/* roulang page: index */
:root {
      --primary: #7B2FF7;
      --primary-glow: #9D5CFF;
      --accent: #00E5FF;
      --bg-dark: #1A1A1A;
      --bg-deeper: #0F0F0F;
      --surface: rgba(255, 255, 255, 0.04);
      --border-light: rgba(255, 255, 255, 0.08);
      --border-strong: rgba(255, 255, 255, 0.18);
      --text-primary: #FFFFFF;
      --text-secondary: #B0B0C0;
      --text-muted: #707085;
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 20px;
      --shadow-card: 0 8px 24px rgba(0,0,0,0.5);
      --shadow-glow: 0 0 24px rgba(0, 229, 255, 0.25);
      --transition: 0.25s ease;
      --max-width: 1200px;
      --nav-height: 72px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    html {
      scroll-behavior: smooth;
    }
    body {
      font-family: 'Inter', 'PingFang SC', 'Microsoft YaHei', system-ui, -apple-system, sans-serif;
      background-color: var(--bg-dark);
      color: var(--text-primary);
      line-height: 1.7;
      font-weight: 400;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    img {
      max-width: 100%;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    /* 导航 */
    .nav-bar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      background: rgba(26, 26, 26, 0.94);
      backdrop-filter: blur(10px);
      border-bottom: 1px solid rgba(255,255,255,0.08);
      z-index: 100;
      display: flex;
      align-items: center;
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-weight: 800;
      font-size: 1.6rem;
      background: linear-gradient(135deg, var(--primary) 0%, var(--accent) 90%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
      letter-spacing: 0.5px;
    }
    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
    }
    .nav-links a {
      font-weight: 500;
      color: var(--text-secondary);
      transition: color var(--transition);
      font-size: 0.95rem;
      position: relative;
      padding: 6px 0;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--accent);
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent);
      transition: width var(--transition);
    }
    .nav-links a:hover::after,
    .nav-links a.active::after {
      width: 100%;
    }
    .menu-toggle {
      display: none;
      background: none;
      border: none;
      color: white;
      font-size: 1.8rem;
      cursor: pointer;
    }
    /* 移动端菜单 */
    @media (max-width: 768px) {
      .nav-links {
        position: fixed;
        top: var(--nav-height);
        left: 0;
        width: 100%;
        background: var(--bg-deeper);
        flex-direction: column;
        padding: 2rem;
        gap: 1.5rem;
        transform: translateY(-120%);
        transition: transform 0.3s ease;
        border-bottom: 1px solid rgba(255,255,255,0.1);
      }
      .nav-links.open {
        transform: translateY(0);
      }
      .menu-toggle {
        display: block;
      }
    }
    /* Hero */
    .hero {
      padding: 140px 0 80px;
      background: radial-gradient(circle at 30% 40%, rgba(123,47,247,0.18) 0%, rgba(26,26,26,1) 75%);
      display: flex;
      align-items: center;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 2.5rem;
      align-items: center;
    }
    .hero-content h1 {
      font-size: clamp(2.4rem, 5vw, 3.8rem);
      font-weight: 800;
      line-height: 1.2;
      margin-bottom: 1.5rem;
      background: linear-gradient(to right, #fff, #e0e0ff);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }
    .hero-content .subtitle {
      font-size: 1.2rem;
      color: var(--text-secondary);
      margin-bottom: 2rem;
      max-width: 480px;
    }
    .btn-group {
      display: flex;
      gap: 1rem;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      font-weight: 600;
      padding: 0.85rem 2.2rem;
      border-radius: var(--radius-sm);
      border: none;
      cursor: pointer;
      transition: background var(--transition), color var(--transition);
      display: inline-flex;
      align-items: center;
      gap: 0.5rem;
    }
    .btn-primary:hover {
      background: var(--accent);
      color: #1A1A1A;
    }
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--accent);
      color: var(--accent);
      font-weight: 600;
      padding: 0.85rem 2.2rem;
      border-radius: var(--radius-sm);
      cursor: pointer;
      transition: all var(--transition);
    }
    .btn-outline:hover {
      background: var(--accent);
      color: #1A1A1A;
    }
    .hero-image {
      background: url('/assets/images/backpic/back-1.webp') center/cover no-repeat;
      border-radius: var(--radius-lg);
      height: 380px;
      border: 1px solid rgba(0,229,255,0.3);
