// Mobile: the right-rail FAB is stacked ABOVE the tree FAB and opens the right
// rail (TOC + page widgets) in the full-viewport Overlay (overlay.js). It only
// appears when the rail actually has content — runs after toc.js has had a
// chance to populate the rail (script order in page/main.html), so an
// otherwise-empty rail shows no FAB. Hidden on desktop by .fab CSS.
document.addEventListener("DOMContentLoaded", function () {
  var aside = document.querySelector("aside.sidebar");
  if (!aside || !aside.children.length) return;

  var fab = document.createElement("button");
  fab.type = "button";
  fab.className = "btn btn-fab fab fab-rail";
  fab.title = "Contents";
  fab.setAttribute("aria-label", "Contents");
  fab.textContent = "≡";
  fab.addEventListener("click", function () {
    if (typeof openOverlay === "function") openOverlay(aside);
  });
  document.body.appendChild(fab);
});
