/* roulang page: index */
/* 设计变量与基础重置 */
    :root {
      --bg-deep: #0B0E14;
      --bg-card: rgba(255,255,255,0.03);
      --accent-cyan: #00F0A8;
      --accent-magenta: #FF3C5A;
      --text-primary: #F0F2F5;
      --text-secondary: #9AA0B0;
      --border-dim: rgba(0,240,168,0.12);
      --border-light: rgba(255,255,255,0.08);
      --shadow-glow: 0 0 20px rgba(0,240,168,0.08);
      --shadow-glow-hover: 0 0 40px rgba(0,240,168,0.25);
      --font-mono: 'JetBrains Mono', 'SF Mono', 'Menlo', monospace;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --radius-pill: 20px;
      --transition-smooth: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Inter', system-ui, -apple-system, sans-serif;
      background-color: var(--bg-deep);
      color: var(--text-primary);
      line-height: 1.75;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }

    /* 自定义滚动条 */
    ::-webkit-scrollbar {
      width: 6px;
    }
    ::-webkit-scrollbar-track {
      background: #0B0E14;
    }
    ::-webkit-scrollbar-thumb {
      background: #2A303C;
      border-radius: 12px;
    }

    /* 背景网格线动态氛围 */
    .bg-grid {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background-image: 
        linear-gradient(rgba(0,240,168,0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(0,240,168,0.03) 1px, transparent 1px);
      background-size: 40px 40px;
      pointer-events: none;
      z-index: 0;
    }

    .container-main {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
      position: relative;
      z-index: 2;
    }

    /* 导航桌面 */
    .nav-desktop {
      backdrop-filter: blur(16px);
      background: rgba(11,14,20,0.85);
      border-bottom: 1px solid rgba(255,255,255,0.06);
    }
    .nav-link {
      position: relative;
      transition: color var(--transition-smooth);
    }
    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--accent-cyan);
      transition: width var(--transition-smooth);
    }
    .nav-link:hover::after,
    .nav-link.active::after {
      width: 100%;
    }
    .nav-link.active {
      color: var(--accent-cyan);
    }

    /* 移动端底部Tab */
    .mobile-tab-bar {
      background: rgba(11,14,20,0.96);
      border-top: 1px solid rgba(255,255,255,0.06);
      backdrop-filter: blur(20px);
    }
    .tab-item.active i,
    .tab-item.active span {
      color: var(--accent-cyan);
    }

    /* 数字跳动字体 */
    .counter-digit {
      font-family: var(--font-mono);
      font-weight: 700;
    }

    /* 卡片通用 */
    .card-glass {
      background: var(--bg-card);
      border: 1px solid var(--border-dim);
      border-radius: var(--radius-card);
      backdrop-filter: blur(8px);
      transition: transform 0.3s ease-out, box-shadow 0.3s, border-color 0.3s;
      box-shadow: var(--shadow-glow);
    }
    .card-glass:hover {
      transform: translateY(-6px);
      border-color: var(--accent-cyan);
      box-shadow: var(--shadow-glow-hover);
    }

    /* 按钮 */
    .btn-primary {
      background: var(--accent-cyan);
      color: #0B0E14;
      font-weight: 600;
      border-radius: var(--radius-btn);
      transition: all var(--transition-smooth);
      box-shadow: 0 0 12px rgba(0,240,168,0.3);
    }
    .btn-primary:hover {
      background: #33F5BC;
      box-shadow: 0 0 28px rgba(0,240,168,0.55);
    }
    .btn-outline {
      border: 1px solid rgba(255,255,255,0.25);
      color: #E0E4EB;
      border-radius: var(--radius-btn);
      transition: all var(--transition-smooth);
    }
    .btn-outline:hover {
      border-color: var(--accent-cyan);
      color: var(--accent-cyan);
      background: rgba(0,240,168,0.05);
    }

    /* FAQ 手风琴 */
    .faq-question {
      cursor: pointer;
      transition: color 0.2s;
    }
    .faq-question:hover {
      color: var(--accent-cyan);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      opacity: 0;
      transition: max-height 0.4s ease, opacity 0.3s, padding 0.3s;
      background: rgba(255,255,255,0.02);
      border-radius: 8px;
      color: var(--text-secondary);
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      opacity: 1;
      padding: 16px;
      margin-top: 8px;
    }
    .faq-icon {
      transition: transform 0.3s;
    }
    .faq-item.open .faq-icon {
      transform: rotate(45deg);
    }

    /* 对比区块 */
    .vs-divider {
      background: var(--accent-magenta);
      width: 2px;
      height: 60px;
      margin: 0 auto;
    }
    .compare-bad {
      color: var(--accent-magenta);
    }
    .compare-good {
      color: var(--accent-cyan);
    }

    /* 段落间距 */
    p {
      margin-bottom: 1.5em;
    }

    @media (max-width: 767px) {
      .container-main {
        padding: 0 16px;
      }
      .mobile-tab-bar {
        display: flex;
      }
      .nav-desktop {
        display: none;
      }
      h1 {
        font-size: 2.2rem;
        line-height: 1.2;
      }
    }
    @media (min-width: 768px) {
      .mobile-tab-bar {
        display: none;
      }
      .nav-desktop {
        display: flex;
      }
      h1 {
        font-size: 3.4rem;
      }
    }