Menubar tab moves under the brand in accent green; Admin hidden in fullscreen

The menu bar's show/hide tab was centred on the screen, exactly where a
centred tile's own title-bar tab lands once both bars are hidden: two
identical tabs on top of each other, with the tile's unreachable. The tab
now sits at the left under the ProdDash brand and wears the accent colour,
so it never coincides with a tile tab and reads unmistakably as the
dashboard's. To keep it off a top-row tile's status dot and title it
straddles the bar's bottom edge while the bar is shown (mostly on the bar,
a short lip below) and becomes a slim tab at the very top edge when the bar
is hidden.

The Admin link is hidden in fullscreen, including when the menu bar is
brought back there.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RNYUv9EyrGSFmCnmH7WYKH

public/index.html

@@ -42,7 +42,7 @@
       <div class="menu" id="layout-menu" hidden></div>
     </div>
 
-    <a class="tb-btn" href="/admin/" title="Configure modules (server-wide)">
+    <a class="tb-btn" id="admin-link" href="/admin/" title="Configure modules (server-wide)">
       <svg width="13" height="13" viewBox="0 0 24 24" fill="currentColor" aria-hidden="true">
         <path d="M12 15.5a3.5 3.5 0 1 0 0-7 3.5 3.5 0 0 0 0 7Zm8.4-2.1.1-1.4-.1-1.4 1.7-1.3-1.6-2.8-2 .7a7.9 7.9 0 0 0-2.4-1.4l-.3-2.1H11l-.3 2.1a7.9 7.9 0 0 0-2.4 1.4l-2-.7L4.7 9.3 6.4 10.6l-.1 1.4.1 1.4-1.7 1.3 1.6 2.8 2-.7a7.9 7.9 0 0 0 2.4 1.4l.3 2.1h2.8l.3-2.1a7.9 7.9 0 0 0 2.4-1.4l2 .7 1.6-2.8-1.7-1.3Z"/>
       </svg>