/* roulang page: index */
:root {
      --primary: #0A1F1A;
      --accent-green: #C8F560;
      --milan-red: #E94E3C;
      --white: #FFFFFF;
      --gray-light: #F5F6F8;
      --gray-mid: #6B7280;
      --gray-dark: #1F2937;
      --body-text: #374151;
      --border-light: #E5E7EB;
      --radius-lg: 20px;
      --radius-md: 16px;
      --radius-sm: 12px;
      --radius-btn: 8px;
      --shadow-card: 0 4px 20px rgba(10, 31, 26, 0.06);
      --shadow-hover: 0 12px 32px rgba(10, 31, 26, 0.12);
      --font-title: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --font-body: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
      --font-mono: "DIN Alternate", "SF Mono", "Menlo", monospace;
      --transition-smooth: 0.3s cubic-bezier(0.25, 0.8, 0.25, 1.2);
    }

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

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

    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 32px;
    }

    h1, h2, h3, h4 {
      font-family: var(--font-title);
      font-weight: 700;
    }

    h1 {
      font-size: 56px;
      line-height: 1.1;
      letter-spacing: -0.02em;
      font-weight: 800;
    }

    h2 {
      font-size: 40px;
      line-height: 1.2;
      margin-bottom: 16px;
    }

    h3 {
      font-size: 24px;
      line-height: 1.3;
      font-weight: 600;
      margin-bottom: 12px;
    }

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

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

    button, .btn {
      cursor: pointer;
      font-family: var(--font-body);
      font-weight: 600;
      border: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      transition: var(--transition-smooth);
    }

    /* 导航 */
    .nav-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      height: 72px;
      display: flex;
      align-items: center;
      background: transparent;
      transition: background 0.3s, backdrop-filter 0.3s, box-shadow 0.3s;
    }

    .nav-header.scrolled {
      background: rgba(10, 31, 26, 0.95);
      backdrop-filter: blur(12px);
      box-shadow: 0 4px 20px rgba(0,0,0,0.1);
      border-bottom: 1px solid rgba(200, 245, 96, 0.2);
    }

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

    .logo {
      display: flex;
      align-items: center;
      gap: 10px;
      font-family: var(--font-title);
      font-weight: 700;
      font-size: 22px;
      color: var(--white);
      letter-spacing: -0.3px;
    }

    .logo-icon {
      width: 32px;
      height: 32px;
      background: var(--accent-green);
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--primary);
      font-weight: 800;
      font-size: 18px;
    }

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

    .nav-links a {
      color: rgba(255, 255, 255, 0.85);
      font-weight: 500;
      font-size: 16px;
      transition: color 0.2s;
    }

    .nav-links a:hover {
      color: var(--accent-green);
    }

    .nav-cta {
      background: transparent;
      border: 2px solid var(--white);
      color: var(--white);
      padding: 10px 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: var(--transition-smooth);
    }

    .nav-cta:hover {
      background: var(--white);
      color: var(--primary);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      cursor: pointer;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--white);
      transition: 0.3s;
    }

    /* Hero */
    .hero {
      height: 100vh;
      background: var(--primary);
      display: flex;
      align-items: center;
      position: relative;
      overflow: hidden;
    }

    .hero::before {
      content: "";
      position: absolute;
      top: -20%;
      right: -10%;
      width: 60%;
      height: 120%;
      background: radial-gradient(circle, rgba(200, 245, 96, 0.12) 0%, transparent 70%);
      border-radius: 50%;
    }

    .hero-content {
      position: relative;
      z-index: 2;
      max-width: 700px;
    }

    .hero-tag {
      color: var(--accent-green);
      font-weight: 600;
      font-size: 14px;
      letter-spacing: 0.12em;
      text-transform: uppercase;
      margin-bottom: 20px;
    }

    .hero h1 {
      color: var(--white);
      margin-bottom: 20px;
    }

    .hero-sub {
      font-size: 18px;
      color: rgba(255,255,255,0.8);
      max-width: 560px;
      margin-bottom: 36px;
    }

    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }

    .btn-primary-red {
      background: var(--milan-red);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 700;
      box-shadow: 0 8px 20px rgba(233, 78, 60, 0.3);
    }
    .btn-primary-red:hover {
      background: #C0392B;
      transform: scale(1.03);
    }

    .btn-outline-white {
      background: transparent;
      border: 2px solid white;
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
    }
    .btn-outline-white:hover {
      background: white;
      color: var(--primary);
    }

    /* 通用板块 */
    section {
      padding: 120px 0;
    }

    .section-header {
      text-align: center;
      margin-bottom: 64px;
    }

    .bg-light {
      background: #F9FAFB;
    }

    /* 核心服务 不对称布局 */
    .services-grid {
      display: grid;
      grid-template-columns: 5fr 3.5fr 3.5fr;
      gap: 24px;
    }

