/* roulang page: index */
:root {
      --primary: #0A66C2;
      --primary-dark: #084F9E;
      --primary-light: #E8F2FC;
      --accent: #F05A28;
      --accent-dark: #D04A1E;
      --bg: #F7F9FC;
      --card-bg: #FFFFFF;
      --deep-bg: #0F1A2E;
      --text: #1A1F2E;
      --text-weak: #5A6275;
      --border: #E2E8F0;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --shadow-sm: 0 2px 12px rgba(0,0,0,0.06);
      --shadow-md: 0 8px 24px rgba(10,102,194,0.12);
      --shadow-lg: 0 16px 40px rgba(0,0,0,0.12);
      --font-sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Inter", sans-serif;
      --transition: all 0.25s ease;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.7;
      font-size: 16px;
      overflow-x: hidden;
    }

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

    a {
      text-decoration: none;
      color: inherit;
      transition: var(--transition);
    }

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

    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 72px;
      background: rgba(255,255,255,0.85);
      backdrop-filter: blur(12px);
      z-index: 1000;
      display: flex;
      align-items: center;
      border-bottom: 1px solid transparent;
      transition: var(--transition);
    }

    .header.scrolled {
      background: rgba(255,255,255,0.95);
      box-shadow: 0 2px 20px rgba(0,0,0,0.08);
      border-bottom: 1px solid var(--border);
    }

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

    .logo {
      font-weight: 700;
      font-size: 1.5rem;
      letter-spacing: -0.5px;
      color: var(--primary);
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .logo i { font-size: 1.8rem; color: var(--accent); }

    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
    }

    .nav-links a {
      font-weight: 500;
      font-size: 0.95rem;
      color: var(--text);
      position: relative;
      padding-bottom: 4px;
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      left: 0; bottom: 0;
      width: 0; height: 2px;
      background: var(--accent);
      transition: width 0.2s ease;
    }

    .nav-links a:hover::after,
    .nav-links a.active::after { width: 100%; }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: none;
      border: none;
      padding: 8px;
    }
    .hamburger span {
      width: 24px; height: 2px;
      background: var(--text);
      transition: var(--transition);
    }

    /* 移动导航 */
    .mobile-nav {
      position: fixed;
      top: 72px;
      left: 0;
      width: 100%;
      background: white;
      flex-direction: column;
      padding: 24px;
      gap: 20px;
      box-shadow: var(--shadow-lg);
      transform: translateY(-100%);
      opacity: 0;
      transition: transform 0.3s ease, opacity 0.2s ease;
      display: none;
      z-index: 999;
    }
    .mobile-nav.open {
      transform: translateY(0);
      opacity: 1;
    }
    .mobile-nav a {
      font-size: 1.2rem;
      font-weight: 500;
      padding: 8px 0;
      border-bottom: 1px solid var(--border);
    }

    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .mobile-nav { display: flex; }
    }

    /* Hero */
    .hero {
      padding: 140px 0 80px;
      background: linear-gradient(135deg, rgba(10,102,194,0.05) 0%, rgba(15,26,46,0.02) 100%);
      position: relative;
      overflow: hidden;
    }
    .hero-bg-img {
      position: absolute;
      right: -40px;
      top: 50%;
      transform: translateY(-50%);
      max-width: 600px;
      opacity: 0.15;
      pointer-events: none;
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
    }
    .hero-left { flex: 1; }
    .hero-right {
      flex: 1;
      display: flex;
      flex-direction: column;
      gap: 20px;
    }

    .hero h1 {
      font-size: 3rem;
      font-weight: 700;
      letter-spacing: -1px;
      line-height: 1.2;
      margin-bottom: 1.5rem;
      color: var(--text);
    }
    .hero .subtitle {
      font-size: 1.2rem;
      color: var(--text-weak);
      margin-bottom: 2rem;
      max-width: 500px;
    }
    .btn-group { display: flex; gap: 16px; flex-wrap: wrap; }
    .btn {
      display: inline-block;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: var(--transition);
      text-align: center;
      cursor: pointer;
      border: none;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
    }
    .btn-primary:hover { background: var(--primary-dark); transform: translateY(-2px); box-shadow: var(--shadow-md); }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
    }
    .btn-outline:hover { background: var(--primary-light); }
    .btn-accent {
      background: var(--accent);
      color: white;
    }
    .btn-accent:hover { background: var(--accent-dark); }

    .live-stats {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
      background: var(--deep-bg);
      padding: 24px;
      border-radius: var(--radius-card);
      color: white;
    }
    .stat-item {
      text-align: center;
    }
    .stat-number {
      font-family: 'Inter', sans-serif;
      font-size: 2.5rem;
      font-weight: 700;
      color: var(--accent);
    }
    .stat-label { font-size: 0.85rem; color: #B0C4DE; }

    @media (max-width: 1024px) {
      .hero-grid { flex-direction: column; text-align: center; }
      .hero-bg-img { display: none; }
      .hero h1 { font-size: 2.5rem; }
    }

    /* 通用板块 */
    section { padding: 80px 0; }
    .section-title {
      font-size: 2.2rem;
      font-weight: 600;
      text-align: center;
      margin-bottom: 16px;
    }
    .section-sub {
      text-align: center;
      color: var(--text-weak);
      margin-bottom: 48px;
    }

    /* 优势 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    .feature-card {
      background: var(--card-bg);
      padding: 32px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    .feature-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-md); }
    .feature-icon {
      font-size: 2rem;
      color: var(--primary);
      margin-bottom: 16px;
    }
    .feature-card h3 { font-size: 1.3rem; margin-bottom: 8px; }

    @media (max-width: 1024px) { .features-grid { grid-template-columns: repeat(2,1fr); } }
    @media (max-width: 768px) { .features-grid { grid-template-columns: 1fr; } }

    /* 数据看板 */
    .data-section {
      background: var(--deep-bg);
      color: white;
    }
    .dashboard {
      display: flex;
      justify-content: space-around;
      text-align: center;
      flex-wrap: wrap;
    }
    .metric {
      font-family: 'Inter', sans-serif;
      font-size: 3rem;
      font-weight: 700;
    }
    .metric span { color: var(--accent); }

    /* 服务矩阵 */
    .services-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .service-card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      display: flex;
      flex-direction: column;
    }
    .service-card:hover { transform: translateY(-8px); box-shadow: var(--shadow-md); }
    .service-img {
      width: 100%;
      aspect-ratio: 16/9;
      object-fit: cover;
      border-radius: 12px 12px 0 0;
    }
    .service-body { padding: 24px; flex:1; }
    .service-link {
      color: var(--accent);
      font-weight: 600;
      margin-top: 12px;
      display: inline-block;
    }
    @media (max-width: 1024px) { .services-grid { grid-template-columns: repeat(2,1fr); } }
    @media (max-width: 768px) { .services-grid { grid-template-columns: 1fr; } }

    /* 案例对比 */
    .compare-wrapper {
      display: flex;
      gap: 24px;
      align-items: center;
    }
    .compare-col {
      flex:1;
      background: var(--card-bg);
      padding: 24px;
      border-radius: var(--radius-card);
    }
    @media (max-width: 768px) { .compare-wrapper { flex-direction: column; } }

    /* FAQ */
    .faq-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 16px;
    }
    .faq-item {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      padding: 20px;
      cursor: pointer;
      border: 1px solid var(--border);
    }
    .faq-question {
      font-weight: 600;
      display: flex;
      justify-content: space-between;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      margin-top: 12px;
      color: var(--text-weak);
    }
    .faq-item.open .faq-answer { max-height: 200px; }
    @media (max-width: 768px) { .faq-grid { grid-template-columns: 1fr; } }

    /* 表单 */
    .cta-form {
      background: var(--deep-bg);
    }
    .form-card {
      background: white;
      max-width: 560px;
      margin: 0 auto;
      padding: 40px;
      border-radius: 16px;
      box-shadow: var(--shadow-lg);
    }
    .form-group { margin-bottom: 20px; }
    input, select {
      width: 100%;
      padding: 14px;
      border: 1px solid var(--border);
      border-radius: var(--radius-input);
      background: #F8FAFC;
      font-size: 1rem;
    }
    input:focus, select:focus { border-color: var(--primary); outline: none; }

    /* 页脚 */
    .footer {
      background: #EDF1F5;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
    }
    @media (max-width: 768px) { .footer-grid { grid-template-columns: 1fr; } }

    .back-to-top {
      position: fixed;
      bottom: 30px;
      right: 30px;
      background: var(--primary);
      color: white;
      width: 44px;
      height: 44px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      box-shadow: var(--shadow-md);
    }