/* roulang page: index */
:root {
      --neon-cyan: #00F0FF;
      --neon-pink: #FF3CAC;
      --surface-dark: #141B23;
      --border-dim: #1C2530;
      --text-primary: #FFFFFF;
      --text-body: #B0C4DE;
      --text-muted: #6B7B8D;
      --bg-deep: #0A0E17;
      --radius-card: 16px;
      --shadow-card: 0 20px 40px rgba(0,0,0,0.6);
    }
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: "Inter", "PingFang SC", "Microsoft YaHei", "SF Pro Display", sans-serif;
      background-color: var(--bg-deep);
      color: var(--text-body);
      line-height: 1.8;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    h1, h2, h3, h4 {
      color: var(--text-primary);
      font-weight: 700;
      letter-spacing: -0.02em;
    }
    h1 {
      font-size: 56px;
      line-height: 1.2;
      font-weight: 800;
    }
    h2 {
      font-size: 40px;
      line-height: 1.3;
    }
    h3 {
      font-size: 24px;
      font-weight: 600;
      line-height: 1.4;
    }
    @media (max-width: 768px) {
      h1 { font-size: 36px; }
      h2 { font-size: 28px; }
      h3 { font-size: 22px; }
      body { font-size: 15px; }
    }
    .container-main {
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 24px;
      padding-right: 24px;
    }
    .section-spacing {
      padding-top: 100px;
      padding-bottom: 100px;
    }
    @media (max-width: 768px) {
      .section-spacing {
        padding-top: 64px;
        padding-bottom: 64px;
      }
    }
    /* 卡片基础 */
    .card-dark {
      background-color: var(--surface-dark);
      border: 1px solid rgba(0,240,255,0.15);
      border-radius: var(--radius-card);
      padding: 32px;
      transition: all 0.3s ease;
      box-shadow: var(--shadow-card);
    }
    .card-dark:hover {
      border-color: var(--neon-cyan);
      transform: translateY(-4px);
      box-shadow: 0 24px 48px rgba(0,240,255,0.15);
    }
    /* 按钮 */
    .btn-primary {
      background: linear-gradient(135deg, #00F0FF, #0088CC);
      color: #0A0E17;
      font-weight: 700;
      border-radius: 50px;
      padding: 14px 40px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      transition: all 0.25s ease;
      border: none;
      cursor: pointer;
      letter-spacing: 0.5px;
      box-shadow: 0 8px 18px rgba(0,240,255,0.3);
    }
    .btn-primary:hover {
      background: linear-gradient(135deg, #2BF5FF, #00A6E0);
      box-shadow: 0 0 24px rgba(0,240,255,0.7);
      transform: scale(1.02);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--neon-cyan);
      color: var(--neon-cyan);
      font-weight: 600;
      border-radius: 50px;
      padding: 14px 40px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      transition: all 0.25s ease;
      cursor: pointer;
    }
    .btn-outline:hover {
      background: rgba(0,240,255,0.12);
      box-shadow: 0 0 20px rgba(0,240,255,0.5);
    }
    /* 导航 */
    .nav-glow {
      border-bottom: 1px solid var(--neon-cyan);
      background-color: rgba(10,14,23,0.92);
      backdrop-filter: blur(12px);
    }
    .nav-link {
      color: var(--text-body);
      transition: 0.2s;
      font-weight: 500;
      position: relative;
    }
    .nav-link:hover, .nav-link.active {
      color: var(--neon-cyan);
      text-shadow: 0 0 8px rgba(0,240,255,0.6);
    }
    .nav-link.active::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 100%;
      height: 2px;
      background: var(--neon-cyan);
      box-shadow: 0 0 12px var(--neon-cyan);
    }
    /* FAQ 手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border-dim);
    }
    .faq-question {
      cursor: pointer;
      transition: color 0.2s;
    }
    .faq-question:hover {
      color: var(--neon-cyan);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.4s ease;
    }
    .faq-item.open .faq-answer {
      max-height: 300px;
    }
    .faq-item.open .faq-question {
      color: var(--neon-cyan);
    }
    /* 移动端汉堡菜单 */
    .mobile-menu {
      background: rgba(10,14,23,0.96);
      backdrop-filter: blur(20px);
    }
    @media (min-width: 769px) {
      .mobile-menu { display: none; }
    }