/* roulang page: index */
:root {
      --deep-space: #0A0E17;
      --racing-red: #E63946;
      --ice-white: #F1FAEE;
      --glacier-cyan: #A8DADC;
      --text-primary: #F1FAEE;
      --text-secondary: rgba(241, 250, 238, 0.7);
      --text-muted: rgba(241, 250, 238, 0.5);
      --card-bg: rgba(20, 25, 35, 0.8);
      --card-solid: #141923;
      --border-dim: rgba(255, 255, 255, 0.08);
      --border-hover: #A8DADC;
      --radius-sm: 4px;
      --radius-md: 6px;
      --shadow-glow: 0 0 12px rgba(230, 57, 70, 0.4);
      --container-max: 1280px;
      --space-section: 120px;
      --font-sans: 'Inter', 'PingFang SC', 'Microsoft YaHei', 'SF Pro Display', system-ui, -apple-system, sans-serif;
    }

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

    html {
      scroll-behavior: smooth;
      background-color: var(--deep-space);
    }

    body {
      font-family: var(--font-sans);
      background-color: var(--deep-space);
      color: var(--text-primary);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
      overflow-x: hidden;
    }

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

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

    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: none;
      transition: all 0.25s ease;
      font-weight: 600;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
    }

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

    /* 导航系统 */
    .main-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      z-index: 1000;
      background: rgba(10, 14, 23, 0.85);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-dim);
      transition: background 0.3s;
    }

    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }

    .logo {
      font-size: 1.8rem;
      font-weight: 700;
      letter-spacing: -0.5px;
      color: var(--ice-white);
    }
    .logo span {
      color: var(--racing-red);
    }

    .desktop-nav {
      display: flex;
      gap: 36px;
      align-items: center;
    }

    .desktop-nav a {
      font-size: 0.95rem;
      font-weight: 500;
      color: var(--text-secondary);
      padding: 6px 0;
      border-bottom: 2px solid transparent;
      transition: color 0.2s, border-color 0.2s;
    }

    .desktop-nav a:hover,
    .desktop-nav a.active {
      color: var(--ice-white);
      border-bottom-color: var(--glacier-cyan);
    }

    .mobile-nav {
      display: none;
      position: fixed;
      bottom: 0;
      left: 0;
      width: 100%;
      background: rgba(10, 14, 23, 0.95);
      backdrop-filter: blur(16px);
      -webkit-backdrop-filter: blur(16px);
      border-top: 1px solid var(--border-dim);
      padding: 8px 16px;
      justify-content: space-around;
      z-index: 999;
    }

    .mobile-nav a {
      display: flex;
      flex-direction: column;
      align-items: center;
      font-size: 0.7rem;
      color: var(--text-muted);
      gap: 4px;
      padding: 6px 10px;
      border-radius: 20px;
      transition: all 0.2s;
    }

    .mobile-nav a i {
      font-size: 1.2rem;
    }

    .mobile-nav a.active {
      color: var(--deep-space);
      background: var(--glacier-cyan);
      font-weight: 600;
    }

    /* 按钮系统 */
    .btn-primary {
      background: var(--racing-red);
      color: var(--ice-white);
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-size: 1rem;
      box-shadow: 0 4px 14px rgba(230, 57, 70, 0.25);
    }
    .btn-primary:hover {
      background: #C1121F;
      box-shadow: var(--shadow-glow);
      transform: translateY(-1px);
    }

    .btn-outline {
      border: 1px solid var(--glacier-cyan);
      color: var(--glacier-cyan);
      background: transparent;
      padding: 12px 28px;
      border-radius: var(--radius-sm);
    }
    .btn-outline:hover {
      background: var(--glacier-cyan);
      color: var(--deep-space);
    }

    .btn-reverse {
      background: var(--ice-white);
      color: var(--racing-red);
      padding: 14px 36px;
      border-radius: var(--radius-sm);
      font-weight: 700;
    }
    .btn-reverse:hover {
      background: #e0e5dd;
    }

    /* Hero */
    .hero {
      min-height: 100vh;
      display: flex;
      align-items: center;
      position: relative;
      overflow: hidden;
      padding-top: 72px;
    }

    .hero-content {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      gap: 40px;
    }

    .hero-text {
      flex: 0 0 50%;
    }
    .hero-text h1 {
      font-size: 4rem;
      font-weight: 700;
      line-height: 1.15;
      letter-spacing: -0.5px;
      margin-bottom: 24px;
    }
    .hero-text p {
      font-size: 1.15rem;
      color: var(--text-secondary);
      max-width: 480px;
      margin-bottom: 32px;
    }

    .hero-visual {
      flex: 0 0 45%;
      height: 420px;
      position: relative;
    }

    .dynamic-lines {
      width: 100%;
      height: 100%;
      position: relative;
    }
    .line-anim {
      position: absolute;
      background: rgba(168, 218, 220, 0.2);
      border-radius: 2px;
      animation: floatLine 6s infinite alternate ease-in-out;
    }
    @keyframes floatLine {
      0% { transform: translate(0,0) rotate(0deg); opacity: 0.3; }
      100% { transform: translate(15px, -20px) rotate(2deg); opacity: 0.8; }
    }

    .floating-cta {
      position: absolute;
      bottom: 20px;
      right: 20px;
      z-index: 10;
    }

    section {
      padding: var(--space-section) 0;
    }

    .section-title {
      font-size: 2.6rem;
      font-weight: 600;
      margin-bottom: 24px;
      letter-spacing: -0.5px;
    }
    .section-sub {
      color: var(--text-secondary);
      font-size: 1.1rem;
      margin-bottom: 56px;
    }

    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 32px;
    }

    .card {
      background: var(--card-solid);
      border: 1px solid var(--border-dim);
      border-radius: var(--radius-sm);
      padding: 32px 28px;
      transition: all 0.2s ease;
      backdrop-filter: blur(4px);
    }
    .card:hover {
      border-color: var(--glacier-cyan);
      transform: translateY(-4px);
    }
    .card i {
      font-size: 2.2rem;
      color: var(--glacier-cyan);
      margin-bottom: 20px;
    }
    .card h3 {
      font-size: 1.4rem;
      font-weight: 600;
      margin-bottom: 12px;
    }
    .card p {
      color: var(--text-secondary);
      font-size: 0.95rem;
    }

    .alt-row {
      display: flex;
      align-items: center;
      gap: 60px;
      margin-bottom: 80px;
    }
    .alt-row.reverse {
      flex-direction: row-reverse;
    }
    .alt-text {
      flex: 1;
    }
    .alt-img {
      flex: 1;
      border-radius: var(--radius-sm);
      border: 1px solid rgba(255,255,255,0.1);
      overflow: hidden;
    }
    .alt-img img {
      width: 100%;
      height: auto;
      object-fit: cover;
    }

    .stats-grid {
      display: flex;
      justify-content: space-around;
      text-align: center;
    }
    .stat-number {
      font-size: 3.5rem;
      font-weight: 700;
      color: var(--racing-red);
      line-height: 1.2;
    }
    .stat-label {
      color: var(--text-secondary);
      font-size: 1rem;
    }

    .testimonial-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }
    .testimonial-card {
      background: var(--card-bg);
      padding: 36px 28px;
      border-radius: var(--radius-sm);
      position: relative;
    }
    .quote-icon {
      color: var(--glacier-cyan);
      font-size: 2rem;
      opacity: 0.6;
      margin-bottom: 16px;
    }

    .faq-item {
      border-bottom: 1px solid var(--border-dim);
      padding: 20px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      font-weight: 600;
      font-size: 1.1rem;
      cursor: pointer;
      color: var(--ice-white);
      transition: color 0.2s;
    }
    .faq-question:hover {
      color: var(--glacier-cyan);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s;
      color: var(--text-secondary);
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 16px;
    }

    .cta-banner {
      background: var(--racing-red);
      padding: 70px 40px;
      text-align: center;
      border-radius: var(--radius-sm);
    }
    .cta-banner h2 {
      font-size: 2.8rem;
      margin-bottom: 24px;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      padding: 60px 0 40px;
    }
    .footer-col p, .footer-col a {
      color: var(--text-muted);
      font-size: 0.9rem;
      line-height: 2;
    }
    .footer-col a:hover {
      color: var(--glacier-cyan);
    }

    .copyright {
      border-top: 1px solid var(--border-dim);
      padding: 24px 0;
      text-align: center;
      color: var(--text-muted);
      font-size: 0.85rem;
    }

    @media (max-width: 1024px) {
      .hero-content {
        flex-direction: column;
        text-align: center;
      }
      .hero-text { flex: auto; }
      .hero-visual { height: 260px; width: 100%; }
      .grid-3, .testimonial-grid { grid-template-columns: 1fr 1fr; }
    }

    @media (max-width: 768px) {
      .container { padding: 0 20px; }
      .desktop-nav { display: none; }
      .mobile-nav { display: flex; }
      .hero-text h1 { font-size: 2.4rem; }
      .section-title { font-size: 2rem; }
      .grid-3, .testimonial-grid, .stats-grid { grid-template-columns: 1fr; }
      .alt-row, .alt-row.reverse { flex-direction: column; }
      .footer-grid { grid-template-columns: 1fr 1fr; }
      :root { --space-section: 80px; }
    }