Settings: hidden Admin entry (opens /admin in the app window); admin page keeps a back link on phones

frontend/admin.html

@@ -287,7 +287,7 @@
     }
     .nav { display: none; }
     @media (max-width: 760px) {
-      .tabs, .top .ghost.desk { display: none; }
+      .tabs, .top .desk-only { display: none; }
       .top { padding: 10px 14px; }
       .nav {
         position: fixed; left: 0; right: 0; bottom: 0; z-index: 50; display: grid; grid-auto-flow: column; grid-auto-columns: 1fr;
@@ -343,7 +343,7 @@
     <a class="brand" href="/admin#editor" data-home style="text-decoration:none;color:inherit"><i><svg viewBox="0 0 24 24"><path d="M9 18V6l10-2v12"/><circle cx="6.5" cy="18" r="2.5"/><circle cx="16.5" cy="16" r="2.5"/></svg></i>Lyrics Studio</a>
     <nav class="tabs" role="tablist" id="tabsTop"></nav>
     <span class="grow"></span>
-    <a class="ghost desk" href="/">← Back to app</a>
+    <a class="ghost back-app" href="/">← <span class="desk-only">Back to </span>App</a>
     <button id="logoutBtn" class="ghost">Sign out</button>
   </header>