/* roulang page: index */
:root {
      --deep-space: #0B0E14;
      --card-bg: #161B22;
      --primary-purple: #6C5CE7;
      --accent-cyan: #A8E6CF;
      --text-white: #E8ECF1;
      --text-secondary: #8899AA;
      --border-light: rgba(255,255,255,0.06);
      --shadow-card: 0 4px 24px rgba(0,0,0,0.3);
      --shadow-hover: 0 8px 40px rgba(108,92,231,0.15);
      --radius-card: 12px;
      --radius-button: 8px;
      --transition-smooth: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
      --font-sans: 'PingFang SC', 'Microsoft YaHei', 'Noto Sans SC', 'Inter', sans-serif;
    }

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

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--deep-space);
      color: var(--text-white);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

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

    a {
      text-decoration: none;
      color: inherit;
    }

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

    /* 导航 */
    .header-nav {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 72px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0 48px;
      z-index: 1000;
      transition: background 0.3s ease, backdrop-filter 0.3s ease;
      background: transparent;
    }

    .header-nav.scrolled {
      background: rgba(11, 14, 20, 0.92);
      backdrop-filter: blur(16px);
      box-shadow: 0 8px 32px rgba(0,0,0,0.2);
    }

    .logo {
      font-size: 1.8rem;
      font-weight: 700;
      letter-spacing: 1px;
      background: linear-gradient(135deg, #E8ECF1 0%, #A8E6CF 80%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
      display: flex;
      align-items: center;
      gap: 10px;
    }

    .logo i {
      background: none;
      -webkit-text-fill-color: var(--primary-purple);
      font-size: 2rem;
    }

    .nav-links {
      display: flex;
      gap: 40px;
      align-items: center;
    }

    .nav-links a {
      font-size: 0.95rem;
      font-weight: 500;
      color: var(--text-secondary);
      position: relative;
      padding: 8px 0;
      transition: color 0.2s;
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary-purple);
      transition: width 0.3s ease;
    }

    .nav-links a:hover,
    .nav-links a.active {
      color: #fff;
    }

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

    .menu-toggle {
      display: none;
      background: none;
      border: none;
      color: #E8ECF1;
      font-size: 1.8rem;
      cursor: pointer;
      transition: color 0.2s;
    }

    @media (max-width: 768px) {
      .header-nav {
        padding: 0 24px;
      }
      .nav-links {
        position: fixed;
        top: 0;
        right: -100%;
        width: 80%;
        max-width: 320px;
        height: 100vh;
        background: rgba(11,14,20,0.98);
        backdrop-filter: blur(20px);
        flex-direction: column;
        justify-content: center;
        gap: 2rem;
        transition: right 0.4s ease;
        box-shadow: -4px 0 30px rgba(0,0,0,0.5);
      }
      .nav-links.open {
        right: 0;
      }
      .menu-toggle {
        display: block;
        z-index: 1001;
      }
    }

    /* Hero */
    .hero {
      height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
      position: relative;
      overflow: hidden;
      background: radial-gradient(ellipse at 30% 40%, #1a1f35 0%, #0B0E14 70%);
    }

    .star-canvas {
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      z-index: 1;
      pointer-events: none;
    }

    .hero-content {
      position: relative;
      z-index: 2;
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      max-width: 1200px;
      padding: 0 24px;
      gap: 30px;
    }

    .hero-text {
      flex: 1 1 55%;
    }

    .hero-text h1 {
      font-size: clamp(3rem, 6vw, 5rem);
      font-weight: 700;
      letter-spacing: 0.02em;
      line-height: 1.2;
      margin-bottom: 1.8rem;
      background: linear-gradient(to right, #E8ECF1, #ccd6e0);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }

    .hero-text p {
      font-size: 1.25rem;
      color: var(--text-secondary);
      max-width: 500px;
      margin-bottom: 2.8rem;
      line-height: 1.7;
    }

    .btn-group {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }

    .btn-primary {
      background: var(--primary-purple);
      color: white;
      border: none;
      padding: 14px 38px;
      border-radius: var(--radius-button);
      font-weight: 600;
      font-size: 1rem;
      cursor: pointer;
      transition: background 0.3s, box-shadow 0.3s;
      box-shadow: 0 4px 16px rgba(108,92,231,0.4);
      display: inline-block;
      text-align: center;
    }

    .btn-primary:hover {
      background: #7D6FF0;
      box-shadow: 0 8px 24px rgba(108,92,231,0.6);
    }

    .btn-secondary {
      background: transparent;
      border: 1.5px solid var(--primary-purple);
      color: var(--primary-purple);
      padding: 14px 38px;
      border-radius: var(--radius-button);
      font-weight: 600;
      font-size: 1rem;
      cursor: pointer;
      transition: all 0.3s;
    }

    .btn-secondary:hover {
      background: var(--primary-purple);
      color: white;
    }

    .hero-visual {
      flex: 1 1 45%;
      min-height: 320px;
      display: flex;
      align-items: center;
      justify-content: center;
    }

