Just to make it clear at the start, I'm using the Pale Moon optimised build rather than normal Firefox - however, I don't think that actually makes any difference to this question. As I never use the history dropdown button, the Bookmark button or the Go button in the address bar, I added three lines into userChrome.css to hide them: #star-button { display: none !important; } #urlbar .autocomplete-history-dropmarker { display: none !important; } #go-button-stack { display: none !important; } This works fine and hides all three buttons. However, if the website you're on is Verified (i.e. you get the nice shiny colourful 'Verified by: XXXXXX' details on the left of the URL bar, there ends up being a little gap at the right-hand side of the URL bar that's not present when the website is NOT verified. It implies to me that the Verified bit is a kind of optional sub-component of the main URL bar which leaves space at the end for any buttons, including a default gap between buttons, so when you hide those buttons all that's left is the default gap. Is there anything I can do to stop this gap appearing when I remove these buttons?