title: Customise Firefox extension using chrome/userChrome.css
body: <p>I have foxclocks installed &quot;{d37dc5d0-431d-44e5-8c91-49419370caa1}.xpi&quot;</p>
  <p>I have enabled use of chrome/userChrome.css and have hidden menu items so I know it is working.</p>
  <p>I like to hide the &quot;closer&quot; in fox clocks but how do I reference it in chrome/userChrome.css</p>
  <p>I tried</p>
  <pre><code>#closer { display: none !important } 
  </code></pre>
  <p>but didnt work?</p>
  <p>See image below</p>
  <p><a href="https://i.stack.imgur.com/yPBM8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yPBM8.png" alt="enter image description here" /></a></p>