Don't depend on [inFullscreen] attribute for navigator-toolbox

Just use :root[sizemode="fullscreen"] instead

chrome/autohide_toolbox.css

@@ -20,7 +20,7 @@ See the above repository for updates as well as full license text. */
 }
 
 :root[sizemode="fullscreen"],
-#navigator-toolbox[inFullscreen]{ margin-top: 0 !important; }
+:root[sizemode="fullscreen"] #navigator-toolbox{ margin-top: 0 !important; }
 
 #navigator-toolbox{
   position: fixed !important;

chrome/overlay_fullscreen_toolbars.css

@@ -4,16 +4,16 @@ See the above repository for updates as well as full license text. */
 /* Makes toolbars appear as overlay instead of pushing down the website in fullscreen mode */
 
 @media (-moz-bool-pref: "browser.fullscreen.autohide"){
-  #navigator-toolbox[inFullscreen]{
+  :root[sizemode="fullscreen"] #navigator-toolbox{
     position: fixed !important;
     width: 100vw;
     z-index: 1;
     transition: margin-top 100ms ease-in-out 600ms;
   }
-  #navigator-toolbox[inFullscreen][style=""],
-  #navigator-toolbox[inFullscreen]:hover,
-  #navigator-toolbox[inFullscreen]:focus-within,
-  #mainPopupSet:has(> #appMenu-popup[panelopen="true"]) ~ #navigator-toolbox[inFullscreen]{
+  :root[sizemode="fullscreen"] #navigator-toolbox[style=""],
+  :root[sizemode="fullscreen"] #navigator-toolbox:hover,
+  :root[sizemode="fullscreen"] #navigator-toolbox:focus-within,
+  #mainPopupSet:has(> #appMenu-popup[panelopen="true"]) ~ #navigator-toolbox{
     transition-delay: 0ms;
     margin-top: 0 !important;
   }

chrome/toolbars_below_content.css

@@ -52,8 +52,8 @@ See the above repository for updates as well as full license text. */
   .panel-viewstack{ max-height: unset !important; }
 
   /* Fullscreen mode support */
-  #navigator-toolbox[inFullscreen]{ margin-top: 0 !important }
-  #navigator-toolbox[inFullscreen][style*="margin-top"]{ visibility: collapse }
+  :root[sizemode="fullscreen"] #navigator-toolbox{ margin-top: 0 !important }
+  :root[sizemode="fullscreen"] #navigator-toolbox[style*="margin-top"]{ visibility: collapse }
   #fullscr-toggler{ bottom: 0; top: unset !important; }
   
   /* These three rules exist for compatibility with autohide_toolbox.css */