/* roulang page: index */
:root {
      --primary: #4E6EF2;
      --primary-dark: #3B54D4;
      --primary-light: rgba(78, 110, 242, 0.08);
      --green: #00B578;
      --orange: #FF9F0A;
      --red: #FA5151;
      --text-primary: #1F2329;
      --text-secondary: #86909C;
      --bg-light: #F5F6FA;
      --bg-white: #FFFFFF;
      --border: #E5E8EF;
      --shadow-sm: 0 2px 8px rgba(31, 35, 41, 0.04);
      --shadow-md: 0 4px 16px rgba(31, 35, 41, 0.08);
      --shadow-nav: 0 1px 4px rgba(31, 35, 41, 0.06);
      --shadow-btn: 0 4px 12px rgba(78, 110, 242, 0.3);
      --radius-lg: 12px;
      --radius-md: 8px;
      --font-family: system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
      --max-width: 1200px;
      --nav-height: 64px;
    }

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

    body {
      font-family: var(--font-family);
      color: var(--text-primary);
      background-color: var(--bg-white);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 40px;
    }

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

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

    button, input, textarea {
      font-family: inherit;
    }

    /* 导航 */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: rgba(255, 255, 255, 0.95);
      backdrop-filter: blur(12px);
      box-shadow: var(--shadow-nav);
      z-index: 50;
      display: flex;
      align-items: center;
    }

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

    .logo img {
      height: 40px;
      width: auto;
    }

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

    .nav-links a {
      font-size: 14px;
      font-weight: 500;
      color: var(--text-primary);
      padding: 8px 0;
      border-bottom: 2px solid transparent;
      transition: color 0.2s, border-color 0.2s;
    }

    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
      border-bottom-color: var(--primary);
    }

    .nav-cta {
      background: var(--primary);
      color: white !important;
      padding: 10px 24px !important;
      border-radius: var(--radius-md);
      font-weight: 500;
      border: none !important;
      transition: background 0.2s, box-shadow 0.2s;
      margin-left: 16px;
    }

    .nav-cta:hover {
      background: var(--primary-dark);
      box-shadow: var(--shadow-btn);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      cursor: pointer;
      padding: 8px;
    }

    .hamburger span {
      display: block;
      width: 24px;
      height: 2px;
      background: var(--text-primary);
      border-radius: 2px;
      transition: 0.2s;
    }

    /* 区块通用 */
    section {
      padding: 80px 0;
    }

    .section-title {
      font-size: 28px;
      font-weight: 600;
      line-height: 1.4;
      margin-bottom: 16px;
      color: var(--text-primary);
    }

    .section-desc {
      font-size: 16px;
      color: var(--text-secondary);
      max-width: 640px;
      margin-bottom: 40px;
    }

    /* 按钮 */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      border-radius: var(--radius-md);
      font-weight: 500;
      font-size: 16px;
      transition: all 0.2s ease;
      cursor: pointer;
      border: 1.5px solid transparent;
      text-align: center;
    }

    .btn-primary {
      background: var(--primary);
      color: white;
      border-color: var(--primary);
    }

    .btn-primary:hover {
      background: var(--primary-dark);
      border-color: var(--primary-dark);
      box-shadow: var(--shadow-btn);
    }

    .btn-outline {
      background: transparent;
      color: var(--primary);
      border-color: var(--primary);
    }

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

    .btn-ghost {
      background: transparent;
      color: white;
      border-color: white;
    }

    .btn-ghost:hover {
      background: rgba(255,255,255,0.15);
    }

    /* Hero */
    #hero {
      padding-top: calc(var(--nav-height) + 60px);
      background: var(--bg-light);
      position: relative;
      overflow: hidden;
    }

    .hero-grid {
      display: flex;
      align-items: center;
      gap: 48px;
    }

    .hero-content {
      flex: 1;
      max-width: 560px;
    }

    .hero-content h1 {
      font-size: 36px;
      font-weight: 700;
      line-height: 1.3;
      margin-bottom: 16px;
    }

    .hero-subtitle {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 24px;
    }

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

    .hero-image {
      flex: 1;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      border-radius: var(--radius-lg);
      min-height: 360px;
      box-shadow: var(--shadow-md);
    }

    /* 卡片 */
    .card-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 32px;
    }

    .feature-card {
      background: var(--bg-white);
      padding: 32px;
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-sm);
      transition: transform 0.25s ease, box-shadow 0.25s ease;
    }

    .feature-card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }

    .icon-box {
      width: 64px;
      height: 64px;
      background: #EEF1FF;
      border-radius: var(--radius-md);
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 20px;
      color: var(--primary);
      font-size: 28px;
    }

