Tableiste im Firefox ausblenden.

[Xenos Yifu]

Da ja Addons diesbezüglich nicht mehr funktionieren, hier ein Eintrag für die CSS.
Von mir getestet mit Firefox 101.0.1 (64-Bit) unter Win 11 Pro, klappt bei mir tadellos.

Code:

/*
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. Go to about:config and set toolkit.legacyUserProfileCustomizations.stylesheets to true
5. 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)
*/

/* Copy the default settings for --tab-min-height as --hidetabs-tab-min-height */
:root {
    --hidetabs-tab-min-height: 33px;
}

:root[uidensity=compact] {
    --hidetabs-tab-min-height: 29px;
}

:root[uidensity=touch] {
    --hidetabs-tab-min-height: 41px;
}

/* Set --tab-min-height to 0px so tab bar can disappear */
#tabbrowser-tabs {
    --tab-min-height: 0px;
}

/* Restore minimum height when more than one tab */
#tabbrowser-tabs tab {
    min-height: var(--hidetabs-tab-min-height);
}

/* Collapse tab bar when there is only one tab (tab is both first & last) */
#tabbrowser-tabs tab[first-visible-tab="true"][last-visible-tab="true"] {
    visibility: collapse;
}

/* Hide the New Tab button when there is only one tab (first visible tab is
   adjacent to new tab button) */
#tabbrowser-tabs tab[first-visible-tab="true"] + #tabs-newtab-button {
    visibility: collapse;
}