD;
      --success: #00B578;
      --warning: #FF9F0A;
      --danger: #FA5151;
      --bg: #F5F6FA;
      --white: #FFFFFF;
      --text: #1F2329;
      --text-secondary: #86909C;
      --border-radius: 12px;
      --shadow-sm: 0 2px 12px rgba(0, 0, 0, 0.04);
      --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.08);
      --transition: 150ms ease;
      --font-family: -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
      --max-width: 1200px;
      --header-height: 64px;
      --section-padding: 80px 0;
    }

    /* ----- reset & base ----- */
    *, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
    html { scroll-behavior: smooth; }
    body {
      font-family: var(--font-family);
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.6;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    a { text-decoration: none; color: inherit; }
    img { max-width: 100%; display: block; height: auto; }
    button, input, textarea { font-family: inherit; }
    .container {
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    h1, h2, h3, h4 { font-weight: 600; line-height: 1.3; }
    h1 { font-size: 48px; font-weight: 700; line-height: 1.2; }
    h2 { font-size: 36px; }
    h3 { font-size: 24px; }
    h4 { font-size: 20px; font-weight: 500; }

    /* ----- 按钮 ----- */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      border-radius: 8px;
      font-size: 16px;
      font-weight: 500;
      transition: all 150ms ease;
      cursor: pointer;
      border: none;
      background: transparent;
      white-space: nowrap;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      border: 1px solid var(--primary);
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      filter: brightness(1.05);
    }
    .btn-primary:active {
      transform: scale(0.97);
    }
    .btn-secondary {
      background: transparent;
      color: var(--primary);
      border: 1px solid var(--primary);
    }
    .btn-secondary:hover {
      background: var(--primary-light);
    }
    .btn-ghost {
      background: transparent;
      color: white;
      border: 1px solid white;
    }
    .btn-ghost:hover {
      background: rgba(255,255,255,0.1);
    }
    .btn-large {
      padding: 14px 36px;
      font-size: 18px;
    }

    /* ----- 导航栏 ----- */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--header-height);
      background: rgba(255,255,255,0.85);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      z-index: 1000;
      display: flex;
      align-items: center;
      border-bottom: 1px solid rgba(0,0,0,0.03);
    }
    .header .container {
      display: flex;
      align-items: center;
      justify-content: space-between;
    }
    .logo {
      font-size: 22px;
      font-weight: 700;
      color: var(--text);
      display: flex;
      align-items: center;
      gap: 4px;
    }
    .logo span {
      color: var(--primary);
      font-size: 26px;
      line-height: 1;
    }
    .nav-menu {
      display: flex;
      align-items: center;
      gap: 28px;
    }
    .nav-menu a {
      font-size: 14px;
      color: var(--text-secondary);
      position: relative;
      padding: 4px 0;
      transition: color 0.2s;
    }
    .nav-menu a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--primary);
      transition: width 0.2s ease;
    }
    .nav-menu a:hover { color: var(--primary); }
    .nav-menu a:hover::after { width: 100%; }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: none;
      border: none;
      padding: 8px;
      z-index: 1001;
    }
    .hamburger span {
      display: block;
      width: 24px;
      height: 2px;
      background: var(--text);
      transition: 0.2s;
    }
    .mobile-nav {
      display: none;
    }

    /* ----- Hero ----- */
    .hero {
      padding: calc(var(--header-height) + 40px) 0 60px;
      min-height: 100vh;
      display: flex;
      align-items: center;
      background: linear-gradient(135deg, #f6f8ff 0%, #eef2fc 100%);
      position: relative;
      overflow: hidden;
    }
    .hero .container {
      display: flex;
      align-items: center;
      gap: 48px;
    }
    .hero-left {
      flex: 1 1 60%;
    }
    .hero-left h1 {
      margin-bottom: 20px;
      color: var(--text);
    }
    .hero-left .subtitle {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 32px;
      max-width: 500px;
      line-height: 1.6;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .hero-right {
      flex: 0 0 40%;
      display: flex;
      justify-content: center;
      align-items: center;
      position: relative;
    }
    .star-graphic {
      width: 380px;
      height: 380px;
      background: radial-gradient(circle at 30% 30%, #4E6EF2, #1e3a8a);
      border-radius: 50%;
      position: relative;
      animation: slowRotate 60s linear infinite;
      box-shadow: 0 20px 40px rgba(78,110,242,0.3);
      overflow: hidden;
    }
    .star-graphic::before {
      content: '';
      position: absolute;
      top: 15%;
      left: 15%;
      width: 70%;
      height: 70%;
      border: 2px solid rgba(255,255,255,0.2);
      border-radius: 50%;
    }
    .star-graphic::after {
      content: '';
      position: absolute;
      top: 30%;
      left: 30%;
      width: 40%;
      height: 40%;
      background: rgba(255,255,255,0.08);
      border-radius: 50%;
      filter: blur(10px);
    }
    @keyframes slowRotate {
      from { transform: rotate(0deg); }
      to { transform: rotate(360deg); }
    }
    .hero-right img {
      position: absolute;
      width: 100%;
      height: 100%;
      object-fit: cover;
      border-radius: 50%;
      opacity: 0.6;
      mix-blend-mode: overlay;
    }