    .service-card {
      background: white;
      border-radius: var(--radius-md);
      padding: 32px;
      border: 1px solid var(--border-light);
      box-shadow: var(--shadow-card);
      transition: var(--transition-smooth);
      display: flex;
      flex-direction: column;
    }

    .service-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
      border-color: var(--accent-green);
    }

    .service-card.wide .icon-big {
      width: 64px;
      height: 64px;
      margin-bottom: 20px;
      color: var(--accent-green);
    }

    .service-card:not(.wide) .icon-small {
      width: 40px;
      height: 40px;
      margin-bottom: 16px;
      color: var(--accent-green);
    }

    .tag-core {
      background: var(--accent-green);
      color: var(--primary);
      font-size: 13px;
      font-weight: 700;
      padding: 4px 12px;
      border-radius: 20px;
      align-self: flex-start;
      margin-top: 16px;
    }

    /* 数据 */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      text-align: center;
      border-left: 1px solid var(--border-light);
    }
    .stat-item {
      padding: 40px 16px;
      border-right: 1px solid var(--border-light);
    }
    .stat-number {
      font-family: var(--font-mono);
      font-size: 48px;
      font-weight: 700;
      color: var(--accent-green);
    }
    .stat-label {
      color: var(--gray-mid);
      margin-top: 8px;
    }

    /* 产品展示 交替 */
    .product-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 100px;
    }
    .product-row.reverse {
      flex-direction: row-reverse;
    }
    .product-img {
      flex: 6;
      border-radius: var(--radius-lg);
      overflow: hidden;
      background: linear-gradient(135deg, var(--primary), #1A3A30);
    }
    .product-text {
      flex: 5;
    }
    .feature-list {
      list-style: none;
      margin-top: 20px;
    }
    .feature-list li {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: 14px;
      font-weight: 500;
    }
    .feature-list li::before {
      content: "✓";
      color: var(--accent-green);
      font-weight: bold;
      font-size: 18px;
    }

    /* 时间轴 */
    .timeline {
      position: relative;
      max-width: 800px;
      margin: 0 auto;
      padding-left: 40px;
    }
    .timeline::before {
      content: "";
      position: absolute;
      left: 19px;
      top: 0;
      bottom: 0;
      width: 2px;
      border-left: 2px dashed var(--accent-green);
    }
    .timeline-item {
      display: flex;
      gap: 28px;
      margin-bottom: 48px;
      position: relative;
    }
    .timeline-node {
      width: 40px;
      height: 40px;
      background: var(--accent-green);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      color: var(--primary);
      border: 4px solid var(--primary);
      flex-shrink: 0;
      margin-left: -59px;
    }
    .timeline-card {
      background: white;
      border-radius: var(--radius-sm);
      padding: 24px;
      box-shadow: var(--shadow-card);
      width: 100%;
    }

    /* FAQ */
    .faq-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 20px;
    }
    .faq-item {
      background: white;
      border-radius: var(--radius-sm);
      border: 1px solid var(--border-light);
      padding: 18px 24px;
      cursor: pointer;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      font-weight: 600;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: 0.3s;
      color: #4B5563;
      font-size: 15px;
      margin-top: 0;
    }
    .faq-item.open .faq-answer {
      max-height: 120px;
      margin-top: 16px;
    }

    /* CTA横幅 */
    .cta-band {
      background: var(--primary);
      text-align: center;
      padding: 100px 0;
    }
    .cta-band h2 {
      color: white;
      font-size: 36px;
    }
    .btn-large-red {
      background: var(--milan-red);
      color: white;
      padding: 16px 40px;
      border-radius: var(--radius-btn);
      font-weight: 700;
      font-size: 18px;
      margin-top: 28px;
    }

    /* Footer */
    footer {
      background: var(--gray-dark);
      color: #D1D5DB;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
    }

    @media (max-width: 1024px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .services-grid { grid-template-columns: 1fr 1fr; }
      .timeline { padding-left: 20px; }
      .faq-grid { grid-template-columns: 1fr; }
      .product-row { flex-direction: column; }
      .product-row.reverse { flex-direction: column; }
      h1 { font-size: 44px; }
    }

    @media (max-width: 640px) {
      .container { padding: 0 20px; }
      .services-grid, .stats-grid, .footer-grid { grid-template-columns: 1fr; }
      .hero-buttons .btn { width: 100%; }
      h1 { font-size: 36px; }
      h2 { font-size: 30px; }
      section { padding: 80px 0; }
    }