Hiding backwards and forwards buttons no longer works

I've had the backwards and forwards navigation buttons hidden from the toolbar a long time ago, now wanted to do that again. A different line in the same CSS file works, but not this part, so it's not an issue of the wrong path or so. Did an element name change or so?

This is my current userChrome.css:

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");
#context-navigation, #context-sep-navigation { display:none !important; }
#back-button, #forward-button { display:none !important; }
#nav-bar #back-button, #nav-bar #forward-button { display: none !important; }

* {scroll-snap-type: none !important}

I'm using Firefox 146.0.1.