    /* ----- 通用 section ----- */
    .section {
      padding: var(--section-padding);
    }
    .section-title {
      text-align: center;
      margin-bottom: 48px;
    }
    .section-title h2 {
      margin-bottom: 12px;
    }
    .section-title p {
      color: var(--text-secondary);
      max-width: 600px;
      margin: 0 auto;
    }

    /* ----- 核心优势 (不对称网格) ----- */
    .advantages-grid {
      display: grid;
      grid-template-columns: 2fr 1fr;
      gap: 24px;
      align-items: stretch;
    }
    .adv-card {
      background: var(--white);
      border-radius: var(--border-radius);
      padding: 28px;
      box-shadow: var(--shadow-sm);
      transition: box-shadow 0.2s, transform 0.2s;
      display: flex;
      flex-direction: column;
    }
    .adv-card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-2px);
    }
    .adv-card-large {
      background: #F0F3FF;
      grid-row: span 2;
    }
    .adv-icon {
      font-size: 32px;
      color: var(--primary);
      margin-bottom: 16px;
    }
    .adv-card h3 {
      margin-bottom: 12px;
    }
    .adv-card p {
      color: var(--text-secondary);
      font-size: 15px;
      line-height: 1.6;
    }
    .adv-stack {
      display: flex;
      flex-direction: column;
      gap: 24px;
    }

    /* ----- 产品矩阵 2x3 网格 ----- */
    .product-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .product-card {
      background: var(--white);
      border-radius: var(--border-radius);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: box-shadow 0.2s, transform 0.2s;
    }
    .product-card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-4px);
    }
    .product-img {
      width: 100%;
      aspect-ratio: 16 / 9;
      overflow: hidden;
    }
    .product-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.3s ease;
    }
    .product-card:hover .product-img img {
      transform: scale(1.03);
    }
    .product-info {
      padding: 20px;
    }
    .product-info h4 {
      margin-bottom: 8px;
    }
    .product-info p {
      color: var(--text-secondary);
      font-size: 14px;
    }

    /* ----- 数据背书深色条 ----- */
    .stats {
      background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
      color: white;
      text-align: center;
      padding: 70px 0;
    }
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 30px;
    }
    .stat-item h3 {
      font-size: 56px;
      font-weight: 700;
      font-family: 'Courier New', monospace;
      margin-bottom: 8px;
    }
    .stat-item p {
      font-size: 16px;
      opacity: 0.9;
    }

    /* ----- 解决方案流程 (时间线) ----- */
    .timeline {
      display: flex;
      flex-direction: column;
      gap: 32px;
      max-width: 800px;
      margin: 0 auto;
      position: relative;
    }
    .timeline::before {
      content: '';
      position: absolute;
      left: 40px;
      top: 0;
      bottom: 0;
      width: 1px;
      background: rgba(0,0,0,0.1);
      border-left: 2px dashed rgba(78,110,242,0.2);
    }
    .timeline-item {
      display: flex;
      gap: 32px;
      align-items: flex-start;
      position: relative;
    }
    .timeline-num {
      font-size: 48px;
      font-weight: 700;
      color: rgba(78,110,242,0.15);
      line-height: 1;
      width: 48px;
      text-align: center;
      flex-shrink: 0;
    }
    .timeline-content h3 {
      margin-bottom: 8px;
    }
    .timeline-content p {
      color: var(--text-secondary);
    }

