/* roulang page: index */
:root {
      --primary-dark: #1E1E1E;
      --accent-green: #00C896;
      --accent-green-deep: #00A87D;
      --gray-bg: #F4F6F9;
      --text-body: #3A3A3A;
      --text-heading: #1E1E1E;
      --text-muted: #7A7A7A;
      --border-light: #E0E4E8;
      --white: #FFFFFF;
      --footer-bg: #1E1E1E;
      --footer-copy: #151515;
      --font-stack: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --container-max: 1200px;
      --section-gap: 120px;
      --card-radius: 8px;
      --btn-radius: 4px;
      --transition-base: 0.25s ease;
    }

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

    body {
      font-family: var(--font-stack);
      background: var(--white);
      color: var(--text-body);
      font-size: 16px;
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
      padding-top: 80px;
    }

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 24px;
    }

    h1, h2, h3, h4 {
      color: var(--text-heading);
      font-weight: 600;
    }

    h1 {
      font-size: 52px;
      font-weight: 700;
      letter-spacing: -0.5px;
      line-height: 1.2;
      margin-bottom: 1rem;
    }

    h2 {
      font-size: 36px;
      font-weight: 600;
      line-height: 1.3;
      margin-bottom: 1.5rem;
      position: relative;
      display: inline-block;
    }

    h2::after {
      content: "";
      position: absolute;
      left: 0;
      bottom: -10px;
      width: 40px;
      height: 3px;
      background: var(--accent-green);
      border-radius: 2px;
    }

    h3 {
      font-size: 20px;
      font-weight: 600;
      line-height: 1.4;
    }

    p {
      max-width: 680px;
      margin-bottom: 1.2rem;
    }

    a {
      color: var(--text-body);
      text-decoration: none;
      transition: color 0.2s ease;
    }

    a:hover {
      color: var(--accent-green);
    }

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

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font-weight: 600;
      border-radius: var(--btn-radius);
      transition: all var(--transition-base);
      cursor: pointer;
      text-align: center;
      padding: 12px 28px;
      font-size: 16px;
      line-height: 1.2;
      border: 2px solid transparent;
      background: transparent;
      min-width: 140px;
      text-decoration: none;
    }

    .btn-primary {
      background: var(--accent-green);
      color: var(--white);
      border-color: var(--accent-green);
      box-shadow: 0 4px 10px rgba(0,200,150,0.2);
    }

    .btn-primary:hover {
      background: var(--accent-green-deep);
      border-color: var(--accent-green-deep);
      box-shadow: 0 8px 18px rgba(0,200,150,0.35);
      color: white;
      transform: translateY(-1px);
    }

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

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

    .btn-large {
      padding: 16px 36px;
      font-size: 18px;
      min-width: 180px;
    }

    .btn-cta {
      background: var(--accent-green);
      color: white;
      border: none;
      font-weight: 700;
      transition: all 0.3s ease;
      display: inline-flex;
      align-items: center;
      gap: 8px;
    }

    .btn-cta::after {
      content: "\f061";
      font-family: "Font Awesome 6 Free";
      font-weight: 900;
      transition: transform 0.3s ease;
    }

    .btn-cta:hover {
      background: var(--accent-green-deep);
      color: white;
      transform: translateX(4px);
    }

    .btn-cta:hover::after {
      transform: translateX(4px);
    }

    .section {
      padding: var(--section-gap) 0;
    }

    .bg-light {
      background: var(--gray-bg);
    }

    /* 导航栏 */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 80px;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(10px);
      z-index: 100;
      display: flex;
      align-items: center;
      border-bottom: 1px solid transparent;
      transition: all 0.3s ease;
    }

    .site-header.scrolled {
      background: rgba(255,255,255,0.98);
      box-shadow: 0 2px 12px rgba(0,0,0,0.04);
      border-bottom: 1px solid var(--border-light);
    }

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

    .logo {
      font-size: 26px;
      font-weight: 700;
      color: var(--primary-dark);
      letter-spacing: 0.5px;
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .logo i {
      color: var(--accent-green);
      font-size: 32px;
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 36px;
      list-style: none;
    }

    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-body);
      padding: 8px 0;
      border-bottom: 2px solid transparent;
      transition: all 0.2s;
    }

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

    .nav-cta {
      margin-left: 20px;
    }

    .menu-toggle {
      display: none;
      background: none;
      border: none;
      font-size: 28px;
      color: var(--primary-dark);
      cursor: pointer;
    }

    @media (max-width: 1024px) {
      .nav-links {
        display: none;
        position: absolute;
        top: 80px;
        left: 0;
        width: 100%;
        background: white;
        flex-direction: column;
        padding: 24px;
        box-shadow: 0 20px 30px rgba(0,0,0,0.05);
        gap: 20px;
      }
      .nav-links.active {
        display: flex;
      }
      .menu-toggle {
        display: block;
      }
    }

    /* Hero */
    .hero {
      display: flex;
      align-items: center;
      min-height: 80vh;
      background: white;
      position: relative;
      overflow: hidden;
    }

    .hero-content {
      flex: 1;
      z-index: 2;
    }

    .hero-graphic {
      flex: 1;
      display: flex;
      justify-content: center;
      align-items: center;
      position: relative;
    }

    .abstract-geo {
      width: 400px;
      height: 400px;
      background: radial-gradient(circle at 30% 30%, rgba(0,200,150,0.08), transparent 70%);
      border: 2px solid rgba(30,30,30,0.1);
      border-radius: 40% 60% 30% 70% / 50% 40% 60% 50%;
      transform: rotate(15deg);
      position: relative;
    }

    .abstract-geo::after {
      content: "";
      position: absolute;
      width: 120px;
      height: 120px;
      background: var(--accent-green);
      opacity: 0.2;
      border-radius: 30% 70% 70% 30% / 30% 30% 70% 70%;
      top: 40px;
      right: 40px;
    }

    @media (max-width: 768px) {
      .hero {
        flex-direction: column;
        text-align: left;
        padding: 40px 0;
        min-height: auto;
      }
      h1 {
        font-size: 36px;
      }
      .abstract-geo {
        width: 250px;
        height: 250px;
        margin-top: 30px;
      }
    }

    /* 卡片系统 */
    .card {
      background: white;
      border-radius: var(--card-radius);
      padding: 32px;
      box-shadow: 0 2px 12px rgba(0,0,0,0.04);
      transition: all 0.3s ease;
      border: 2px solid transparent;
      height: 100%;
    }

    .card:hover {
      box-shadow: 0 12px 28px rgba(0,0,0,0.08);
      transform: translateY(-4px);
      border-color: var(--accent-green);
    }

    .service-icon {
      font-size: 40px;
      color: var(--accent-green);
      margin-bottom: 20px;
    }

    .case-card img {
      height: 200px;
      object-fit: cover;
      border-radius: 6px 6px 0 0;
    }

    .tag {
      font-size: 12px;
      font-weight: 600;
      color: var(--accent-green);
      border: 1px solid var(--accent-green);
      padding: 2px 10px;
      border-radius: 20px;
      display: inline-block;
      margin: 12px 0 8px;
    }

    /* 数据数字 */
    .stat-number {
      font-size: 42px;
      font-weight: 700;
      color: var(--accent-green);
      font-family: "DIN Alternate", "Arial", sans-serif;
    }

    /* FAQ */
    .accordion-item {
      border-bottom: 1px solid var(--border-light);
      padding: 16px 0;
    }

    .accordion-title {
      font-size: 18px;
      font-weight: 500;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
    }

    .accordion-icon {
      font-size: 24px;
      color: var(--accent-green);
      transition: transform 0.25s ease;
    }

    .accordion-content {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      color: #5A5A5A;
      font-size: 15px;
    }

    .accordion-item.active .accordion-icon {
      transform: rotate(45deg);
    }

    .footer {
      background: var(--footer-bg);
      color: #B0B0B0;
      padding: 60px 0 20px;
    }

    .footer a {
      color: #B0B0B0;
    }

    .footer a:hover {
      color: var(--accent-green);
    }

    .copyright {
      background: var(--footer-copy);
      padding: 16px 0;
      font-size: 13px;
      text-align: center;
      color: #8A8A8A;
    }

    @media (max-width: 640px) {
      .section {
        padding: 60px 0;
      }
      h2 {
        font-size: 28px;
      }
      .stat-number {
        font-size: 30px;
      }
    }