Bug report: the antikibitzer's toggle button (which appears at the top right of the browser window's content area) doesn't work correctly for me (on recent Firefox on Windows) because the loop that attempts to identify the antikibitzer stylesheet fails. It fails because an earlier stylesheet in the list (actually, the very first) has a null href.

A simple fix is to change the obvious line in antikibitzer.js to this:

if (document.styleSheets[i].href && document.styleSheets[i].href.indexOf("antikibitzer") > 0)

but I make no guarantee that this is the fix the author of the code would prefer.