/* roulang page: index */
/* 设计变量与全局样式 */
    :root {
      --primary: #1DD15E;    /* 电光绿 */
      --primary-dark: #17b84d;
      --secondary: #0F1A2E;  /* 深墨蓝 */
      --accent: #F77F2E;     /* 暖橙 */
      --accent-dark: #e06a1c;
      --bg-light: #F9FAFB;
      --card-white: #FFFFFF;
      --text-gray: #4B5563;
      --border-light: #E5E7EB;
      --radius-lg: 12px;
      --radius-md: 8px;
      --shadow-sm: 0 2px 8px rgba(0,0,0,0.04), 0 4px 16px rgba(0,0,0,0.06);
      --shadow-hover: 0 8px 24px rgba(0,0,0,0.12);
      --font-mono: 'Roboto Mono', 'Courier New', monospace;
    }

    * {
      box-sizing: border-box;
    }

    body {
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      margin: 0;
      background-color: var(--bg-light);
      color: #1F2937;
      line-height: 1.7;
      -webkit-font-smoothing: antialiased;
    }

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

    /* 导航栏固定顶部 */
    .navbar {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 64px;
      background: rgba(15, 26, 46, 0.85);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      display: flex;
      align-items: center;
      z-index: 1000;
      border-bottom: 1px solid rgba(255,255,255,0.08);
      transition: background 0.3s ease;
    }
    .navbar.scrolled {
      background: rgba(15, 26, 46, 1);
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
    }
    .logo-area {
      display: flex;
      align-items: baseline;
      gap: 8px;
      color: white;
    }
    .logo-text {
      font-size: 1.5rem;
      font-weight: 700;
      letter-spacing: 1px;
      color: var(--primary);
      line-height: 1;
    }
    .logo-domain {
      font-size: 0.75rem;
      color: rgba(255,255,255,0.65);
      font-weight: 400;
    }
    .nav-links {
      display: flex;
      gap: 28px;
      align-items: center;
    }
    .nav-links a {
      color: white;
      text-decoration: none;
      font-weight: 500;
      font-size: 0.95rem;
      position: relative;
      padding: 8px 0;
      transition: color 0.2s;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 50%;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width 0.25s ease, left 0.25s ease;
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .nav-links a:hover::after {
      width: 100%;
      left: 0;
    }
    .btn-cta-nav {
      background: var(--accent);
      color: white;
      padding: 10px 22px;
      border-radius: 40px;
      font-weight: 600;
      font-size: 0.9rem;
      transition: background 0.2s, transform 0.1s;
      text-decoration: none;
      display: inline-block;
      border: none;
      cursor: pointer;
      white-space: nowrap;
    }
    .btn-cta-nav:hover {
      background: var(--accent-dark);
      transform: scale(1.02);
    }
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: transparent;
      border: none;
      padding: 8px;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: white;
      border-radius: 4px;
      transition: 0.3s;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 64px;
      left: 0;
      width: 100%;
      background: #0F1A2E;
      flex-direction: column;
      padding: 24px;
      gap: 20px;
      z-index: 999;
      border-top: 1px solid rgba(255,255,255,0.1);
    }
    .mobile-menu a {
      color: white;
      font-size: 1.2rem;
      text-decoration: none;
      font-weight: 500;
    }
    .mobile-menu .btn-cta-nav {
      display: inline-block;
      width: fit-content;
      margin-top: 8px;
    }

    /* 按钮系统 */
    .btn-primary {
      background: var(--primary);
      color: #0F1A2E;
      font-weight: 600;
      padding: 12px 28px;
      border-radius: var(--radius-md);
      text-decoration: none;
      display: inline-block;
      transition: filter 0.2s, transform 0.2s;
      border: none;
      cursor: pointer;
    }
    .btn-primary:hover {
      filter: brightness(1.1);
      transform: scale(1.02);
    }
    .btn-secondary {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      font-weight: 600;
      padding: 12px 28px;
      border-radius: var(--radius-md);
      text-decoration: none;
      display: inline-block;
      transition: background 0.2s, transform 0.2s;
    }
    .btn-secondary:hover {
      background: rgba(29,209,94,0.1);
      transform: scale(1.02);
    }
    .btn-accent-lg {
      background: var(--accent);
      color: white;
      font-weight: 700;
      font-size: 1.125rem;
      padding: 14px 32px;
      border-radius: var(--radius-md);
      text-decoration: none;
      display: inline-block;
      transition: background 0.2s;
      border: none;
      cursor: pointer;
    }
    .btn-accent-lg:hover {
      background: #e06a1c;
    }

    /* 卡片样式 */
    .card {
      background: var(--card-white);
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-sm);
      padding: 24px;
      transition: transform 0.2s, box-shadow 0.3s;
    }
    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }

    /* 数据大数字 */
    .data-number {
      font-family: var(--font-mono);
      font-weight: 700;
      font-size: 2.8rem;
      color: var(--primary);
      line-height: 1.2;
    }
    .data-accent {
      color: var(--accent);
    }

    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 16px 0;
      cursor: pointer;
    }
    .faq-question {
      font-weight: 600;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease, padding 0.35s ease;
      background: #F9FAFB;
      border-radius: 8px;
      margin-top: 0;
      padding: 0 16px;
      color: var(--text-gray);
      line-height: 1.7;
    }
    .faq-item.active .faq-answer {
      max-height: 300px;
      padding: 16px;
      margin-top: 12px;
    }

    /* Hero背景纹理 (CSS生成替代图片) */
    .hero-bg {
      background: radial-gradient(circle at 30% 40%, #1a2c4a 0%, #0F1A2E 80%);
      position: relative;
      overflow: hidden;
    }
    .hero-bg::before {
      content: "";
      position: absolute;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 400 400" opacity="0.08"><path d="M50 150 L150 50 L250 150 L350 100 L300 200 L200 300 L100 250 Z" fill="none" stroke="%231DD15E" stroke-width="2"/><circle cx="80" cy="320" r="30" fill="none" stroke="%231DD15E" stroke-width="1.5"/></svg>');
      background-size: cover;
      pointer-events: none;
    }

    /* 响应式 */
    @media (max-width: 1024px) {
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .mobile-menu.show { display: flex; }
    }
    @media (max-width: 768px) {
      .container { padding: 0 16px; }
      .data-number { font-size: 2.2rem; }
    }