    .feature-card h3 {
      font-size: 20px;
      font-weight: 600;
      margin-bottom: 12px;
    }

    /* 解决方案交替布局 */
    .solution-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 80px;
    }

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

    .solution-text {
      flex: 1;
    }

    .solution-text h2 {
      font-size: 28px;
      font-weight: 600;
      margin-bottom: 16px;
    }

    .solution-list {
      list-style: none;
      margin-top: 20px;
    }

    .solution-list li {
      display: flex;
      align-items: center;
      gap: 12px;
      margin-bottom: 12px;
      color: var(--text-primary);
    }

    .solution-list i {
      color: var(--green);
      font-size: 18px;
    }

    .solution-image {
      flex: 1;
      border-radius: var(--radius-lg);
      overflow: hidden;
      box-shadow: var(--shadow-md);
    }

    .solution-image img {
      width: 100%;
      height: auto;
      object-fit: cover;
    }

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

    .case-card {
      background: var(--bg-white);
      border-radius: var(--radius-lg);
      padding: 28px;
      box-shadow: var(--shadow-sm);
      transition: 0.2s;
    }

    .case-card:hover {
      box-shadow: var(--shadow-md);
    }

    .case-icon {
      font-size: 32px;
      color: var(--primary);
      margin-bottom: 16px;
    }

    .case-highlight {
      font-size: 24px;
      font-weight: 700;
      color: var(--primary);
      margin: 12px 0 8px;
    }

    /* FAQ */
    #faq {
      background: var(--bg-light);
    }

    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }

    .faq-item {
      border-bottom: 1px solid var(--border);
      padding: 16px 0;
    }

    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      font-weight: 500;
      font-size: 18px;
      background: none;
      border: none;
      width: 100%;
      text-align: left;
      color: var(--text-primary);
    }

    .faq-icon {
      font-size: 20px;
      transition: transform 0.2s;
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.25s ease-out, padding 0.2s;
      color: var(--text-secondary);
      font-size: 16px;
      padding-top: 0;
    }

    .faq-item.open .faq-answer {
      max-height: 200px;
      padding-top: 12px;
    }

    .faq-item.open .faq-icon {
      transform: rotate(45deg);
    }

    /* CTA */
    #contact {
      background: linear-gradient(135deg, #4E6EF2 0%, #6B8AFF 100%);
      color: white;
      text-align: center;
    }

    .contact-card {
      background: white;
      border-radius: var(--radius-lg);
      padding: 40px;
      max-width: 520px;
      margin: 40px auto 0;
      box-shadow: var(--shadow-md);
      color: var(--text-primary);
    }

    .form-group {
      margin-bottom: 20px;
    }

    .form-group input,
    .form-group textarea {
      width: 100%;
      padding: 12px 16px;
      border: 1px solid var(--border);
      border-radius: var(--radius-md);
      font-size: 16px;
      transition: border 0.2s, box-shadow 0.2s;
    }

    .form-group input:focus,
    .form-group textarea:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(78,110,242,0.15);
    }

    /* 页脚 */
    #footer {
      background: #1F2329;
      color: #86909C;
      padding: 40px 0;
      text-align: center;
    }

    .footer-links {
      display: flex;
      justify-content: center;
      gap: 32px;
      margin: 16px 0;
    }

    .footer-links a {
      color: #86909C;
      transition: color 0.2s;
    }

    .footer-links a:hover {
      color: white;
    }

    /* 响应式 */
    @media (max-width: 1024px) {
      .container {
        padding: 0 24px;
      }
      .card-grid,
      .case-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }

    @media (max-width: 768px) {
      :root {
        --nav-height: 56px;
      }
      .nav-links {
        display: none;
        position: absolute;
        top: var(--nav-height);
        left: 0;
        width: 100%;
        background: rgba(255,255,255,0.98);
        backdrop-filter: blur(12px);
        flex-direction: column;
        padding: 24px;
        border-radius: 0 0 var(--radius-lg) var(--radius-lg);
        box-shadow: var(--shadow-md);
        gap: 20px;
      }
      .nav-links.active {
        display: flex;
      }
      .hamburger {
        display: flex;
      }
      .nav-cta {
        margin-left: 0;
        width: 100%;
      }
      .hero-grid {
        flex-direction: column;
      }
      .hero-image {
        min-height: 240px;
        width: 100%;
      }
      .card-grid,
      .case-grid {
        grid-template-columns: 1fr;
      }
      .solution-row,
      .solution-row.reverse {
        flex-direction: column;
      }
      section {
        padding: 48px 0;
      }
    }