{# htmx fragment: in-app reading overlay for an investigation, shown as a large
   centered window over a dimmed backdrop (like the image lightbox, sized for
   reading). Returned for HX-Request GETs of /investigation/<id>; swapped into
   #investigation-overlay. Click the backdrop (outside the panel), the ✕, or Esc
   to close — history.back() restores the dashboard snapshot (overlay cleared). #}
<div class="inv-backdrop" onclick="if (event.target === this) closeInvestigation()">
  <div class="inv-overlay" role="dialog" aria-modal="true"
       aria-label="Bug {{ bug_id }} investigation">
    <div class="inv-overlay-bar">
      <button class="inv-overlay-close" type="button"
              onclick="closeInvestigation()" aria-label="Close investigation">✕</button>
      <span class="inv-overlay-title">Bug <strong>{{ bug_id }}</strong> · Investigation</span>
      <a class="investigation-bz"
         href="https://bugzilla.mozilla.org/show_bug.cgi?id={{ bug_id }}"
         target="_blank" rel="noopener">Open in Bugzilla&nbsp;↗</a>
    </div>
    <div class="inv-overlay-scroll">
      <div class="investigation-main">
        {% include "_investigation_content.html" %}
      </div>
    </div>
  </div>
</div>