      box-shadow: 0 0 30px rgba(0,229,255,0.15);
    }
    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
      }
      .hero-image {
        height: 260px;
        order: -1;
      }
    }
    /* 通用板块 */
    section {
      padding: 90px 0;
    }
    .section-title {
      font-size: 2.2rem;
      font-weight: 700;
      margin-bottom: 1rem;
      text-align: center;
    }
    .section-sub {
      color: var(--text-secondary);
      text-align: center;
      max-width: 600px;
      margin: 0 auto 3.5rem;
    }
    /* 优势卡片 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    .feature-card {
      background: var(--surface);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 2rem 1.5rem;
      transition: all var(--transition);
    }
    .feature-card:hover {
      border-color: var(--accent);
      box-shadow: var(--shadow-glow);
    }
    .feature-icon {
      font-size: 2.2rem;
      color: var(--accent);
      margin-bottom: 1.2rem;
    }
    .feature-card h3 {
      font-size: 1.3rem;
      margin-bottom: 0.8rem;
    }
    @media (max-width: 900px) {
      .features-grid { grid-template-columns: repeat(2, 1fr); }
    }
    @media (max-width: 520px) {
      .features-grid { grid-template-columns: 1fr; }
    }
    /* 数据块 */
    .data-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    .data-item {
      text-align: center;
      padding: 2rem 1rem;
      background: var(--surface);
      border-radius: var(--radius-md);
      border: 1px solid var(--border-light);
    }
    .data-number {
      font-size: 2.8rem;
      font-weight: 800;
      color: var(--accent);
      display: block;
      margin-bottom: 0.3rem;
    }
    .data-label {
      color: var(--text-secondary);
      border-top: 2px solid var(--accent);
      display: inline-block;
      padding-top: 0.5rem;
    }
    @media (max-width: 768px) {
      .data-grid { grid-template-columns: repeat(2, 1fr); }
    }
    /* 案例交替 */
    .case-row {
      display: flex;
      align-items: center;
      gap: 2.5rem;
      margin-bottom: 3rem;
    }
    .case-row.reverse {
      flex-direction: row-reverse;
    }
    .case-img {
      flex: 1;
      height: 240px;
      background-size: cover;
      background-position: center;
      border-radius: var(--radius-md);
      border: 1px solid rgba(0,229,255,0.25);
    }
    .case-text {
      flex: 1;
    }
    .case-text h3 {
      font-size: 1.6rem;
      margin-bottom: 1rem;
    }
    @media (max-width: 768px) {
      .case-row, .case-row.reverse {
        flex-direction: column;
      }
      .case-img { width: 100%; height: 200px; }
    }
    /* 解决方案 */
    .solution-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .solution-card {
      background: var(--surface);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 2rem;
    }
    .solution-card i {
      font-size: 2rem;
      color: var(--accent);
      margin-bottom: 1rem;
    }
    @media (max-width: 768px) {
      .solution-grid { grid-template-columns: 1fr; }
    }
    /* FAQ */
    .faq-item {
      background: var(--surface);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-sm);
      margin-bottom: 0.8rem;
      overflow: hidden;
    }
    .faq-question {
      padding: 1.2rem 1.5rem;
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: rgba(0,0,0,0.3);
      padding: 0 1.5rem;
      color: var(--text-secondary);
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 1rem 1.5rem;
    }
    .faq-item.active {
      border-color: var(--accent);
    }
    /* CTA */
    .cta-band {
      background: linear-gradient(135deg, #2a1a3a, #0f1a2b);
      text-align: center;
      padding: 70px 0;
    }
    /* 表单 */
    .contact-form {
      max-width: 620px;
      margin: 0 auto;
      display: flex;
      flex-direction: column;
      gap: 1.2rem;
    }
    .contact-form input,
    .contact-form textarea {
      background: rgba(255,255,255,0.06);
      border: 1px solid rgba(255,255,255,0.2);
      border-radius: var(--radius-sm);
      padding: 0.9rem 1.2rem;
      color: white;
      font-size: 1rem;
      outline: none;
    }
    .contact-form input:focus,
    .contact-form textarea:focus {
      border-color: var(--accent);
    }
    /* 页脚 */
    .footer {
      background: var(--bg-deeper);
      padding: 60px 0 30px;
      border-top: 1px solid rgba(255,255,255,0.06);
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 2rem;
    }
    .footer a {
      color: var(--text-muted);
      font-size: 0.9rem;
    }
    .footer a:hover {
      color: var(--accent);
    }
    @media (max-width: 768px) {
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }