/* roulang page: index */
:root {
      --red: #D40000;
      --red-hover: #E50000;
      --black: #1A1A1A;
      --gray-bg: #F5F5F5;
      --white: #FFFFFF;
      --gold: #C5A572;
      --text-primary: #1A1A1A;
      --text-secondary: #4A4A4A;
      --text-light: #FFFFFF;
      --border-light: #E5E5E5;
      --shadow-sm: 0 4px 12px rgba(0,0,0,0.04);
      --shadow-md: 0 12px 28px rgba(0,0,0,0.08);
      --shadow-lg: 0 24px 48px rgba(0,0,0,0.12);
      --radius-sm: 12px;
      --radius-md: 16px;
      --radius-lg: 24px;
      --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
      --font-sans: 'Inter', 'PingFang SC', 'Microsoft YaHei', system-ui, -apple-system, sans-serif;
      --max-width: 1280px;
      --nav-height: 64px;
    }

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

    html {
      scroll-behavior: smooth;
      -webkit-font-smoothing: antialiased;
    }

    body {
      font-family: var(--font-sans);
      font-size: 16px;
      line-height: 1.7;
      color: var(--text-primary);
      background-color: var(--white);
      overflow-x: hidden;
    }

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

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

    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 32px;
      width: 100%;
    }

    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--nav-height);
      z-index: 1000;
      transition: background var(--transition), box-shadow var(--transition);
      background: transparent;
      backdrop-filter: blur(8px);
    }

    .header.scrolled {
      background: rgba(255,255,255,0.96);
      box-shadow: 0 2px 16px rgba(0,0,0,0.06);
      backdrop-filter: blur(20px);
    }

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

    .logo {
      font-weight: 700;
      font-size: 1.5rem;
      letter-spacing: -0.5px;
      color: var(--white);
      transition: color var(--transition);
      white-space: nowrap;
    }

    .header.scrolled .logo {
      color: var(--black);
    }

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

    .nav-links a {
      font-weight: 500;
      font-size: 0.95rem;
      position: relative;
      padding: 4px 0;
      color: rgba(255,255,255,0.9);
      transition: color var(--transition);
    }

    .header.scrolled .nav-links a {
      color: var(--text-primary);
    }

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

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

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
      padding: 8px;
      z-index: 1001;
    }

    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--white);
      transition: all var(--transition);
      display: block;
    }

    .header.scrolled .hamburger span {
      background: var(--black);
    }

    /* Hero */
    .hero {
      min-height: 100vh;
      background: linear-gradient(135deg, #1A1A1A 0%, #2A2020 100%);
      display: flex;
      align-items: center;
      position: relative;
      overflow: hidden;
      padding-top: var(--nav-height);
    }

    .hero::before {
      content: '';
      position: absolute;
      top: -20%;
      right: -10%;
      width: 70%;
      height: 120%;
      background: radial-gradient(circle at center, rgba(212,0,0,0.25) 0%, transparent 70%);
      pointer-events: none;
    }

    .hero .container {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 60px;
      align-items: center;
      position: relative;
      z-index: 2;
    }

    .hero-content h1 {
      font-size: 3.5rem;
      font-weight: 700;
      line-height: 1.2;
      color: var(--white);
      margin-bottom: 20px;
      letter-spacing: -1px;
    }

    .hero-content .subtitle {
      font-size: 1.25rem;
      color: rgba(255,255,255,0.8);
      margin-bottom: 36px;
      max-width: 450px;
    }

    .cta-group {
      display: flex;
      flex-wrap: wrap;
      gap: 16px;
    }

    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 14px 32px;
      border-radius: 40px;
      font-weight: 600;
      font-size: 1rem;
      transition: all var(--transition);
      border: 2px solid transparent;
      cursor: pointer;
      white-space: nowrap;
    }

    .btn-primary {
      background: var(--red);
      color: var(--white);
      border-color: var(--red);
    }

    .btn-primary:hover {
      background: var(--red-hover);
      border-color: var(--red-hover);
      transform: translateY(-2px);
      box-shadow: 0 8px 20px rgba(212,0,0,0.4);
    }

    .btn-outline {
      background: transparent;
      color: var(--white);
      border-color: rgba(255,255,255,0.6);
    }

    .btn-outline:hover {
      background: var(--white);
      color: var(--black);
      border-color: var(--white);
      transform: translateY(-2px);
    }

    .hero-device {
      position: relative;
      display: flex;
      justify-content: center;
      transform: perspective(800px) rotateY(-4deg) rotateX(2deg);
      transition: transform 0.1s ease-out;
    }

    .hero-device img {
      width: 100%;
      max-width: 320px;
      border-radius: 32px;
      box-shadow: 0 32px 64px rgba(0,0,0,0.5);
      border: 2px solid rgba(255,255,255,0.15);
    }

    /* 通用板块 */
    section {
      padding: 100px 0;
    }

    .section-title {
      font-size: 2.5rem;
      font-weight: 700;
      margin-bottom: 16px;
      letter-spacing: -0.5px;
    }

    .section-desc {
      font-size: 1.125rem;
      color: var(--text-secondary);
      max-width: 600px;
      margin-bottom: 48px;
    }

    .bg-gray {
      background: #FAFAFA;
    }

    /* 优势 非对称布局 */
    .advantages-grid {
      display: grid;
      grid-template-columns: 1.2fr 0.8fr;
      gap: 24px;
    }

    .adv-card {
      background: var(--white);
      border-radius: var(--radius-md);
      padding: 32px;
      box-shadow: var(--shadow-sm);
      transition: all var(--transition);
      display: flex;
      flex-direction: column;
      height: fit-content;
    }

    .adv-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-lg);
    }

    .adv-card.large {
      grid-row: span 2;
      padding: 40px;
    }

    .adv-card.large .adv-image {
      margin-top: 24px;
      border-radius: var(--radius-sm);
      overflow: hidden;
    }

    .adv-card.stacked {
      display: flex;
      flex-direction: row;
      align-items: center;
      gap: 24px;
    }

    .adv-icon {
      font-size: 2rem;
      color: var(--red);
      margin-bottom: 8px;
    }

    .adv-card h3 {
      font-size: 1.5rem;
      font-weight: 600;
      margin-bottom: 12px;
    }

    .adv-card p {
      color: var(--text-secondary);
      line-height: 1.6;
    }

    /* 产品体验 */
    .experience-showcase {
      display: flex;
      justify-content: center;
      align-items: center;
      gap: 24px;
      flex-wrap: wrap;
      position: relative;
    }

    .device-frame {
      background: #E8E8E8;
      border-radius: 28px;
      padding: 12px;
      box-shadow: var(--shadow-md);
      transition: transform var(--transition);
    }

    .device-frame img {
      border-radius: 20px;
      width: 240px;
    }

    .device-frame:nth-child(1) { transform: rotate(-3deg); }
    .device-frame:nth-child(2) { transform: translateY(-20px); z-index: 2; }
    .device-frame:nth-child(3) { transform: rotate(3deg); }

    /* 数据 */
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 40px;
      text-align: center;
    }

    .stat-number {
      font-size: 3rem;
      font-weight: 700;
      color: var(--gold);
      line-height: 1.2;
    }

    .stat-label {
      font-size: 1.1rem;
      color: var(--text-secondary);
      margin-top: 8px;
    }

    /* 下载CTA */
    .cta-band {
      background: var(--red);
      padding: 80px 0;
      text-align: center;
    }

    .cta-band h2 {
      color: var(--white);
      font-size: 2.5rem;
      margin-bottom: 24px;
    }

    .btn-white {
      background: var(--white);
      color: var(--red);
      border-color: var(--white);
      font-weight: 700;
    }

    .btn-white:hover {
      background: var(--red);
      color: var(--white);
      border-color: var(--white);
    }

    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }

    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }

    .faq-question {
      width: 100%;
      background: transparent;
      border: none;
      padding: 24px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 1.125rem;
      font-weight: 600;
      cursor: pointer;
      text-align: left;
      color: var(--text-primary);
    }

    .faq-icon {
      font-size: 1.5rem;
      color: var(--red);
      transition: transform var(--transition);
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
      color: var(--text-secondary);
      padding: 0 0;
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 24px;
    }

    .faq-item.active .faq-icon {
      transform: rotate(45deg);
    }

    /* 页脚 */
    .footer {
      background: var(--black);
      color: rgba(255,255,255,0.7);
      padding: 32px 0;
      text-align: center;
      font-size: 0.9rem;
    }

    /* 响应式 */
    @media (max-width: 1024px) {
      .hero .container {
        grid-template-columns: 1fr;
        text-align: center;
        gap: 40px;
      }
      .hero-content .subtitle { margin-left: auto; margin-right: auto; }
      .cta-group { justify-content: center; }
      .advantages-grid {
        grid-template-columns: 1fr;
      }
      .adv-card.stacked {
        flex-direction: column;
        align-items: flex-start;
      }
    }

    @media (max-width: 768px) {
      .container { padding: 0 20px; }
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .hero-content h1 { font-size: 2.4rem; }
      section { padding: 60px 0; }
      .stats-grid { grid-template-columns: 1fr; gap: 32px; }
      .experience-showcase { flex-direction: column; }
      .device-frame img { width: 200px; }
    }

    .mobile-menu {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100vh;
      background: rgba(0,0,0,0.95);
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      gap: 32px;
      z-index: 999;
      transform: translateX(100%);
      transition: transform 0.4s ease;
    }

    .mobile-menu.open {
      transform: translateX(0);
    }

    .mobile-menu a {
      color: white;
      font-size: 1.5rem;
      font-weight: 500;
    }