/* roulang page: index */
/* 全局设计变量与重置 */
    :root {
      --primary: #1A5F7A;
      --primary-dark: #124B61;
      --accent: #FF6B35;
      --accent-dark: #E55A2B;
      --bg-light: #F8F9FA;
      --white: #FFFFFF;
      --text-heading: #0B1E2E;
      --text-body: #4A5B6B;
      --text-muted: #8E9BAE;
      --border-light: #E9ECEF;
      --shadow-sm: 0 4px 12px rgba(26,95,122,0.04);
      --shadow-md: 0 12px 24px rgba(26,95,122,0.08);
      --shadow-lg: 0 20px 32px rgba(26,95,122,0.12);
      --radius-sm: 8px;
      --radius-pill: 40px;
      --transition: 0.25s ease-in-out;
      --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    }
    * {
      box-sizing: border-box;
    }
    body {
      font-family: var(--font-stack);
      background-color: var(--bg-light);
      color: var(--text-body);
      line-height: 1.7;
      margin: 0;
      font-weight: 400;
      -webkit-font-smoothing: antialiased;
    }
    h1, h2, h3, h4 {
      color: var(--text-heading);
      font-weight: 600;
      letter-spacing: -0.3px;
    }
    h1 {
      font-size: 2.8rem;
      font-weight: 700;
      line-height: 1.2;
    }
    h2 {
      font-size: 2rem;
      margin-bottom: 1rem;
      position: relative;
      display: inline-block;
    }
    h2::after {
      content: '';
      position: absolute;
      left: 0;
      bottom: -8px;
      width: 48px;
      height: 3px;
      background: var(--primary);
      border-radius: 4px;
    }
    .section-heading-center h2::after {
      left: 50%;
      transform: translateX(-50%);
    }
    a {
      color: var(--primary);
      text-decoration: none;
      transition: color var(--transition);
    }
    a:hover {
      color: var(--accent);
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 20px;
    }
    /* 导航栏 */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.85);
      backdrop-filter: blur(12px);
      z-index: 99;
      border-bottom: 1px solid var(--border-light);
      transition: background 0.3s;
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 70px;
    }
    .logo {
      font-weight: 700;
      font-size: 1.8rem;
      color: var(--text-heading);
      letter-spacing: 1px;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo i {
      color: var(--accent);
      font-size: 2rem;
    }
    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
    }
    .nav-links a {
      color: var(--text-body);
      font-weight: 500;
      font-size: 0.95rem;
      position: relative;
      padding: 4px 0;
    }
    .nav-links a.active,
    .nav-links a:hover {
      color: var(--primary);
    }
    .nav-links a.active::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 100%;
      height: 2px;
      background: var(--primary);
      border-radius: 4px;
    }
    .mobile-toggle {
      display: none;
      background: none;
      border: none;
      font-size: 1.8rem;
      color: var(--text-heading);
    }
    /* 按钮 */
    .btn-primary {
      background: var(--accent);
      color: white;
      padding: 12px 32px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      border: none;
      display: inline-block;
      transition: 0.2s;
      box-shadow: 0 4px 10px rgba(255,107,53,0.25);
    }
    .btn-primary:hover {
      background: var(--accent-dark);
      color: white;
      transform: translateY(-2px);
      box-shadow: 0 8px 18px rgba(255,107,53,0.3);
    }
    .btn-outline {
      color: var(--primary);
      font-weight: 600;
      padding: 10px 24px;
      border-bottom: 2px solid transparent;
      transition: 0.2s;
    }
    .btn-outline:hover {
      border-bottom: 2px solid var(--primary);
      color: var(--primary-dark);
    }
    /* 板块间距 */
    section {
      padding: 90px 0;
    }
    .hero-section {
      padding-top: 140px;
      padding-bottom: 80px;
      background: var(--white);
    }
    .grid-2 {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
    }
    .hero-img {
      border-radius: 16px;
      box-shadow: var(--shadow-lg);
      transition: transform 0.4s;
    }
    .hero-img:hover {
      transform: scale(1.02);
    }
    /* 卡片 */
    .card-feature {
      background: var(--white);
      border-radius: var(--radius-sm);
      padding: 32px 24px;
      box-shadow: var(--shadow-sm);
      transition: all var(--transition);
    }
    .card-feature:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-md);
    }
    .icon-circle {
      font-size: 2rem;
      color: var(--primary);
      margin-bottom: 20px;
      transition: 0.2s;
    }
    .card-feature:hover .icon-circle {
      color: var(--accent);
      transform: scale(1.1);
    }
    .case-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }
    .case-card {
      background: white;
      border-radius: var(--radius-sm);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: all 0.3s;
      display: flex;
      flex-direction: column;
    }
    .case-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-md);
    }
    .case-img {
      height: 200px;
      object-fit: cover;
    }
    .case-content {
      padding: 20px;
    }
    .tag {
      background: #E8F0F4;
      color: var(--primary);
      font-size: 0.75rem;
      padding: 4px 10px;
      border-radius: 20px;
      font-weight: 600;
      display: inline-block;
      margin-bottom: 10px;
    }
    .solution-card {
      background: white;
      border-radius: var(--radius-sm);
      padding: 36px 24px;
      border: 1px solid var(--border-light);
      transition: 0.2s;
    }
    .solution-card.featured {
      border-top: 4px solid var(--accent);
      background: #FCFDFD;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 20px 0;
      cursor: pointer;
    }
    .faq-question {
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      color: var(--text-heading);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: var(--text-body);
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      margin-top: 12px;
    }
    .footer {
      background: #0B1E2E;
      color: #C0C9D3;
      padding: 60px 0 20px;
    }
    .footer a {
      color: #C0C9D3;
    }
    .footer a:hover {
      color: white;
    }
    .contact-form input,
    .contact-form textarea {
      border: none;
      border-bottom: 2px solid #D0D7DE;
      border-radius: 0;
      padding: 12px 4px;
      background: transparent;
      width: 100%;
      margin-bottom: 20px;
      box-shadow: none;
    }
    .contact-form input:focus {
      border-bottom-color: var(--primary);
    }
    @media (max-width: 1024px) {
      .grid-2 {
        grid-template-columns: 1fr;
        gap: 40px;
      }
      .case-grid {
        grid-template-columns: repeat(2,1fr);
      }
      h1 {
        font-size: 2.2rem;
      }
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 70px;
        left: 0;
        background: white;
        width: 100%;
        padding: 20px;
        box-shadow: var(--shadow-md);
      }
      .nav-links.open {
        display: flex;
      }
      .mobile-toggle {
        display: block;
      }
      .case-grid {
        grid-template-columns: 1fr;
      }
      section {
        padding: 60px 0;
      }
    }