    .star-orbit {
      width: 280px;
      height: 280px;
      border: 2px solid rgba(108,92,231,0.2);
      border-radius: 50%;
      position: relative;
      animation: spin 24s linear infinite;
    }

    .star-orbit::before {
      content: '';
      position: absolute;
      width: 12px;
      height: 12px;
      background: var(--accent-cyan);
      border-radius: 50%;
      top: -6px;
      left: 50%;
      box-shadow: 0 0 20px #A8E6CF;
    }

    @keyframes spin {
      0% { transform: rotate(0deg); }
      100% { transform: rotate(360deg); }
    }

    @media (max-width: 768px) {
      .hero-content {
        flex-direction: column;
        text-align: center;
        margin-top: 60px;
      }
      .hero-text {
        flex: auto;
      }
      .hero-visual {
        display: none;
      }
      .btn-group {
        justify-content: center;
      }
    }

    section {
      padding: 120px 0;
    }

    .section-title {
      font-size: clamp(2rem, 4vw, 2.8rem);
      font-weight: 600;
      margin-bottom: 64px;
      padding-left: 26px;
      border-left: 3px solid var(--primary-purple);
      line-height: 1.3;
      color: #E8ECF1;
    }

    /* 服务交错 */
    .service-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 100px;
      flex-wrap: wrap;
    }

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

    .service-img {
      flex: 1 1 45%;
      border-radius: var(--radius-card);
      overflow: hidden;
      position: relative;
      height: 300px;
      background: #1a1f2b;
    }
    .service-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }
    .service-img::after {
      content: '';
      position: absolute;
      top:0;left:0;width:100%;height:100%;
      background: rgba(108,92,231,0.18);
    }
    .service-text {
      flex: 1 1 50%;
    }
    .service-text h3 {
      font-size: 1.8rem;
      margin-bottom: 1rem;
    }
    .feature-list {
      list-style: none;
      margin-top: 1.8rem;
    }
    .feature-list li {
      margin-bottom: 0.8rem;
      display: flex;
      align-items: center;
      gap: 10px;
      color: #B0BEC5;
    }
    .feature-list li i {
      color: var(--accent-cyan);
    }

    @media (max-width: 768px) {
      .service-row, .service-row.reverse {
        flex-direction: column;
      }
      .service-img {
        height: 240px;
      }
    }

    /* 数据 */
    .stats-grid {
      display: flex;
      justify-content: space-around;
      flex-wrap: wrap;
      gap: 32px;
      text-align: center;
    }
    .stat-item {
      flex: 1 1 180px;
    }
    .stat-number {
      font-size: 2.8rem;
      font-weight: 700;
      color: var(--accent-cyan);
      font-variant-numeric: tabular-nums;
    }
    .stat-label {
      color: var(--text-secondary);
      margin-top: 0.6rem;
    }

    /* 案例卡片 */
    .cases-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 32px;
    }
    .case-card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      border: 1px solid var(--border-light);
      overflow: hidden;
      transition: var(--transition-smooth);
      box-shadow: var(--shadow-card);
    }
    .case-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
    }
    .case-img {
      height: 240px;
      overflow: hidden;
    }
    .case-img img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.4s;
    }
    .case-card:hover .case-img img {
      transform: scale(1.04);
    }
    .case-info {
      padding: 1.8rem;
    }
    .case-tag {
      background: rgba(108,92,231,0.2);
      color: #b9abf7;
      padding: 4px 14px;
      border-radius: 28px;
      font-size: 0.8rem;
      display: inline-block;
      margin-bottom: 0.8rem;
    }
    @media (max-width: 768px) {
      .cases-grid { grid-template-columns: 1fr; }
    }

    /* 时间轴 */
    .timeline-step {
      display: flex;
      gap: 32px;
      margin-bottom: 48px;
    }
    .step-num {
      width: 48px;
      height: 48px;
      background: var(--primary-purple);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      flex-shrink: 0;
    }
    .step-card {
      background: var(--card-bg);
      padding: 1.8rem;
      border-radius: var(--radius-card);
      flex:1;
    }
    @media (max-width: 480px) {
      .timeline-step {
        flex-direction: column;
      }
    }

    /* FAQ */
    .faq-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 24px;
    }
    .faq-item {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      padding: 16px;
      cursor: pointer;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      font-weight: 600;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, margin 0.2s;
      color: #B0BEC5;
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      margin-top: 12px;
    }
    @media (max-width: 768px) {
      .faq-grid { grid-template-columns: 1fr; }
    }

    .cta-banner {
      background: #0B0E14;
      background-image: radial-gradient(rgba(108,92,231,0.08) 1px, transparent 1px);
      background-size: 34px 34px;
      padding: 100px 0;
      text-align: center;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1.5fr 1fr;
      gap: 40px;
      background: #0A0D12;
      padding: 60px 0 40px;
      color: var(--text-secondary);
    }
    @media (max-width: 768px) {
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }