/* roulang page: index */
:root {
      --primary: #F04E30;
      --primary-deep: #d43e20;
      --secondary-dark: #1A1D2E;
      --white: #ffffff;
      --bg-light: #FAFAFA;
      --border-light: #E5E7EB;
      --text-body: #374151;
      --text-muted: #6B7280;
      --highlight: #FFC107;
      --radius-card: 14px;
      --radius-btn: 10px;
      --shadow-card: 0 8px 20px rgba(0,0,0,0.04), 0 2px 6px rgba(0,0,0,0.02);
      --shadow-hover: 0 16px 32px rgba(240,78,48,0.12), 0 8px 14px rgba(26,29,46,0.06);
      --font-sans: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --font-number: "Inter", "SF Pro Display", system-ui, sans-serif;
      --transition-smooth: 0.25s ease;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-light);
      color: var(--text-body);
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
      scroll-behavior: smooth;
    }

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

    /* 导航 header */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.96);
      backdrop-filter: blur(12px);
      box-shadow: 0 1px 0 rgba(0,0,0,0.02);
      z-index: 100;
      transition: box-shadow var(--transition-smooth), background var(--transition-smooth);
    }

    .header.scrolled {
      box-shadow: 0 4px 20px rgba(0,0,0,0.06);
      background: rgba(255,255,255,0.92);
    }

    .nav-bar {
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 14px 0;
    }

    .logo {
      font-size: 26px;
      font-weight: 800;
      letter-spacing: 1px;
      color: #1F2937;
      display: flex;
      align-items: baseline;
      gap: 8px;
      text-decoration: none;
      z-index: 120;
    }

    .logo span {
      color: var(--primary);
      font-weight: 900;
    }

    .logo small {
      font-size: 12px;
      font-weight: 400;
      color: var(--text-muted);
      letter-spacing: 0.3px;
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 28px;
      list-style: none;
    }

    .nav-links a {
      text-decoration: none;
      font-weight: 500;
      font-size: 15px;
      color: var(--text-body);
      transition: color var(--transition-smooth);
      padding: 4px 0;
    }

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

    .btn-primary {
      background: var(--primary);
      color: white;
      border: none;
      padding: 10px 24px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 15px;
      cursor: pointer;
      transition: background var(--transition-smooth), box-shadow var(--transition-smooth);
      text-decoration: none;
      display: inline-block;
      white-space: nowrap;
    }

    .btn-primary:hover {
      background: var(--primary-deep);
      box-shadow: 0 8px 20px rgba(240,78,48,0.35);
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      z-index: 120;
    }

    .hamburger span {
      width: 26px;
      height: 2.5px;
      background: #1F2937;
      border-radius: 4px;
      transition: var(--transition-smooth);
    }

    /* 主视觉 hero */
    .hero {
      padding: 140px 0 100px;
      background: linear-gradient(135deg, #1A1D2E 0%, #2a2e40 100%);
      position: relative;
      overflow: hidden;
    }

    .hero::before {
      content: "";
      position: absolute;
      top: -50%;
      right: -20%;
      width: 80%;
      height: 200%;
      background: radial-gradient(circle at 70% 40%, rgba(240,78,48,0.25) 0%, transparent 60%);
      pointer-events: none;
    }

    .hero-grid {
      display: flex;
      align-items: center;
      gap: 40px;
      position: relative;
      z-index: 10;
    }

    .hero-text {
      flex: 1 1 50%;
    }

    .hero-text h1 {
      font-size: clamp(2.8rem, 7vw, 4.4rem);
      font-weight: 800;
      color: white;
      line-height: 1.2;
      margin-bottom: 22px;
    }

    .hero-text p {
      color: rgba(255,255,255,0.8);
      font-size: 1.2rem;
      max-width: 500px;
      margin-bottom: 32px;
    }

    .hero-visual {
      flex: 1 1 50%;
      text-align: right;
    }

    .hero-visual img {
      max-width: 100%;
      height: auto;
      border-radius: 24px;
      box-shadow: 0 30px 45px rgba(0,0,0,0.35);
    }

    button, .btn-link {
      cursor: pointer;
    }

    /* 板块间距 */
    section {
      padding: 90px 0;
    }

    .section-title {
      font-size: 2.3rem;
      font-weight: 700;
      color: #111827;
      margin-bottom: 16px;
    }

    .section-sub {
      color: var(--text-muted);
      font-size: 1.1rem;
      margin-bottom: 48px;
    }

    /* 优势卡片 */
    .adv-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }

    .adv-card {
      background: var(--white);
      padding: 32px 24px;
      border-radius: var(--radius-card);
      border: 1px solid var(--border-light);
      box-shadow: var(--shadow-card);
      transition: transform var(--transition-smooth), box-shadow var(--transition-smooth);
    }

    .adv-card:hover {
      transform: translateY(-5px);
      box-shadow: var(--shadow-hover);
      border-color: var(--primary);
    }

    .icon-badge {
      background: rgba(240,78,48,0.08);
      width: 56px;
      height: 56px;
      display: flex;
      align-items: center;
      justify-content: center;
      border-radius: 16px;
      margin-bottom: 20px;
      color: var(--primary);
      font-size: 28px;
    }

    /* 服务矩阵 */
    .services-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }

    .service-card {
      background: white;
      padding: 32px 24px;
      border-radius: var(--radius-card);
      transition: 0.25s;
      border: 1px solid #f0f0f0;
    }

    .service-card:hover {
      border-color: var(--primary);
      box-shadow: 0 12px 28px rgba(240,78,48,0.1);
    }

    .service-icon {
      font-size: 42px;
      margin-bottom: 20px;
    }

    .service-link {
      color: var(--primary);
      font-weight: 600;
      text-decoration: none;
      margin-top: 12px;
      display: inline-block;
    }

    /* 流程+数据 dark */
    .dark-band {
      background: var(--secondary-dark);
      color: white;
    }

    .process-steps {
      display: flex;
      justify-content: space-between;
      align-items: center;
      margin: 40px 0;
    }

    .step-item {
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
    }

    .circle-num {
      background: var(--primary);
      width: 44px;
      height: 44px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      font-size: 20px;
      margin-bottom: 12px;
    }

    .data-row {
      display: flex;
      justify-content: space-around;
      margin-top: 55px;
    }

    .data-item .number {
      font-family: var(--font-number);
      font-size: 3rem;
      font-weight: 700;
      color: var(--highlight);
    }

    /* 案例网格 cases */
    .cases-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr;
      gap: 24px;
    }

    .case-card {
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      transition: 0.25s;
    }

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

    .case-card img {
      width: 100%;
      height: 210px;
      object-fit: cover;
      display: block;
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 18px 0;
    }

    details summary {
      font-weight: 600;
      cursor: pointer;
      list-style: none;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    /* CTA */
    .cta-section {
      background: var(--secondary-dark);
      text-align: center;
      padding: 90px 20px;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 30px;
    }

    @media (max-width: 1024px) {
      .hero-grid {
        flex-direction: column;
      }
      .cases-grid {
        grid-template-columns: 1fr 1fr;
      }
    }

    @media (max-width: 768px) {
      .nav-links {
        display: none;
      }
      .hamburger {
        display: flex;
      }
      .adv-grid,
      .services-grid {
        grid-template-columns: 1fr;
      }
      .process-steps {
        flex-direction: column;
        gap: 25px;
      }
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }