/* roulang page: index */
:root {
      --primary-dark: #1A1D2E;
      --accent-cyan: #00E5FF;
      --accent-red: #FF4655;
      --bg-light: #F4F6FA;
      --white: #FFFFFF;
      --text-dark: #1A1D2E;
      --text-mid: #5A6070;
      --text-weak: #8E94A4;
      --text-light-bg: #B0B8CC;
      --border-light: #E2E6EE;
      --card-shadow: 0 2px 12px rgba(26,29,46,0.06);
      --card-shadow-hover: 0 8px 28px rgba(26,29,46,0.12);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 6px;
      --transition-smooth: all 0.25s cubic-bezier(0.25, 0.46, 0.45, 0.94);
    }
    * {
      box-sizing: border-box;
    }
    body {
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Segoe UI', sans-serif;
      margin: 0;
      background-color: var(--white);
      color: var(--text-dark);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    h1, h2, h3, h4 {
      font-family: 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      margin: 0;
    }
    h1 {
      font-size: 48px;
      line-height: 1.15;
      font-weight: 800;
      letter-spacing: -0.5px;
    }
    h2 {
      font-size: 36px;
      line-height: 1.2;
      font-weight: 700;
      letter-spacing: -0.3px;
      margin-bottom: 1rem;
    }
    h3 {
      font-size: 24px;
      line-height: 1.35;
      font-weight: 600;
    }
    h4 {
      font-size: 18px;
      line-height: 1.4;
      font-weight: 600;
    }
    .text-body {
      font-size: 16px;
      line-height: 1.7;
      font-weight: 400;
      color: var(--text-mid);
    }
    .text-small {
      font-size: 14px;
      line-height: 1.5;
      font-weight: 500;
    }
    .container {
      max-width: 1200px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 40px;
      padding-right: 40px;
    }
    @media (max-width: 768px) {
      .container {
        padding-left: 5vw;
        padding-right: 5vw;
      }
      h1 {
        font-size: 32px;
      }
      h2 {
        font-size: 28px;
      }
      h3 {
        font-size: 20px;
      }
      .card-hover:hover {
        transform: none !important;
        box-shadow: var(--card-shadow) !important;
      }
    }
    .btn-primary {
      background-color: var(--accent-cyan);
      color: var(--primary-dark);
      font-weight: 600;
      border-radius: var(--radius-btn);
      padding: 0.875rem 2rem;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      transition: var(--transition-smooth);
      border: none;
      cursor: pointer;
      letter-spacing: 0.5px;
    }
    .btn-primary:hover {
      background-color: #00C8E0;
      box-shadow: 0 8px 20px rgba(0,229,255,0.3);
    }
    .btn-secondary {
      background: transparent;
      border: 2px solid var(--accent-cyan);
      color: var(--accent-cyan);
      font-weight: 600;
      border-radius: var(--radius-btn);
      padding: 0.75rem 2rem;
      display: inline-flex;
      align-items: center;
      gap: 0.5rem;
      transition: var(--transition-smooth);
      cursor: pointer;
    }
    .btn-secondary:hover {
      background: rgba(0,229,255,0.08);
    }
    .btn-accent {
      background-color: var(--accent-red);
      color: white;
      font-weight: 600;
      border-radius: var(--radius-btn);
      padding: 0.875rem 2rem;
      transition: var(--transition-smooth);
      border: none;
      cursor: pointer;
    }
    .btn-accent:hover {
      background-color: #E63946;
    }
    .card {
      background: var(--white);
      border-radius: var(--radius-card);
      box-shadow: var(--card-shadow);
      transition: var(--transition-smooth);
      overflow: hidden;
    }
    .card-hover:hover {
      transform: translateY(-4px);
      box-shadow: var(--card-shadow-hover);
    }
    .nav-channel-link {
      position: relative;
      transition: color 0.2s;
    }
    .nav-channel-link.active::after {
      content: '';
      position: absolute;
      bottom: -2px;
      left: 0;
      width: 100%;
      height: 3px;
      background-color: var(--accent-cyan);
    }
    details summary {
      list-style: none;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 1rem 0;
      border-bottom: 1px solid var(--border-light);
      font-weight: 600;
    }
    details summary::-webkit-details-marker {
      display: none;
    }
    details[open] summary i {
      transform: rotate(45deg);
    }
    details summary i {
      transition: transform 0.3s;
      color: var(--accent-cyan);
    }
    .faq-content {
      padding: 0 0 1rem;
      color: var(--text-mid);
    }
    .glow-bg {
      background: radial-gradient(circle at 70% 30%, rgba(0,229,255,0.25) 0%, rgba(26,29,46,0) 70%);
    }