/* roulang page: index */
:root {
      --bg-deep: #0A0E17;
      --bg-card: #131A26;
      --accent-red: #E63946;
      --accent-red-hover: #C1121F;
      --text-white: #F1FAEE;
      --text-muted: #A8B2C1;
      --mint-green: #2EC4B6;
      --border-light: rgba(255,255,255,0.06);
      --radius-sm: 4px;
      --radius-md: 8px;
      --shadow-card: 0 1px 2px rgba(0,0,0,0.4), 0 4px 16px rgba(0,0,0,0.25);
      --font-sans: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", sans-serif;
      --font-number: "Inter", "SF Pro Display", sans-serif;
      --container-max: 1280px;
      --section-gap: 120px;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--bg-deep);
      color: var(--text-muted);
      line-height: 1.75;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: var(--container-max);
      margin: 0 auto;
      padding: 0 40px;
    }

    h1, h2, h3, h4 {
      color: var(--text-white);
      font-weight: 700;
      letter-spacing: -0.01em;
    }

    h1 {
      font-size: 56px;
      line-height: 1.1;
      font-weight: 800;
      letter-spacing: -0.02em;
    }

    h2 {
      font-size: 40px;
      margin-bottom: 16px;
    }

    h3 {
      font-size: 24px;
      font-weight: 600;
    }

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

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

    button {
      font-family: inherit;
      cursor: pointer;
    }

    /* 导航 */
    .main-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 64px;
      background: rgba(10,14,23,0.85);
      backdrop-filter: blur(12px);
      z-index: 1000;
      display: flex;
      align-items: center;
      border-bottom: 1px solid transparent;
    }

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

    .logo {
      font-size: 24px;
      font-weight: 800;
      color: var(--text-white);
      letter-spacing: -0.5px;
    }
    .logo span {
      color: var(--accent-red);
    }

    .nav-links {
      display: flex;
      gap: 32px;
    }

    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-muted);
      position: relative;
      padding: 4px 0;
      transition: color 0.25s;
      text-transform: uppercase;
      letter-spacing: 0.5px;
    }

    .nav-links a:hover,
    .nav-links a.active {
      color: var(--text-white);
    }

    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-red);
      transition: width 0.3s ease;
    }

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

    .mobile-nav {
      display: none;
    }

    /* 按钮 */
    .btn-primary {
      background: var(--accent-red);
      color: var(--text-white);
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      border: none;
      display: inline-block;
      transition: background 0.25s ease, transform 0.25s ease;
      letter-spacing: 0.3px;
    }
    .btn-primary:hover {
      background: var(--accent-red-hover);
      transform: translateY(-2px);
    }

    .btn-outline {
      background: transparent;
      border: 1px solid var(--text-white);
      color: var(--text-white);
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      display: inline-block;
      transition: background 0.25s ease, transform 0.25s ease;
    }
    .btn-outline:hover {
      background: rgba(255,255,255,0.05);
      transform: translateY(-2px);
    }

    /* Hero */
    .hero {
      padding: 160px 0 100px;
      display: flex;
      align-items: center;
      gap: 60px;
      position: relative;
    }
    .hero-left {
      flex: 0 0 55%;
    }
    .hero-right {
      flex: 1;
      display: flex;
      justify-content: center;
      animation: float 4s ease-in-out infinite;
    }
    @keyframes float {
      0% { transform: translateY(0); }
      50% { transform: translateY(-8px); }
      100% { transform: translateY(0); }
    }
    .hero h1 {
      margin-bottom: 24px;
    }
    .hero-sub {
      font-size: 20px;
      color: var(--accent-red);
      font-weight: 600;
      margin-bottom: 16px;
    }
    .hero-desc {
      font-size: 18px;
      margin-bottom: 40px;
      max-width: 500px;
    }
    .hero-buttons {
      display: flex;
      gap: 20px;
      flex-wrap: wrap;
    }
    .hero-image {
      max-width: 360px;
      border-radius: 24px;
      box-shadow: 0 20px 40px rgba(0,0,0,0.6);
    }

    /* 板块通用 */
    section {
      padding: var(--section-gap) 0;
    }
    .section-title {
      margin-bottom: 48px;
    }

    /* 特点网格 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 32px;
    }
    .feature-card {
      background: var(--bg-card);
      padding: 32px;
      border-radius: var(--radius-md);
      transition: transform 0.35s ease, box-shadow 0.35s ease;
      border: 1px solid var(--border-light);
    }
    .feature-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-card);
    }
    .feature-icon {
      width: 40px;
      height: 40px;
      margin-bottom: 20px;
      color: var(--accent-red);
      transition: color 0.2s;
    }
    .feature-card:hover .feature-icon {
      color: var(--text-white);
    }
    .feature-card h3 {
      margin-bottom: 12px;
    }

    /* 数据亮点 */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      text-align: center;
      gap: 40px;
    }
    .stat-number {
      font-family: var(--font-number);
      font-size: 48px;
      font-weight: 800;
      color: var(--mint-green);
      line-height: 1.2;
    }
    .stat-label {
      font-size: 13px;
      text-transform: uppercase;
      letter-spacing: 0.08em;
      color: var(--text-muted);
      margin-top: 8px;
    }

    /* 案例 */
    .cases-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 32px;
    }
    .case-card {
      background: var(--bg-card);
      border-radius: var(--radius-md);
      overflow: hidden;
      transition: transform 0.35s ease, box-shadow 0.35s ease;
    }
    .case-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-card);
    }
    .case-img {
      width: 100%;
      height: 220px;
      object-fit: cover;
      transition: transform 0.4s ease;
    }
    .case-card:hover .case-img {
      transform: scale(1.03);
    }
    .case-content {
      padding: 24px;
    }
    .case-tag {
      display: inline-block;
      background: var(--accent-red);
      color: white;
      font-size: 12px;
      padding: 4px 12px;
      border-radius: var(--radius-sm);
      margin-bottom: 12px;
      font-weight: 600;
    }

    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 20px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      color: var(--text-white);
      cursor: pointer;
      font-size: 18px;
      transition: color 0.2s;
    }
    .faq-question:hover {
      color: var(--accent-red);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      color: var(--text-muted);
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 16px;
    }
    .faq-item.active .faq-question {
      color: var(--accent-red);
    }
    .faq-indicator {
      font-size: 24px;
      transition: transform 0.3s;
    }
    .faq-item.active .faq-indicator {
      transform: rotate(45deg);
    }

    /* CTA */
    .cta-section {
      background: #0D1321;
      text-align: center;
      padding: 100px 0;
    }
    .cta-section h2 {
      margin-bottom: 24px;
    }
    .cta-small {
      margin-top: 16px;
      font-size: 14px;
    }

    /* 页脚 */
    .footer {
      padding: 60px 0 30px;
      border-top: 1px solid var(--border-light);
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr;
      gap: 40px;
    }
    .footer-logo {
      font-size: 24px;
      font-weight: 800;
      color: white;
      margin-bottom: 12px;
    }
    .social-icons {
      display: flex;
      gap: 16px;
      margin-top: 20px;
    }
    .social-icons a {
      color: var(--text-muted);
      transition: color 0.2s;
    }
    .social-icons a:hover {
      color: var(--accent-red);
    }
    .copyright {
      margin-top: 40px;
      color: var(--text-muted);
      font-size: 14px;
      text-align: center;
    }

    /* 响应式 */
    @media (max-width: 1024px) {
      .container { padding: 0 24px; }
      .hero { flex-direction: column; padding: 120px 0 60px; }
      .hero-left { flex: auto; text-align: center; }
      .hero-desc { max-width: 100%; }
      .features-grid { grid-template-columns: repeat(2, 1fr); }
    }
    @media (max-width: 768px) {
      h1 { font-size: 34px; }
      h2 { font-size: 28px; }
      h3 { font-size: 20px; }
      .nav-links { display: none; }
      .mobile-nav {
        display: flex;
        position: fixed;
        bottom: 16px;
        left: 16px;
        right: 16px;
        background: #131A26;
        border-radius: 16px;
        padding: 8px 20px;
        justify-content: space-around;
        z-index: 999;
        backdrop-filter: blur(12px);
      }
      .mobile-nav a {
        color: var(--text-muted);
        font-size: 12px;
        display: flex;
        flex-direction: column;
        align-items: center;
        gap: 4px;
      }
      .mobile-nav a.active {
        color: var(--accent-red);
      }
      .features-grid { grid-template-columns: 1fr; }
      .stats-grid { grid-template-columns: 1fr 1fr; }
      .cases-grid { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
      .hero-image { max-width: 260px; }
    }