/* roulang page: index */
:root {
      --primary: #4E6EF2;
      --primary-dark: #3A5CE4;
      --green: #00B578;
      --orange: #FF9F0A;
      --red: #FA5151;
      --bg: #F5F6FA;
      --bg-alt: #F0F2F8;
      --card: #FFFFFF;
      --text: #1F2329;
      --text-secondary: #86909C;
      --text-light: #B0B8C1;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-badge: 16px;
      --shadow-sm: 0 2px 8px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 24px rgba(0,0,0,0.08);
      --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
      --nav-height: 64px;
    }

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

    html {
      scroll-behavior: smooth;
      font-family: var(--font-family);
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.5;
    }

    body {
      min-height: 100vh;
      display: flex;
      flex-direction: column;
    }

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

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

    button, .btn {
      font-family: inherit;
      cursor: pointer;
      border: none;
      background: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      transition: all 0.2s ease-out;
      font-weight: 500;
      border-radius: var(--radius-btn);
    }

    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
    }

    @media (max-width: 768px) {
      .container {
        padding: 0 16px;
      }
    }

    /* 导航 */
    #nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      z-index: 100;
      backdrop-filter: blur(8px);
      background: rgba(255,255,255,0.7);
      transition: background 0.3s, box-shadow 0.3s;
      display: flex;
      align-items: center;
    }

    #nav.scrolled {
      background: rgba(255,255,255,0.95);
      box-shadow: 0 1px 0 rgba(0,0,0,0.06);
      backdrop-filter: blur(12px);
    }

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

    .logo {
      font-size: 24px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 1px;
      display: flex;
      align-items: center;
    }

    .logo span {
      margin-left: 6px;
      font-size: 18px;
      font-weight: 400;
      color: var(--text-secondary);
    }

    .nav-links {
      display: flex;
      gap: 28px;
      align-items: center;
    }

    .nav-links a {
      font-size: 16px;
      color: var(--text-secondary);
      padding: 4px 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);
    }

    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 10px 24px;
      border-radius: var(--radius-btn);
      box-shadow: 0 2px 8px rgba(78,110,242,0.3);
    }

    .btn-primary:hover {
      background: var(--primary-dark);
      box-shadow: 0 4px 14px rgba(78,110,242,0.4);
      transform: translateY(-1px);
    }

    .mobile-nav {
      display: none;
    }

    @media (max-width: 768px) {
      .desktop-nav-links {
        display: none;
      }
      .mobile-nav {
        display: flex;
        position: fixed;
        bottom: 0;
        left: 0;
        width: 100%;
        height: 64px;
        background: white;
        box-shadow: 0 -2px 12px rgba(0,0,0,0.06);
        justify-content: space-around;
        align-items: center;
        z-index: 110;
        padding: 0 8px;
      }
      .mobile-nav a {
        display: flex;
        flex-direction: column;
        align-items: center;
        font-size: 11px;
        color: var(--text-secondary);
        gap: 4px;
        padding: 8px 12px;
        border-radius: 12px;
        transition: color 0.2s;
        min-width: 48px;
        min-height: 48px;
        justify-content: center;
      }
      .mobile-nav a i {
        font-size: 20px;
        stroke-width: 2;
      }
    }

    /* Hero */
    #hero {
      min-height: 100vh;
      display: flex;
      align-items: center;
      background: linear-gradient(135deg, #FFFFFF 0%, #F5F6FA 100%);
      padding-top: var(--nav-height);
    }

    .hero-grid {
      display: flex;
      align-items: center;
      gap: 60px;
      width: 100%;
    }

    .hero-text {
      flex: 1;
    }

    .hero-text h1 {
      font-size: 48px;
      font-weight: 700;
      color: var(--text);
      line-height: 1.3;
      margin-bottom: 20px;
    }

    .hero-text p {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 32px;
      max-width: 480px;
    }

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

    .btn-outline {
      border: 1px solid var(--primary);
      color: var(--primary);
      background: transparent;
      padding: 10px 24px;
    }