    /* ----- 案例展示 ----- */
    .case-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .case-card {
      position: relative;
      border-radius: var(--border-radius);
      overflow: hidden;
      background: var(--white);
      box-shadow: var(--shadow-sm);
      transition: transform 0.2s;
    }
    .case-card:hover {
      transform: translateY(-4px);
    }
    .case-img {
      width: 100%;
      aspect-ratio: 4/3;
    }
    .case-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }
    .case-title {
      padding: 16px;
      font-weight: 600;
      font-size: 16px;
    }
    .case-overlay {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: rgba(78,110,242,0);
      display: flex;
      align-items: center;
      justify-content: center;
      transition: background 0.2s;
      pointer-events: none;
    }
    .case-card:hover .case-overlay {
      background: rgba(78,110,242,0.75);
    }
    .case-overlay span {
      color: white;
      font-weight: 500;
      opacity: 0;
      transform: translateY(10px);
      transition: 0.2s;
    }
    .case-card:hover .case-overlay span {
      opacity: 1;
      transform: translateY(0);
    }

    /* ----- FAQ 手风琴----- */
    .faq-wrapper {
      display: grid;
      grid-template-columns: 1fr 2fr;
      gap: 48px;
    }
    .faq-left h2 {
      margin-bottom: 12px;
    }
    .accordion-item {
      border-bottom: 1px solid #e9ebf0;
      padding: 16px 0;
    }
    .accordion-header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      cursor: pointer;
      font-size: 16px;
      background: none;
      border: none;
      width: 100%;
      text-align: left;
      padding: 8px 0;
    }
    .accordion-icon {
      font-size: 20px;
      transition: transform 0.3s ease;
      color: var(--primary);
    }
    .accordion-body {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      color: var(--text-secondary);
      font-size: 15px;
    }
    .accordion-item.active .accordion-body {
      max-height: 200px;
      padding: 12px 0 4px;
    }
    .accordion-item.active .accordion-icon {
      transform: rotate(45deg);
    }

    /* ----- CTA ----- */
    .cta-section {
      background: #F0F3FF;
      text-align: center;
      padding: 80px 0;
    }
    .cta-section h2 {
      margin-bottom: 16px;
    }
    .cta-section p {
      color: var(--text-secondary);
      margin-bottom: 32px;
    }
    .btn-pulse {
      animation: pulse 2s infinite;
    }
    @keyframes pulse {
      0% { box-shadow: 0 0 0 0 rgba(78,110,242,0.4); }
      70% { box-shadow: 0 0 0 15px rgba(78,110,242,0); }
      100% { box-shadow: 0 0 0 0 rgba(78,110,242,0); }
    }

    /* ----- 页脚 ----- */
    .footer {
      background: #1F2329;
      color: var(--text-secondary);
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      margin-bottom: 40px;
    }
    .footer h4 {
      color: white;
      margin-bottom: 16px;
      font-size: 16px;
    }
    .footer a {
      color: var(--text-secondary);
      font-size: 14px;
      display: block;
      margin-bottom: 8px;
      transition: color 0.2s;
    }
    .footer a:hover {
      color: var(--primary);
    }
    .footer-bottom {
      border-top: 1px solid rgba(255,255,255,0.08);
      padding-top: 24px;
      text-align: center;
      font-size: 13px;
    }

    /* ----- 响应式 ----- */
    @media (max-width: 1024px) {
      .advantages-grid {
        grid-template-columns: 1fr;
      }
      .product-grid {
        grid-template-columns: repeat(2, 1fr);
      }
      .case-grid {
        grid-template-columns: repeat(2, 1fr);
      }
      .faq-wrapper {
        grid-template-columns: 1fr;
      }
    }
    @media (max-width: 768px) {
      h1 { font-size: 32px; }
      h2 { font-size: 28px; }
      .container { padding: 0 16px; }
      .section { padding: 60px 0; }
      .hero .container {
        flex-direction: column;
        text-align: center;
      }
      .hero-left, .hero-right {
        flex: unset;
        width: 100%;
      }
      .hero-right {
        margin-top: 30px;
      }
      .star-graphic {
        width: 250px;
        height: 250px;
      }
      .nav-menu {
        display: none;
      }
      .hamburger {
        display: flex;
      }
      .mobile-nav {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 320px;
        height: 100vh;
        background: white;
        box-shadow: -5px 0 20px rgba(0,0,0,0.1);
        display: flex;
        flex-direction: column;
        padding: 80px 30px;
        gap: 32px;
        transition: right 0.3s ease;
        z-index: 999;
      }
      .mobile-nav.active {
        right: 0;
      }
      .mobile-nav a {
        font-size: 18px;
        font-weight: 500;
      }
      .product-grid, .case-grid, .stats-grid {
        grid-template-columns: 1fr;
      }
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }
    @media (max-width: 520px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
      .stats-grid {
        grid-template-columns: 1fr 1fr;
      }
    }