You can set browser.tabs.tabmanager.enabled = false on the about:config page to hide the "List all tabs" (Tab Manager) button.

You can open the about:config page via the location/address bar. On the warning page, you can click "Accept the Risk and Continue"to open about:config.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Firefox 106+ has a "Firefox View" button at the left end of the Tab bar that you can remove via "Remove from Tab Bar" via the right-click context menu.

• https://support.mozilla.org/en-US/kb/how-set-tab-pickup-firefox-view

Thanks for the quick help! I have set browser.tabs.tabmanager.enabled = false, and indeed the dropdown button at the right has disappeared. But the + button at the left is still there, so the tab bar still does not disappear. It looks like this

tab:only-of-type, tab:only-of-type + #tabs-newtab-button {

  display: none !important;

}

does no longer work with the current Firefox version. Some change or replacement is needed for this code.

Try this code in userChrome.css with the Firefox View button and the the "List all tabs" (Tab Manager) button hidden/removed.

tab[first-visible-tab=true][last-visible-tab=true],
tab[first-visible-tab=true][last-visible-tab=true] + #tabbrowser-arrowscrollbox-periphery{
  display:none!important;
}
#tabbrowser-tabs, #tabbrowser-arrowscrollbox {min-height: 0 !important;}

This works. Thanks a lot!

I had the same problem with FF106 and cor-el's solution worked for me as well. Many thanks.

I have this problem again, having just upgraded to Firefox 110, despite having the code above. Can anyone offer an updated solution please ?

I solved with this code:

#tabbrowser-tabs .tabbrowser-tab:only-of-type,
tab[first-visible-tab=true][last-visible-tab=true],
tab[first-visible-tab=true][last-visible-tab=true] + #tabbrowser-arrowscrollbox-periphery { 
  visibility: collapse !important; }
#tabbrowser-tabs, 
#tabbrowser-arrowscrollbox {
  min-height: 0 !important; }

This code would probably be better as in 110 support for first-visible-tab and last-visible-tab is removed (#1808661).

/* Hide Tab bar with only one Tab - [110] */
#tabbrowser-tabs .tabbrowser-tab:only-of-type,
#tabbrowser-tabs .tabbrowser-tab:only-of-type + #tabbrowser-arrowscrollbox-periphery{
  display:none !important;
}
#tabbrowser-tabs, #tabbrowser-arrowscrollbox {min-height:0!important;}
/* #TabsToolbar:not(:hover) */ #alltabs-button {display:none !important;}

Thanks Iceberg, your solution worked for me.

Iceberg's solution worked for me, thanks.

If both solutions work, what makes one "better"? Shorter? Faster? More durable for the future? Just trying to understand and learn a little.

The cor-el code is better. As first-visible-tab and last-visible-tab were removed from version 110 of Firefox. There is only first-visible-unpinned-tab. I don't know if it is better display: none or visibility:collapse. They seem to work both well.