    .btn-outline:hover {
      background: rgba(78,110,242,0.04);
      transform: translateY(-1px);
    }

    .hero-graphic {
      flex: 1;
      position: relative;
      height: 480px;
    }

    @media (max-width: 768px) {
      .hero-grid {
        flex-direction: column;
        gap: 40px;
        text-align: center;
      }
      .hero-text h1 {
        font-size: 36px;
      }
      .hero-text p {
        font-size: 16px;
        margin-left: auto;
        margin-right: auto;
      }
      .hero-buttons {
        justify-content: center;
      }
      .hero-graphic {
        height: 300px;
        width: 100%;
      }
    }

    .abstract-shape {
      width: 100%;
      height: 100%;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .circle-anim {
      width: 280px;
      height: 280px;
      border-radius: 50%;
      background: radial-gradient(circle at 30% 30%, rgba(78,110,242,0.15), rgba(0,181,120,0.1));
      animation: float 6s infinite ease-in-out;
      position: relative;
    }

    .arc {
      position: absolute;
      border: 3px solid transparent;
      border-top-color: var(--primary);
      border-radius: 50%;
      animation: spin 12s linear infinite;
      opacity: 0.6;
    }

    @keyframes float {
      0% { transform: translateY(0px); }
      50% { transform: translateY(-15px); }
      100% { transform: translateY(0px); }
    }
    @keyframes spin {
      0% { transform: rotate(0deg); }
      100% { transform: rotate(360deg); }
    }

    .section {
      padding: 100px 0;
    }

    @media (max-width: 768px) {
      .section {
        padding: 72px 0;
      }
    }

    .section-title {
      text-align: center;
      font-size: 32px;
      font-weight: 700;
      margin-bottom: 16px;
      color: var(--text);
    }

    .section-sub {
      text-align: center;
      color: var(--text-secondary);
      margin-bottom: 48px;
    }

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

    @media (max-width: 768px) {
      .grid-3 {
        grid-template-columns: 1fr;
      }
    }

    .service-card {
      background: var(--card);
      padding: 32px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      transition: all 0.2s ease;
    }

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

    .service-icon {
      font-size: 40px;
      color: var(--primary);
      margin-bottom: 16px;
    }

    .service-card h3 {
      font-size: 20px;
      margin-bottom: 8px;
    }

    .service-link {
      color: var(--primary);
      margin-top: 16px;
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }

    /* 数据 */
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }

    @media (max-width: 768px) {
      .grid-4 {
        grid-template-columns: 1fr 1fr;
      }
    }

    .stat-item {
      text-align: center;
    }

    .stat-number {
      font-size: 36px;
      font-weight: 700;
      color: var(--primary);
    }

    /* 案例滚动 */
    .cases-scroll {
      display: flex;
      gap: 24px;
      overflow-x: auto;
      padding-bottom: 12px;
      scrollbar-width: thin;
    }

    .case-card {
      min-width: 320px;
      background: white;
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      transition: box-shadow 0.2s;
    }

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

    .case-img {
      height: 180px;
      background-size: cover;
      transition: transform 0.3s ease;
    }

    .case-card:hover .case-img {
      transform: scale(1.03);
    }

    /* 解决方案左右交替 */
    .solution-row {
      display: flex;
      align-items: center;
      gap: 48px;
      margin-bottom: 64px;
    }

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

    @media (max-width: 768px) {
      .solution-row, .solution-row.reverse {
        flex-direction: column;
      }
    }

    /* FAQ */
    .faq-item {
      border-bottom: 1px solid #e5e7eb;
    }

    .faq-question {
      padding: 20px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      cursor: pointer;
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: #F7F8FC;
      padding: 0 16px;
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 16px;
    }

    /* CTA */
    #cta {
      background: linear-gradient(135deg, rgba(78,110,242,0.06), rgba(0,181,120,0.04));
      text-align: center;
    }

    .glow-btn {
      box-shadow: 0 0 20px rgba(78,110,242,0.4);
    }

    footer {
      background: #1F2329;
      color: #B0B8C1;
      padding: 60px 0 20px;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
    }

    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }