{% macro avatar(name, avatar_url=None, initials=None, size='md', class_name='') -%}
  <span class="avatar avatar-{{ size }} {{ class_name }}" aria-label="{{ name }}">
    {% if avatar_url %}
      <img src="{{ avatar_url }}" alt="{{ name }}">
    {% else %}
      <span>{{ initials or (name[:2] if name else '?') }}</span>
    {% endif %}
  </span>
{%- endmacro %}