/*
How To:
1. Find your firefox profile folder : https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data
2. create a "chrome" folder if it doesn't exist
3. Paste content of this gist in a "userChrome.css" file
4. Restart Firefox
Don't hesitate to say if there are bugs, I only tested this for my workflow : I don't use tabs
at all but I want to see the bar if I open a tab by mistake (otherwise I sometimes lose a tab)
*/
#tabbrowser-tabs, #tabbrowser-tabs > .tabbrowser-arrowscrollbox {
	min-height: 0 !important;
}

/* Thanks to @Speravir for making it work again in the latest versions. */
#tabbrowser-tabs tab[first-visible-tab="true"][last-visible-tab="true"] {
	visibility: collapse;
}

/* I don't use tabs so I just hide the new tab button. You should be able to use a similar trick as the rule above with
css siblings selectors if you want to keep it when the tab bar is visible. */
#tabbrowser-tabs .tabs-newtab-button { 
	visibility: collapse !important;
}

#tabbrowser-tabs tab {
	min-height: var(--tab-min-height)
}