/* roulang page: index */
:root {
      --primary: #7B2FFF;
      --primary-glow: rgba(123, 47, 255, 0.6);
      --secondary: #00F0FF;
      --secondary-glow: rgba(0, 240, 255, 0.5);
      --bg-deep: #0A0E1A;
      --bg-card: #1A1F35;
      --text-body: #B0C4DE;
      --text-white: #FFFFFF;
      --border-dim: rgba(123, 47, 255, 0.25);
      --border-active: #00F0FF;
      --radius-lg: 16px;
      --radius-md: 12px;
      --radius-sm: 8px;
      --shadow-card: 0 10px 25px -5px rgba(0,0,0,0.5), 0 4px 10px -6px rgba(0,0,0,0.6);
      --shadow-hover: 0 12px 30px 0 rgba(0, 240, 255, 0.25);
      --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: var(--font-sans);
      background-color: var(--bg-deep);
      color: var(--text-body);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }
    .container {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 1.5rem;
      padding-right: 1.5rem;
    }
    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(248, 250, 252, 0.96);
      backdrop-filter: blur(12px);
      box-shadow: 0 4px 15px rgba(0,0,0,0.08);
      z-index: 50;
      height: 72px;
      display: flex;
      align-items: center;
    }
    .nav-link {
      font-weight: 500;
      color: #1e293b;
      transition: color 0.2s;
      font-size: 0.95rem;
    }
    .nav-link:hover {
      color: var(--secondary);
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      font-weight: 600;
      padding: 0.65rem 1.5rem;
      border-radius: var(--radius-sm);
      transition: all 0.25s;
      box-shadow: 0 4px 12px var(--primary-glow);
      display: inline-block;
      text-align: center;
    }
    .btn-primary:hover {
      background: #8f4fff;
      box-shadow: 0 6px 18px var(--secondary-glow);
      color: white;
    }
    .btn-outline {
      border: 1.5px solid var(--secondary);
      color: var(--secondary);
      font-weight: 600;
      padding: 0.6rem 1.5rem;
      border-radius: var(--radius-sm);
      transition: all 0.25s;
      background: transparent;
      display: inline-block;
      text-align: center;
    }
    .btn-outline:hover {
      background: rgba(0,240,255,0.08);
      box-shadow: 0 0 14px var(--secondary-glow);
    }
    .card {
      background: var(--bg-card);
      border-radius: var(--radius-lg);
      padding: 2rem;
      border: 1px solid var(--border-dim);
      box-shadow: var(--shadow-card);
      transition: transform 0.2s, box-shadow 0.25s, border-color 0.2s;
    }
    .card:hover {
      border-color: var(--border-active);
      box-shadow: var(--shadow-hover);
      transform: translateY(-4px);
    }
    .section-title {
      font-size: 2.25rem;
      font-weight: 700;
      letter-spacing: -0.5px;
      color: white;
      margin-bottom: 0.75rem;
    }
    .section-subtitle {
      color: #9ca3af;
      font-size: 1.125rem;
      max-width: 600px;
      margin-bottom: 2.5rem;
    }
    .gradient-text {
      background: linear-gradient(135deg, #fff 0%, #c0e0ff 100%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }
    .hero-badge {
      background: rgba(0,240,255,0.08);
      border: 1px solid rgba(0,240,255,0.25);
      border-radius: 999px;
      padding: 0.35rem 1rem;
      font-size: 0.9rem;
      color: var(--secondary);
      backdrop-filter: blur(4px);
    }
    .faq-item {
      border-bottom: 1px solid rgba(123,47,255,0.25);
    }
    .faq-question {
      cursor: pointer;
      padding: 1.25rem 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      color: white;
      font-size: 1.15rem;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease, padding 0.2s;
      color: #b0c4de;
      padding-right: 1.5rem;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 1.25rem;
    }
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
      color: var(--secondary);
    }
    .faq-icon {
      font-size: 1.5rem;
      font-weight: 300;
      transition: 0.3s;
    }
    @media (max-width: 768px) {
      .section-title {
        font-size: 1.8rem;
      }
      .header {
        height: 64px;
      }
    }