/* roulang page: index */
/* 自定义设计变量与视觉系统 */
    :root {
      --primary: #1E3A5F;
      --primary-deep: #0F172A;
      --accent: #0F766E;
      --accent-hover: #0E5E57;
      --bg-light: #F8FAFC;
      --bg-white: #FFFFFF;
      --text-main: #1E293B;
      --text-muted: #475569;
      --text-light: #94A3B8;
      --border-light: #E2E8F0;
      --shadow-card: 0 4px 20px rgba(0,0,0,0.04);
      --shadow-hover: 0 12px 30px rgba(0,0,0,0.08);
      --radius-lg: 16px;
      --radius-md: 8px;
      --transition-base: 0.3s ease;
    }

    * {
      box-sizing: border-box;
    }

    body {
      font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', system-ui, -apple-system, sans-serif;
      background-color: var(--bg-light);
      color: var(--text-main);
      line-height: 1.6;
      margin: 0;
      -webkit-font-smoothing: antialiased;
    }

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

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

    button, input, textarea {
      font-family: inherit;
      outline: none;
    }

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

    /* 导航 */
    .nav-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 50;
      transition: background 0.3s, box-shadow 0.3s;
      background: transparent;
    }

    .nav-header.scrolled {
      background: rgba(255,255,255,0.95);
      backdrop-filter: blur(8px);
      box-shadow: 0 2px 18px rgba(0,0,0,0.05);
      border-bottom: 1px solid rgba(226,232,240,0.6);
    }

    .nav-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 16px 24px;
      max-width: 1280px;
      margin: 0 auto;
    }

    .logo {
      font-weight: 700;
      font-size: 1.5rem;
      color: var(--primary);
      letter-spacing: -0.3px;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .logo-icon {
      width: 32px;
      height: 32px;
      background: linear-gradient(135deg, var(--primary), var(--accent));
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: white;
      font-weight: 700;
      font-size: 18px;
    }

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

    .nav-link {
      font-weight: 500;
      color: var(--text-main);
      font-size: 0.95rem;
      transition: color 0.2s;
      position: relative;
    }

    .nav-link:hover {
      color: var(--accent);
    }

    .btn-primary {
      background: var(--accent);
      color: white;
      border: none;
      padding: 10px 24px;
      border-radius: var(--radius-md);
      font-weight: 600;
      font-size: 0.9rem;
      cursor: pointer;
      transition: background 0.25s, transform 0.15s;
      display: inline-flex;
      align-items: center;
      gap: 6px;
    }

    .btn-primary:hover {
      background: var(--accent-hover);
      transform: translateY(-1px);
    }

    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      padding: 10px 24px;
      border-radius: var(--radius-md);
      font-weight: 600;
      font-size: 0.9rem;
      cursor: pointer;
      transition: all 0.25s;
    }

    .btn-outline:hover {
      background: rgba(30,58,95,0.05);
      border-color: var(--accent);
      color: var(--accent);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
    }

    .hamburger span {
      width: 24px;
      height: 2.5px;
      background: var(--primary);
      border-radius: 2px;
      transition: 0.3s;
    }

    .mobile-menu {
      position: fixed;
      top: 0;
      right: 0;
      width: 75%;
      max-width: 320px;
      height: 100vh;
      background: white;
      box-shadow: -8px 0 25px rgba(0,0,0,0.08);
      transform: translateX(100%);
      transition: transform 0.4s ease;
      display: flex;
      flex-direction: column;
      padding: 24px;
      z-index: 100;
    }

    .mobile-menu.active {
      transform: translateX(0);
    }

    .mobile-link {
      padding: 14px 0;
      font-weight: 500;
      border-bottom: 1px solid var(--border-light);
    }

    /* Hero */
    .hero-section {
      background: linear-gradient(135deg, #1E3A5F 0%, #0F172A 100%);
      padding: 140px 0 100px;
      color: white;
    }

    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }

    .hero-badge {
      background: rgba(255,255,255,0.12);
      backdrop-filter: blur(4px);
      padding: 6px 16px;
      border-radius: 40px;
      font-size: 0.85rem;
      display: inline-block;
      margin-bottom: 20px;
      color: #E2E8F0;
    }

    h1 {
      font-size: 3rem;
      font-weight: 700;
      line-height: 1.2;
      margin-bottom: 20px;
    }

    .hero-sub {
      font-size: 1.1rem;
      color: #CBD5E1;
      margin-bottom: 32px;
      max-width: 480px;
    }

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

    .hero-image {
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      border-radius: 24px;
      height: 380px;
      box-shadow: 0 25px 50px -12px rgba(0,0,0,0.4);
      border: 1px solid rgba(255,255,255,0.15);
    }

    /* 卡片区域 */
    .section-padding {
      padding: 100px 0;
    }

    .section-title {
      font-size: 2.25rem;
      font-weight: 700;
      margin-bottom: 16px;
    }

    .section-desc {
      color: var(--text-muted);
      font-size: 1.1rem;
      max-width: 640px;
      margin: 0 auto 48px;
      text-align: center;
    }

    .feature-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 32px;
    }

    .feature-card {
      background: white;
      padding: 32px 24px;
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-card);
      transition: var(--transition-base);
    }

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

    .feature-icon {
      width: 56px;
      height: 56px;
      background: rgba(15,118,110,0.1);
      border-radius: 14px;
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 20px;
      color: var(--accent);
      font-size: 24px;
    }

    .dark-block {
      background: #0F172A;
      color: white;
      padding: 90px 0;
    }

    .stat-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 32px;
      text-align: center;
    }

    .stat-number {
      font-size: 2.8rem;
      font-weight: 700;
      color: var(--accent);
    }

    .case-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }

    .case-card {
      border-radius: var(--radius-lg);
      overflow: hidden;
      background: white;
      box-shadow: var(--shadow-card);
      transition: 0.3s;
    }

    .case-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-hover);
    }

    .case-img {
      height: 200px;
      background-size: cover;
      background-position: center;
    }

    .solutions-row {
      display: flex;
      gap: 48px;
      align-items: center;
      margin-bottom: 80px;
    }

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

    .faq-item {
      background: white;
      border-radius: var(--radius-lg);
      padding: 20px 24px;
      margin-bottom: 16px;
      cursor: pointer;
      border: 1px solid var(--border-light);
    }

    .faq-answer {
      display: none;
      margin-top: 12px;
      color: var(--text-muted);
    }

    .faq-item.active .faq-answer {
      display: block;
    }

    .contact-form input, .contact-form textarea {
      width: 100%;
      padding: 14px 16px;
      border: 1px solid #CBD5E1;
      border-radius: var(--radius-md);
      margin-bottom: 16px;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 32px;
      padding: 64px 0 40px;
      color: #CBD5E1;
    }

    @media (max-width: 1024px) {
      .feature-grid, .case-grid { grid-template-columns: repeat(2,1fr); }
      .stat-grid { grid-template-columns: repeat(2,1fr); }
    }

    @media (max-width: 768px) {
      .hamburger { display: flex; }
      .nav-links { display: none; }
      .hero-grid { grid-template-columns: 1fr; }
      h1 { font-size: 2.2rem; }
      .feature-grid, .case-grid { grid-template-columns: 1fr; }
      .solutions-row, .solutions-row.reverse { flex-direction: column; }
      .footer-grid { grid-template-columns: 1fr 1fr; }
      .stat-grid { gap: 24px; }
    }