/* roulang page: index */
:root {
      --primary-deep: #0B0F19;
      --accent-cyan: #00F0FF;
      --accent-orange: #FF4D00;
      --card-bg: rgba(255, 255, 255, 0.03);
      --card-border: rgba(255, 255, 255, 0.06);
      --text-primary: #FFFFFF;
      --text-secondary: rgba(255, 255, 255, 0.7);
      --text-tertiary: rgba(255, 255, 255, 0.4);
      --font-mono: 'JetBrains Mono', 'SF Mono', 'Cascadia Code', monospace;
      --border-radius-lg: 16px;
      --border-radius-pill: 50px;
      --transition-smooth: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
      --glass-blur: blur(12px);
    }

    * {
      box-sizing: border-box;
    }

    body {
      background-color: var(--primary-deep);
      color: var(--text-primary);
      font-family: 'Inter', 'SF Pro Text', -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', sans-serif;
      line-height: 1.7;
      margin: 0;
      overflow-x: hidden;
    }

    h1, h2, h3, h4, h5 {
      font-weight: 700;
      letter-spacing: -0.02em;
      color: var(--text-primary);
    }

    h1 {
      font-size: 3.5rem;
    }

    h2 {
      font-size: 2.5rem;
      margin-bottom: 1.5rem;
    }

    .text-mono {
      font-family: var(--font-mono);
      font-weight: 600;
      color: var(--accent-cyan);
    }

    .text-cyan {
      color: var(--accent-cyan);
    }

    .text-orange {
      color: var(--accent-orange);
    }

    .bg-glass {
      background: var(--card-bg);
      backdrop-filter: var(--glass-blur);
      border: 1px solid var(--card-border);
      border-radius: var(--border-radius-lg);
    }

    .btn-primary-cyan {
      background: radial-gradient(circle at center, #00F0FF, #0088CC);
      color: var(--primary-deep);
      border: none;
      border-radius: var(--border-radius-pill);
      padding: 0.75rem 2rem;
      font-weight: 600;
      transition: var(--transition-smooth);
      box-shadow: 0 0 15px rgba(0, 240, 255, 0.2);
    }

    .btn-primary-cyan:hover {
      box-shadow: 0 0 25px rgba(0, 240, 255, 0.6);
      transform: scale(1.02);
      color: var(--primary-deep);
    }

    .btn-outline-cyan {
      background: transparent;
      color: var(--accent-cyan);
      border: 1px solid var(--accent-cyan);
      border-radius: var(--border-radius-pill);
      padding: 0.75rem 2rem;
      font-weight: 600;
      transition: var(--transition-smooth);
    }

    .btn-outline-cyan:hover {
      background: rgba(0, 240, 255, 0.1);
      color: var(--accent-cyan);
      border-color: var(--accent-cyan);
    }

    .navbar {
      background: rgba(11, 15, 25, 0.8);
      backdrop-filter: blur(15px);
      border-bottom: 1px solid rgba(255, 255, 255, 0.05);
    }

    .navbar-brand {
      font-weight: 700;
      font-size: 1.8rem;
      color: var(--accent-cyan) !important;
      letter-spacing: -0.5px;
    }

    .nav-pills .nav-link {
      color: var(--text-secondary);
      border-radius: 50px;
      padding: 0.5rem 1.25rem;
      font-weight: 500;
      transition: var(--transition-smooth);
      white-space: nowrap;
    }

    .nav-pills .nav-link:hover, .nav-pills .nav-link.active {
      background: rgba(255, 255, 255, 0.08);
      color: #fff;
    }

    .search-icon {
      color: var(--text-secondary);
      font-size: 1.4rem;
      cursor: pointer;
      transition: var(--transition-smooth);
    }

    .search-icon:hover {
      color: var(--accent-cyan);
    }

    .hero-visual {
      width: 100%;
      height: 400px;
      background: radial-gradient(circle at 30% 30%, rgba(0,240,255,0.15), transparent 70%);
      position: relative;
      border-radius: var(--border-radius-lg);
      overflow: hidden;
    }

    .hero-visual img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      opacity: 0.8;
    }

    .card-custom {
      background: var(--card-bg);
      backdrop-filter: var(--glass-blur);
      border: 1px solid var(--card-border);
      border-radius: var(--border-radius-lg);
      transition: var(--transition-smooth);
      height: 100%;
    }

    .card-custom:hover {
      background: rgba(255, 255, 255, 0.06);
      border-color: rgba(0, 240, 255, 0.2);
      transform: translateY(-4px);
      box-shadow: 0 4px 30px rgba(0, 0, 0, 0.5);
    }

    .bento-card {
      background: var(--card-bg);
      backdrop-filter: var(--glass-blur);
      border: 1px solid var(--card-border);
      border-radius: var(--border-radius-lg);
      transition: var(--transition-smooth);
      overflow: hidden;
    }

    .bento-card:hover {
      background: rgba(255, 255, 255, 0.06);
      border-color: rgba(0, 240, 255, 0.2);
    }

    .faq-accordion .accordion-button {
      background: transparent;
      color: var(--text-primary);
      font-weight: 600;
      border: none;
      padding: 1.2rem 0;
      font-size: 1.1rem;
    }

    .faq-accordion .accordion-button:not(.collapsed) {
      background: transparent;
      color: var(--accent-cyan);
      box-shadow: none;
    }

    .faq-accordion .accordion-button::after {
      filter: brightness(0) invert(1);
    }

    .faq-accordion .accordion-body {
      color: var(--text-secondary);
      padding: 0 0 1.2rem 0;
    }

    .footer a {
      color: var(--text-tertiary);
      text-decoration: none;
      transition: var(--transition-smooth);
    }

    .footer a:hover {
      color: var(--accent-cyan);
    }

    @media (max-width: 992px) {
      h1 {
        font-size: 2.8rem;
      }
      h2 {
        font-size: 2rem;
      }
    }

    @media (max-width: 768px) {
      h1 {
        font-size: 2.2rem;
      }
      .navbar .nav-pills {
        flex-wrap: nowrap;
        overflow-x: auto;
        padding-bottom: 0.5rem;
      }
      .hero-visual {
        height: 280px;
        margin-top: 2rem;
      }
      .bento-grid {
        grid-template-columns: 1fr;
      }
    }

    @media (max-width: 576px) {
      .btn-primary-cyan, .btn-outline-cyan {
        padding: 0.6rem 1.5rem;
        font-size: 0.9rem;
      }
    }