.timeline {
      margin-top: 2rem;
      border-left: 3px solid #343a40;
      padding-left: 2rem;
      position: relative;
      overflow: hidden;
    }

    .timeline::before {
      content: "";
      position: absolute;
      top: 0;
      left: 0;
      height: 100%;
      width: 3px;
      background: #343a40;
      animation: drawLine 2s ease forwards;
    }

    @keyframes drawLine {
      from { height: 0; }
      to { height: 100%; }
    }

    .timeline-item {
      margin-bottom: 2rem;
      position: relative;
    }

    .timeline-item::before {
      content: "";
      position: absolute;
      left: -1.25rem;
      top: 0.45rem;
      width: 12px;
      height: 12px;
      background-color: #343a40;
      border-radius: 50%;
    }

    .timeline-year {
      font-weight: bold;
      font-size: 1.2rem;
      margin-bottom: 0.1rem;
      color: #212529;
    }

    .timeline-content {
      color: #495057;
      display: flex;
      flex-direction: column;
      gap: 0.25rem;
    }

    .timeline-content-header {
      display: flex;
      align-items: center;
      gap: 0.5rem;
      cursor: pointer;
      padding-left: 0.25rem;
      transition: background-color 0.3s;
    }

    .timeline-content-header:hover {
      background-color: rgba(0, 0, 0, 0.05);
      border-radius: 4px;
    }

    .timeline-content img {
      width: 24px;
      height: 24px;
      object-fit: contain;
    }

    .dropdown-arrow {
      font-size: 1rem;
      color: #495057;
    }

    .timeline-description {
      font-size: 0.95rem;
      line-height: 1.5;
      padding-left: 1.75rem;
      display: none;
    }

    .timeline-description.open {
      display: block;
    }

    .expertise-card {
      text-decoration: none;
      color: inherit;
      background-color: #f1f3f5;
      padding: 2rem;
      border-radius: 1rem;
      transition: transform 0.3s ease, box-shadow 0.3s ease;
    }

    .expertise-card:hover {
      transform: translateY(-5px);
      box-shadow: 0 8px 20px rgba(0, 0, 0, 0.08);
    }

    .timeline-instruction {
      text-align: center;
      font-size: 0.95rem;
      color: #6c757d;
      margin: 0.5rem auto 1.5rem auto;
      font-style: italic;
    }

    @media (max-width: 768px) {
      .intro-grid {
        flex-direction: column;
        align-items: center;
      }

      .timeline {
        padding-left: 1rem;
      }

      .timeline-item::before {
        left: -1rem;
      }

      .timeline-content-header {
        flex-wrap: wrap;
        gap: 0.5rem;
      }

      .timeline-content img {
        width: 20px;
        height: 20px;
      }

      .expertise-grid.static {
        flex-direction: column;
        align-items: center;
      }

      .expertise-card {
        width: 90%;
        padding: 1rem;
        margin-bottom: 1.5rem;
        text-align: center;
      }
    }